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Cytogenetic findings in childhood acute lymphoblastic leukemia
Cytogenetic Findings in Childhood Acute Lymphoblastic Leukemia Jerzy R. Kowalczyk, Mauro Grossi, and Avery A. Sandberg
ABSTRACT: Chromosome studies were performed on the bone marrow cells of 42 children with newly diagnosed acute lymphoblastic leukemia (ALL). All the children were subsequently treated with the same protocol. Chromosomal abnormalities were found in 25 patients, i.e., in 59.5% of the cases. Hyperdiploidy was observed in 21.4%, hypodiploidy in 14.3%, and pseudodiploidy in 23.8% of the children. The most frequent structural aberrations were translocations, which were found in half of the patients with abnormal karyotypes. Chromosomes #5, #6, #7, #9, #14, #17, and #21 were involved in different types of changes most frequently. Because these findings correspond with observations published by others, they can be regarded as evidence of nonrandom involvement of these chromosomes in rearrangements in ALL. Special attention should be also paid to the deletion of 6q, which seems to be relatively common in ALL. In 12 cases, clanal evolution of karyotypic changes was observed. INTRODUCTION There are still limited data on b a n d e d chromosome studies in chidren with acute lymphoblastic leukemia (ALL) [1-5]. The fuzzy and ill defined appearance of the leukemic chromosomes [6] makes b a n d i n g studies in ALL very difficult and, i n some cases, impossible. The proportion of patients with ALL having chromosomal abnormalities in the bone marrow cells is about 50% [2] or more [5]. The small n u m b e r of patients optimally studied and the complexity of the karyotypes make the identification of n o n r a n d o m patterns in ALL very difficult at present. However, the Third International Workshop on Chromosomes in 1980 compiled the results obtained in 17 laboratories. These studies, on 330 patients with ALL, indicate that chromosome examination may be of diagnostic and prognostic value in ALL [5], and they define some subgroups of ALL based on n o n r a n d o m karyotypic changes. In a search for further n o n r a n d o m chromosomal abnormalities in ALL, we studied a group of children with n e w l y diagnosed ALL. These patients were subsequently treated with the same i n d u c t i o n therapy, thus affording an u n u s u a l opportunity to correlate the chromosome findings with the clinical features and the results of therapy.
From the Departmentof Geneticsand Endocrinology(A. A. S., J. R. K.) and the Departmentof Pediatrics (M. G.), RoswellPark MemorialInstitute, Buffalo,NY. Address requests for reprints to Dr. Avery A. Sandberg, Department of Genetics and Endocrinology, Roswell Park Memorial Institute, 666 Elm Street, Buffalo, N Y 14263. Received October 1, 1983; accepted February 8, 1984.
47 © 1985 by Elsevier Science PublishingCo., Inc. 52 VanderbiltAve., New York, NY 10017
Cancer Geneticsand Cytogenetics15, 47-64 (1985) 0165-4608/85/$03.30
48
J.R. Kowalczyk et al.
MATERIALS AND METHODS
A total of 42 c h i l d r e n (23 males and 19 females) diagnosed as having ALL between 1973 and 1979 were studied. No case was i n c l u d e d in the study unless the marrow cells were e x a m i n e d cytogenetically during the initial untreated state of ALL or during relapse of the disease. Short-term cultures (24 hr) without PHA were utilized on bone marrow material to obtain a sufficient n u m b e r of metaphases for chromosome analysis. The initial karyotypic study was performed with conventional Giemsa staining, followed by Qb a n d i n g in each patient. Usually, 25-50 metaphases were counted and e x a m i n e d in the microscope. The b a n d i n g patterns were established from photographs of at least 5 metaphases. The majority of the patients was studied twice or more times during the clinical course of the disease. The Paris nomenclature system was generally used in describing the chromosome abnormalities [7]. RESULTS The age of the 42 c h i l d r e n studied ranged from five months to 17 years; 25 patients died during the time of observation, 12 are still on the treatment protocol, and 5 are off t h e r a p y and in complete remission. Chromosomal abnormalities were found in 25 children, i.e., in 59.5% of cases; 17 c h i l d r e n (40.5%) had normal karyotypes in the bone marrow cells at the time of diagnosis. More than half of the boys had chromosomal abnormalities (60.9%); the percentage in the girls was 57.9%. The presence of two or more clones in the same bone marrow aspirate was shown to exist in 19 cases e x a m i n e d by b a n d i n g techniques. Sixteen of 25 c h i l d r e n with chromosomal changes also had metaphases with normal karyotypes (group AN) in the marrow and 9 had only abnormal cells. The data regarding the presence or absence of chromosomal aberrations in bone marrow are shown in Table 1. Chromosome Number Distribution
Among children with abnormal karyotypes, 9 had h y p e r d i p l o i d y , 6 had h y p o d i p l o i dy, and 10 presented with p s e u d o d i p l o i d y . The data are s u m m a r i z e d in Table 2. As can be seen, most of the c h i l d r e n with abnormal karyotypes s h o w e d h y p e r d i p loidy of more than 50 c h r o m o s o m e s (19%) and p s e u d o d i p l o i d y , i.e., normal chromosome n u m b e r but with abnormal karyotypes (23.8%). The various types of aneup l o i d y were distributed almost equally between both sexes.
Table 1
Presence of normal and abnormal karyotypes in 42 children with ALL
Group
M
F
Total
Percent
N NA AA
9 7 7
8 9 2
17 16 9
40.5 38.1 21.4
M, male; F, female; N, only normal karyotypes; NA, normal and abnormal karyotypes; AA, only abnormal karyotypes.
49
Cytogenetic Findings in Childhood ALL
Table 2
Children with ALL d iv id e d according to modal c h r o m o s o m e numbers.
Group
M
F
Total
Percent
Hyperdiploidy 47-50 Hyperdiploidy ~50 Hypodiploidy Pseudodiploidy Normal
1 4 3 6 9
-4 3 4 8
1 8 6 10 17
2.4 19.0 14.3 23.8 40.5
Chromosomal Rearrangements Translocations were present in 13 children (6 boys and 7 girls), i.e., in 31% of all patients studied or in 52% of children with abnormal karyotypes. Deletions were found in 10 cases (7 males and 3 females, 23.8%) and marker c h r o m o s o m e s of unk n o wn origin in 3 patients (7.1%). Details of the ch r o m o so m al abnormalities in these children are presented in Table 3. The karyotypic abnormalities in the 25 cases are described below in detail.
Figure I Karyotype of bone marrow cell of patient A.M., consisting of 46,X, 14q + (arrow), - 16, + 21, + mar.
50
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Cytogenetic F i n d i n g s in C h i l d h o o d ALL
51
Patient 1 (A. M.). A. M. was k n o w n to have Down's syndrome. The initial analysis with b a n d i n g techniques revealed the presence of 4 clones (Fig. 1). The basic one was 4 6 , X , - X , 1 4 q + , - 1 6 , + 21, + m a r , w h i c h was observed in 7 metaphases karyotyped. There were also 6 metaphases with the karyotype 47,XX,14q + , + mar, 5 cells with 4 4 , X X , 1 4 q + , - 1 6 , - 1 9 , and 3 metaphases with 4 5 , X , - X , 1 4 q + , - 1 6 , + 2 1 . Only abnormal cells were observed in the marrow in the initial study; in all cells, an abnormal c h r o m o s o m e #14 was observed. It was formed by a translocation of c h r o m o s o m a l segments of u n k n o w n origin to its distal part of the long arm. Most of the cells analyzed also lacked a c h r o m o s o m e #16. However, an extra chromosome #21, characteristic for Down's syndrome, was not present in all the cells examined. Cytogenetic studies of bone marrow cells obtained during remission constantly showed trisomy 21 as the only anomaly. Patient 2 (B. M.). The marrow cells showed a m o d e of 55 c h r o m o s o m e s with a considerable scatter from 53 to 58. Q-banding, though of poor quality, revealed the extra c h r o m o s o m e s to be #6, #7, #9, #10, #13, #14, and two of #21 and #22. No normal karyotypes were found in the initial study.
Figure 2 Hyperdiploid karyotype of patient G. G. (case 3) with a 7 p - and an isochromosome of 17q (arrows).
52
J.R. Kowalczyk et al. Patient 3 (G. G.). The modal karyotype was 56,XX, + 6, + 7, + 9, + 10, + 17, + 17,iso/ 17q/, + 21, + 21, + m a r l , + mar2 (Fig. 2). However, there were also clones with 55-56 chromosomes that had additional chromosomal rearrangements, e.g., 6 q - (q21) and 7 p - ( p 1 1 ) , as well as other marker chromosomes. About 50% of the bone marrow cells showed a normal karyotype: 46,XX.
Patient 4 (H. W.). The initial chromosome study showed a mode of 47 chromosome. Q-banding revealed the karyotype to be 4 7 , X Y , 1 7 q + , + 2 1 (Fig. 3). Some metaphases with a normal karyotype (46,XY) were also present in the specimen.
Patient 5 (S. R.). The modal chromosome n u m b e r was 46. However, in almost all cells, p s e u d o d i p l o i d y was observed, with missing chromosomes in groups A and D and extra chromosomes in groups C and G. Q-banding was of poor quality, but in all probability, the karyotype was 46,XY, - 3, + 7, - 15, + 21. Patient 6 (S. E.). The marrow cells showed a normal karyotype: 46,XX. However, there was a substantial n u m b e r of abnormal cells (9 of 27) with the karyotype 45,XX, - 5.
Figure 3
Bone marrow cell with the karyotype 47,XY,17q + (arrow),+ 21 (case 4).
Cytogenetic Findings in C h i l d h o o d ALL
53
Patient 7 (C. P.). The m o d a l karyotype was 4 5 , X X , - C ; Q-banding revealed that the missing c h r o m o s o m e was a #9. This a n o m a l y was present in all cells karyotyped.
Patient 8 (D. H.). Direct marrow preparations s h o w e d a m o d e of 53 chromosomes, with a considerable scatter from 46 to 54. Four b a n d e d metaphases showed the cytogenetic course of evolution. In one cell, an i s o c h r o m o s o m e of the long arm of # 7 and extra c h r o m o s o m e s #8, #13, and #21 were found. Two cells had additional chromosomes #2, #5, #21, and #22. One cell had an abnormal c h r o m o s o m e 1 7 q + , in a d d i t i o n to the two normal #17 chromosomes. This case was described previously [2]. Patient 9 (S. T.). All bone marrow cells had an abnormal karyotype with 45 chromosomes. The metaphases were missing one c h r o m o s o m e # 5 and contained a translocation between the long arms of chromosomes # 3 and #18 (Fig. 4). In addition, a deletion of the long arm of # 1 6 was seen. Patient 10 (G. D.). The chromosomal study revealed two abnormal cell clones in the bone marrow. One clone showed a male karyotype with 54 chromosomes. The extra c h r o m o s o m e s were #3, #6, #10, #13, #14, #16, and two #21s. The other clone w i t h 55 c h r o m o s o m e s had, in addition, an extra X chromosome. No structurally abnormal c h r o m o s o m e s were observed. Figure 4 Karyotype of case 9 with the following anomalies (arrows): Translocation t(3q;18q), deletion of the long arm of chromosome #16, and a missing #5.
J.R. Kowalczyk et al.
54
Patient 11 (I. M.). The m o d a l c h r o m o s o m e number was 46, with a normal karyotype. However, there was a substantial n u m b e r of abnormal cells having 45 chromosomes with a missing chromosome in group C. Banding analysis revealed a marker c h r o m o s o m e due to translocation between c h r o m o s o m e s # 3 and #7. Patient 12 (L. W.). The marrow cells obtained at the time of diagnosis s h o w e d a normal karyotype: 46,XY. The patient relapsed 11 months later, and at that time, cytogenetic examination revealed the presence of an additional segment on the long arm of chromosome #21. This a n o m a l y was the result of a translocation b e t w e e n the short arm of c h r o m o s o m e # 9 (breakpoint at p13) and the long arm of chromosome #21 (breakpoint at q13) (Fig. 5), Patient 13 (M. C.). The m o d a l c h r o m o m s o m e n u m b e r was 46, but b a n d i n g revealed an abnormal karyotype with deletion of the short arm of c h r o m o s o m e #1 (breakpoint at p32) and translocation of this segment to the short arm of c h r o m o s o m e #12 (breakpoint) at p12) (Fig. 6). Patient 14 (M. W.). The bone marrow s p e c i m e n from this patient was of very poor quality. The cytogenetic examination revealed cells with 52 chromosomes, as well as normal ones with the karyotype 46,XY. Banding analysis to determine the exact
Figure 5
Karyotype of case 12 with a translocation, t(9p;21q), in relapsed bone marrow.
Cytogenetic Findings in Childhood ALL
Figure 6
55
Karyotype of case 13: 46,XX,t(1;12)(p32;p12) (arrows).
origin of the extra chromosomes was unsuccessful. Despite this, we decided to include this patient in the study, particularly for analysis of the clinical significance of chromosomal abnormalities in ALL. Patient 15 (M. J.). The initial chromosome study showed a normal karyotype, 46,XY, in the bone marrow cells. After 4.5 years, a follow-up study showed about 50% of the metaphases to have an abnormal karyotype, with chromosome #19 missing. The patient had gone through several central nervous system relapses, but was still in bone marrow remission. Patient 16 (P. M.). A bone marrow obtained at the time of diagnosis was shown to have polyploid cells containing 55 chromosomes in addition to chromosomally normal cells. The cells with 55 chromosomes had extra chromosomes #2, #4, #9, #14, #15, #19, #20, and two #21s. Patient 17 (P. J.). The modal chromosome number was 46. Banding analysis showed an interstitial deletion of the long arm of chromosome #5. Two and onehalf years later, the patient relapsed, and karyotypic evolution of the previous anomaly could be observed in cells with 45 chromosomes, where chromosome #5 was missing.
56
J.R. Kowalczyk et al.
Patient 18 (B. R.). The marrow contained cells with a m o d e of 46 chromosomes. However, b a n d i n g analysis showed one # 7 c h r o m o s o m e with an extra segment on its long arm. The extra segment seemed to be originated from the long arm of chrom o s o m e #1 (Fig. 7). Patient 19 (B. D.). The m o d a l c h r o m o s o m e n u m b e r in the first study was 46, with a normal karyotype. At the time of the third relapse, clonal abnormalities were observed in a d d i t i o n to k a r y o t y p i c a l l y normal cells. Banding revealed the abnormal metaphases to be p s e u d o d i p l o i d and to contain an interstitial deletion of the long arm on chromosome #5, a missing chromosome #20, and an extra marker chromosome, w h i c h was an i s o c h r o m o s o m e of the long arm of #17 (Fig. 8). Patient 20 (B. K.). A bone marrow s p e c i m e n was shown to contain a mixture of cells with about half of the ceils having a normal d i p l o i d karyotype and the other half being p s e u d o d i p l o i d due to loss of a chromosome # 5 and an extra chromosome #17.
Figure 7 (case 18).
Trisomic part of the long arm of #1 (arrow) translocated to the long arm of #7
Cytogenetic Findings i n Childhood ALL
57
Figure 8 Pseudadiploid karyotype of case 19 showing an interstitial deletion of chromosome #5 (5q-) and an isochromosome for 17q, i(17q) (arrows).
Patient 21 (B. T.). In this patient, clonal evolution of cytogenetic abnormalities was seen during the course of the disease. The first examination showed a normal karyotype, 46,XX, in the bone marrow cells. After the patient relapased 17 months later, in addition to normal metaphases, abnormal ones were observed, with one X chromosome missing and a modal chromosome n u m b e r of 45. Cytogenetic study during the second relapse showed an additional abnormality resulting from deletion of the short arm of a chromosome #17 (breakpoint at p11). One m o n t h later, additional abnormalities were found, i.e., an extra chromosome #20, missing #21 and #22, and a marker chromosome originating from a translocation between the long arms of chromosomes #21 and #22 (Fig. 9).
Patient 22 (B. W.). The marrow cells contained a mode of 46 chromosomes. All cells studied with b a n d i n g had a deletion of the long arm of a chromosome # 6 at breakpoint q23. A few metaphases having 47 chromosomes were observed, due to an extra chromosome # 8 in addition to the deleted #6.
Patient 23 (F. R.). The modal chromosome n u m b e r was 51. The extra chromosomes were #4, #9, #16, #17, and two #21s and an u n k n o w n marker chromosome;
58
J.R. Kowalczyk et al.
Figure 9 Karyotype of bone marrow cell from patient B.T. (case 21) in second relapse: 45,X,del(17)(p11), + 20,t(21q;22q) (arrows).
chromosomes # 7 and #12 were missing. In addition, a deletion of the long arm of chromosome #1 was observed (breakpoint q41), with the deleted segment being translocated to the long arm of the other chromosome #1 (breakpoint q25). Most cells k a r y o t y p e d also had a deletion of the short arm of a c h r o m o s o m e # 9 (Fig. i0). P a t i e n t 24 (H. K.). This case has been reported in detail in a previous paper [8].
The first chromosomal study of the bone marrow showed that the m o d a l chromosome n u m b e r was 54, but that there was a substantial number of cells with 27 chromosomes, as well as normal cells. The cells with 27 chromosomes had only one c h r o m o s o m e in each pair, except for pairs #10, #14, #18, and #21. The # 7 chromosome was structurally changed, with additional segments from an u n k n o w n chromosome having been translocated to the distal end of its short arm. Therefore, normal chromosomes # 7 were not observed. The cells with 54 c h r o m o s o m e s contained an exact d u p l i c a t i o n of the set found in the cells with 27 chromosomes. Six months later, w h e n the patient was in relapse following complete remission, a bimodal c h r o m o s o m e n u m b e r of 27 and 46 was found in bone marrow. All of the cells with 27 chromosomes had a normal # 7 chromosome. In two cells with 54 chromosomes, w h i c h contained exact d u p l i c a t i o n of the cells with 27 c h r o m o s o m e s from the same specimen, both # 7 s chromosomes were normal.
Cytogenetic Findings in Childhood ALL
59
Figure 10 Hyperdiploid karyotype of case 23: 51,XY,t(1;1)(q41;q25),+4,del(6)(q21),-7,+9, de19(p13),- 12, + 16, + 17, + 21, + 21, + mar.
Patient 25 (H. D.). A bone marrow s p e c i m e n had been shown to have a m o d e of 46 chromosomes. Detailed analysis of b a n d e d karyotypes revealed an abnormal chromosome #6, due to deletion of the long arm at the breakpoint q21, and an abnormal #9, due to deletion of the short arm (breakpoint p11) (Fig. 11).
Karyotypic Evolution In four children, the first cytogenetic examinations revealed normal karyotypes in the bone marrow, however, chromosomal abnormalities of a clonal nature were observed in relapse. In an additional eight children, clanal evolution of previous abnormalities could also be observed during the course of disease, These data are presented in Table 4.
DISCUSSION In the present study, clonal abnormalities in bone marrow cells were identified in 59.5% of c h i l d r e n with ALL. This percentage is slightly higher than that observed by Oshimura et al. [2], Cimino et al. [1], and S w a n s b u r y et al. [4] and is slightly
60
J.R. Kowalczyk et al.
Figure 11 Karyotype of case 25 showing deletions of the long arm of chromosome #6 and of the short arm of #9. lower than that reported by Williams et al. [9]. However, it is in good agreement with a more extensive survey of the Third International Workshop on Chromosomes in Acute Leukemia, where 62% of the children with ALL showed chromosomal abnormalities [5]. One can expect that, with improvements of banding techniques and other cytogenetic methods for chromosomal analysis of leukemic cells, the percentage of ALL patients with chromosomal aberrations in the initial bone marrow cells may be higher [10]. Generally, it is thought that hypodiploidy is rather rare in ALL [2, 4, 5]. The present study revealed 6 patients (14.3%) with a modal chromosome number less than 46. Recently, Arthur et al. [11] have also found a significant number of hypodiploid clones among their patients with ALL. In 23.8% of our patients, we observed pseudodiploidy. A somewhat higher figure was seen by other authors, from 29.9% to 33% [5, 11, 12]. This fact emphasizes the necessity of chromosome banding examination in all leukemic patients, even if a normal number of chromosomes is found with standard Giemsa staining. Differences exist between laboratories regarding the frequency of structural chromosomal changes in ALL. Two previous papers stated that 12% and 22.9% of patients with ALL had structural abnormalities [5, 13]. In our study, 38% of children had structural rearrangements, and the most frequent were translocations in 13 children, i.e., in more than a half of the patients with chromosomal aberrations. Almost all chromosomes were involved in changes except for chromosome #11
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J . R . K o w a l c z y k et al.
and the Y. Table 5 p r e s e n t s the d i s t r i b u t i o n of aberrations a m o n g the c h r o m o s o m e groups. C h r o m o s o m e # 2 1 was i n v o l v e d m o s t frequently. Different t y p e s of rearr a n g e m e n t s of this c h r o m o s o m e w e r e o b s e r v e d in a l m o s t half of ALL c h i l d r e n w i t h c h r o m o s o m a l aberrations. C h r o m o s o m e s # 7 , # 9 , a n d # 1 7 w e r e i n v o l v e d in a l m o s t o n e - t h i r d of p a t i e n t s a n d c h r o m o s o m e s # 5 , # 6 , and # 1 4 in about 25% of the children. T h e s e findings are in partial a g r e e m e n t w i t h p r e v i o u s reports of O s h i m u r a et al. [2], w h o f o u n d c o m m o n i n v o l v e m e n t of # 2 1 and #6. In the s u r v e y by M i t e l m a n and L e v a n [14], c h r o m o s o m e s # 6 , # 7 , # 1 4 , # 1 7 , and # 2 1 w e r e m o s t f r e q u e n t l y i n v o l v e d , and in the r e p o r t of A r t h u r et al. [11], c h r o m o s o m e s # 6 , # 9 , # 1 4 , and # 2 1 w e r e the m o s t frequent. T h e s e data afford s o m e e v i d e n c e r e g a r d i n g the p o s s i b l e n o n r a n d o m d i s t r i b u t i o n of c h r o m o s o m a l abn o r m a l i t i e s in ALL. It s e e m s that c h r o m o s o m e s # 6 , # 7 , # 9 , # 1 4 , # 1 7 , a n d # 2 1 in ALL-affected b o n e m a r r o w cells are n o n r a n d o m l y i n v o l v e d in r e a r r a n g e m e n t s d u r i n g the c o u r s e of disease. It s h o u l d also be p o i n t e d out that s o m e specific chrom o s o m a l c h a n g e s are r e l a t i v e l y c o m m o n in ALL. P r e v i o u s reports p r e s e n t e d the f r e q u e n t o c c u r r e n c e of a d e l e t i o n of the l o n g arm of a c h r o m o s o m e # 6 [2, 11, 14]. In the p r e s e n t study, w e h a v e f o u n d 4 p a t i e n t s w i t h this aberration, t h o u g h the b r e a k p o i n t s w e r e not the same. It is w o r t h n o t i n g that, in our study, 3 of 4 p a t i e n t s w i t h 6 q - w e r e male. A r t h u r et al. [11] h a v e also f o u n d p r e d o m i n a n t l y m a l e s (5 of 6) w i t h this a b n o r m a l i t y .
Table 5
I n v o l v e m e n t of c h r o m o s o m e groups in p a t i e n t s w i t h ALL w h o h a v e c h r o m o s o m e abnormalities Chromosome number
Patient (1) (2) (3) (4)
1
2
3
4
5
A.M. B.M. G.G. H.W,
(5) S.R.
6
7
+ +
+ +
+
8
10 11 12 13 14 15 16 17 18 19 20 21 22 X Y
+ +
+ +
+
+ +
+
+ + + +
+ +
+
[6) S.E.
+
+ +
+
+
(7) c.P.
+
(8)
D.H. (9) S.T.
(10) G.D. (11) I.T. (12) L.W. (13) M.C. (14) M.W. (15) M.J. (16) P.M. (17) P.J. (18) B.R. (19) B.D, (20) B.K. (21) B.T, (22) B.W. (23] F.R, (24) H.K. (25) H.D. Total
9
+
+ +
+
+ +
+
+
+
+ +
+
+
+
+
+
+
+
+
+
+ +
+
+
+
+
+
+
+
+ +
+
+
+
+ +
+ + +
+
3
+ +
+
2
4
2
+ + +
6
+ 6
+ +
+
+
+
12 3
3
+ + + 8
+
+
+
+ 2
+ 7
4
+
+ 0
2
3
5
+ +
+ 2
4
6
2
2
3
Cytogenetic Findings in C h i l d h o o d ALL
63
Evolution of the karyotype occurred in 12 of the 25 patients with aneuploidy. In some cases, two or more clones were already present at the initial study; in other patients, only one clone was shown to exist at the time of diagnosis. All these patients had normal karyotypes in bone marrow cells during remission. After the patients relapsed, clones with previously observed abnormalities were generally found again, but w i t h some additional rearrangements. These findings seemed to represent cytogenetically more a d v a n c e d changes. Contrary to previous data [2], our material does not s h o w a t e n d e n c y to increased c h r o m o s o m e numbers during karyotypic evolution. Rather, we observed structural rearrangements to be the more frequent a d d i t i o n a l changes. So far, we have failed to find specific chromosomes involved in the genesis of these karyotypic changes [1, 2, 15, 16]. However, we w o u l d like to m e n t i o n two examples of karyotypic evolution in our material. A n interesting case is patient 7, who had a karyotype with a 5 q - as the p r i m a r y change and then, during the progress of disease, the cells were missing a c h r o m o s o m e # 5 c o m p l e t e l y (Table 4). Generally, in contrast to the rather c o m m o n evolution of - 7 from 7 q - , the loss of a c h r o m o s o m e #5 subsequent to the appearance of 5 q - is rather rare. It will be interesting to ascertain whether the same situation will develop in the following examinations in patient 8, w h o presently has a 5 q - chromosome. There were two other cases with a missing # 5 chromosome: at the time of diagnosis in one patient and during relapse in the other. However, we failed to find a 5 q - c h r o m o s o m e in the cells of the same bone marrow s p e c i m e n in both cases. Another interesting karyotypic evolution occurred in two cases (patients 2 and 11 of Table 4) with the above-mentioned deletion of 6q. In these cases, the a n o m a l y a p p e a r e d during the evolution of the karyotype as an a d d i t i o n a l aberration. The group of c h i l d r e n with ALL presented in this article is of special interest in correlating the various c h r o m o s o m e abnormalities with their clinical significance, as all the patients were p l a c e d on the same treatment protocol. In the second article in this series, we will present results of a correlation of findings with the clinical course, survival, and laboratory data of these patients. Supported in part by Public Health Service International Research Fellowship F05 TWO300901 to J.R.K.
REFERENCES 1. Cimino MC, Rowley JD, Kinnealey A, Variakojis D, Golomb HM (1979): Banding studies of chromosomal abnormalities in patients with acute lymphocytic leukemia. Cancer Res 39:227-238. 2. Oshimura M, Freeman AI, Sandberg AA (1977): Chromosomes and causation of human cancer and leukemia. XXVI. Banding studies in acute lymphoblastic leukemia (ALL). Cancer 40:1161-1172. 3. Rowley JD (1980): Chromosome abnormalities in acute lymphoblastic leukemia. Cancer Genet Cytogenet 1:263-271. 4. Swansbury GJ, Secker-Walker LM, Lawler SD, Hardisty RM, Sallen SE, Garson OM, Sakurai M (1981): Chromosomal findings in acute lymphoblastic leukaemia of childhood: An independent prognostic factor. Lancet 2:249-250. 5. Third International Workshop on Chromosomes in Acute Leukemia (1981): Clinical significance of chromosomal abnormalities in acute lymphoblastic leukemia. Cancer Genet Cytogenet 4:95-142. 6. Sandberg AA (1980): The Chromosomes in Human Cancer and Leukemia, Elsevier/North Holland, New York. 7. Paris Conference (1971): Standardization in human cytogenetics. Birth Defects 8:00.
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8. Oshimura M, Freeman AI, Sandberg AA (1977): Chromosomes and causation of human cancer and leukemia. XXIII. Near-haploidy in acute leukemia. Cancer 40:1143-1148. 9. Williams DL, Tsiatis A, Brodeur GM, Look AT, Melvin SL, Bowman WP, Kalwiusky DK, Rivera G, Dahl GV (1982): Prognostic importance of chromosome number in 136 untreated children with acute lymphoblastic leukemia. Blood 60:864. 10. Yunis JJ, Bloomfield CD, Ensrud K (1981): All patients with acute nonlymphocytic leukemia may have a chromosomal defect. N Engl J Med 305:135-139. 11. Arthur DC, Bloomfield CD, Lindquist LL, Peterson BA, Nesbit ME (1981): Chromosome abnormalities in acute lymphoblastic leukemia (ALL): Frequency and clincial implications. Proc AACR 3:345. 12. Kaneko Y, Rowley JD (1981): Correlation of karyotype with prognosis in acute lymphocytic leukemia (ALL). Proc AACR 3:338. 13. Brodeur GM, Williams DL, Bowman WP, Look AT, Kalwinsky DK, Aur RJA, Rivera G, Dahl GV (1981): Cytogenetic features of acute lymphoblastic leukemia (ALL) in children. Proc AACR 3:45. 14. Mitelman F, Levan G (1978): Clustering of aberrations to specific chromosomes in human neoplasms. Hereditas 89:207-232. 15. Whang-Peng J, Knutsen T, Ziegler J, Leventhal B (1976): Cytogenetic studies in acute lymphocytic leukemia- Special emphasis on long-term survival. Med Pediatr Oncol 2:333351. 16. Zuelzer WW, Inoue S, Thompson, RE, Ottenbreit M (1976): Long-term cyt0genetic studies in acute leukemia of children; the nature of relapse. Am J Hematol 1:143-190.
ABSTRACT: Chromosome studies were performed on the bone marrow cells of 42 children with newly diagnosed acute lymphoblastic leukemia (ALL). All the children were subsequently treated with the same protocol. Chromosomal abnormalities were found in 25 patients, i.e., in 59.5% of the cases. Hyperdiploidy was observed in 21.4%, hypodiploidy in 14.3%, and pseudodiploidy in 23.8% of the children. The most frequent structural aberrations were translocations, which were found in half of the patients with abnormal karyotypes. Chromosomes #5, #6, #7, #9, #14, #17, and #21 were involved in different types of changes most frequently. Because these findings correspond with observations published by others, they can be regarded as evidence of nonrandom involvement of these chromosomes in rearrangements in ALL. Special attention should be also paid to the deletion of 6q, which seems to be relatively common in ALL. In 12 cases, clanal evolution of karyotypic changes was observed. INTRODUCTION There are still limited data on b a n d e d chromosome studies in chidren with acute lymphoblastic leukemia (ALL) [1-5]. The fuzzy and ill defined appearance of the leukemic chromosomes [6] makes b a n d i n g studies in ALL very difficult and, i n some cases, impossible. The proportion of patients with ALL having chromosomal abnormalities in the bone marrow cells is about 50% [2] or more [5]. The small n u m b e r of patients optimally studied and the complexity of the karyotypes make the identification of n o n r a n d o m patterns in ALL very difficult at present. However, the Third International Workshop on Chromosomes in 1980 compiled the results obtained in 17 laboratories. These studies, on 330 patients with ALL, indicate that chromosome examination may be of diagnostic and prognostic value in ALL [5], and they define some subgroups of ALL based on n o n r a n d o m karyotypic changes. In a search for further n o n r a n d o m chromosomal abnormalities in ALL, we studied a group of children with n e w l y diagnosed ALL. These patients were subsequently treated with the same i n d u c t i o n therapy, thus affording an u n u s u a l opportunity to correlate the chromosome findings with the clinical features and the results of therapy.
From the Departmentof Geneticsand Endocrinology(A. A. S., J. R. K.) and the Departmentof Pediatrics (M. G.), RoswellPark MemorialInstitute, Buffalo,NY. Address requests for reprints to Dr. Avery A. Sandberg, Department of Genetics and Endocrinology, Roswell Park Memorial Institute, 666 Elm Street, Buffalo, N Y 14263. Received October 1, 1983; accepted February 8, 1984.
47 © 1985 by Elsevier Science PublishingCo., Inc. 52 VanderbiltAve., New York, NY 10017
Cancer Geneticsand Cytogenetics15, 47-64 (1985) 0165-4608/85/$03.30
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J.R. Kowalczyk et al.
MATERIALS AND METHODS
A total of 42 c h i l d r e n (23 males and 19 females) diagnosed as having ALL between 1973 and 1979 were studied. No case was i n c l u d e d in the study unless the marrow cells were e x a m i n e d cytogenetically during the initial untreated state of ALL or during relapse of the disease. Short-term cultures (24 hr) without PHA were utilized on bone marrow material to obtain a sufficient n u m b e r of metaphases for chromosome analysis. The initial karyotypic study was performed with conventional Giemsa staining, followed by Qb a n d i n g in each patient. Usually, 25-50 metaphases were counted and e x a m i n e d in the microscope. The b a n d i n g patterns were established from photographs of at least 5 metaphases. The majority of the patients was studied twice or more times during the clinical course of the disease. The Paris nomenclature system was generally used in describing the chromosome abnormalities [7]. RESULTS The age of the 42 c h i l d r e n studied ranged from five months to 17 years; 25 patients died during the time of observation, 12 are still on the treatment protocol, and 5 are off t h e r a p y and in complete remission. Chromosomal abnormalities were found in 25 children, i.e., in 59.5% of cases; 17 c h i l d r e n (40.5%) had normal karyotypes in the bone marrow cells at the time of diagnosis. More than half of the boys had chromosomal abnormalities (60.9%); the percentage in the girls was 57.9%. The presence of two or more clones in the same bone marrow aspirate was shown to exist in 19 cases e x a m i n e d by b a n d i n g techniques. Sixteen of 25 c h i l d r e n with chromosomal changes also had metaphases with normal karyotypes (group AN) in the marrow and 9 had only abnormal cells. The data regarding the presence or absence of chromosomal aberrations in bone marrow are shown in Table 1. Chromosome Number Distribution
Among children with abnormal karyotypes, 9 had h y p e r d i p l o i d y , 6 had h y p o d i p l o i dy, and 10 presented with p s e u d o d i p l o i d y . The data are s u m m a r i z e d in Table 2. As can be seen, most of the c h i l d r e n with abnormal karyotypes s h o w e d h y p e r d i p loidy of more than 50 c h r o m o s o m e s (19%) and p s e u d o d i p l o i d y , i.e., normal chromosome n u m b e r but with abnormal karyotypes (23.8%). The various types of aneup l o i d y were distributed almost equally between both sexes.
Table 1
Presence of normal and abnormal karyotypes in 42 children with ALL
Group
M
F
Total
Percent
N NA AA
9 7 7
8 9 2
17 16 9
40.5 38.1 21.4
M, male; F, female; N, only normal karyotypes; NA, normal and abnormal karyotypes; AA, only abnormal karyotypes.
49
Cytogenetic Findings in Childhood ALL
Table 2
Children with ALL d iv id e d according to modal c h r o m o s o m e numbers.
Group
M
F
Total
Percent
Hyperdiploidy 47-50 Hyperdiploidy ~50 Hypodiploidy Pseudodiploidy Normal
1 4 3 6 9
-4 3 4 8
1 8 6 10 17
2.4 19.0 14.3 23.8 40.5
Chromosomal Rearrangements Translocations were present in 13 children (6 boys and 7 girls), i.e., in 31% of all patients studied or in 52% of children with abnormal karyotypes. Deletions were found in 10 cases (7 males and 3 females, 23.8%) and marker c h r o m o s o m e s of unk n o wn origin in 3 patients (7.1%). Details of the ch r o m o so m al abnormalities in these children are presented in Table 3. The karyotypic abnormalities in the 25 cases are described below in detail.
Figure I Karyotype of bone marrow cell of patient A.M., consisting of 46,X, 14q + (arrow), - 16, + 21, + mar.
50
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Cytogenetic F i n d i n g s in C h i l d h o o d ALL
51
Patient 1 (A. M.). A. M. was k n o w n to have Down's syndrome. The initial analysis with b a n d i n g techniques revealed the presence of 4 clones (Fig. 1). The basic one was 4 6 , X , - X , 1 4 q + , - 1 6 , + 21, + m a r , w h i c h was observed in 7 metaphases karyotyped. There were also 6 metaphases with the karyotype 47,XX,14q + , + mar, 5 cells with 4 4 , X X , 1 4 q + , - 1 6 , - 1 9 , and 3 metaphases with 4 5 , X , - X , 1 4 q + , - 1 6 , + 2 1 . Only abnormal cells were observed in the marrow in the initial study; in all cells, an abnormal c h r o m o s o m e #14 was observed. It was formed by a translocation of c h r o m o s o m a l segments of u n k n o w n origin to its distal part of the long arm. Most of the cells analyzed also lacked a c h r o m o s o m e #16. However, an extra chromosome #21, characteristic for Down's syndrome, was not present in all the cells examined. Cytogenetic studies of bone marrow cells obtained during remission constantly showed trisomy 21 as the only anomaly. Patient 2 (B. M.). The marrow cells showed a m o d e of 55 c h r o m o s o m e s with a considerable scatter from 53 to 58. Q-banding, though of poor quality, revealed the extra c h r o m o s o m e s to be #6, #7, #9, #10, #13, #14, and two of #21 and #22. No normal karyotypes were found in the initial study.
Figure 2 Hyperdiploid karyotype of patient G. G. (case 3) with a 7 p - and an isochromosome of 17q (arrows).
52
J.R. Kowalczyk et al. Patient 3 (G. G.). The modal karyotype was 56,XX, + 6, + 7, + 9, + 10, + 17, + 17,iso/ 17q/, + 21, + 21, + m a r l , + mar2 (Fig. 2). However, there were also clones with 55-56 chromosomes that had additional chromosomal rearrangements, e.g., 6 q - (q21) and 7 p - ( p 1 1 ) , as well as other marker chromosomes. About 50% of the bone marrow cells showed a normal karyotype: 46,XX.
Patient 4 (H. W.). The initial chromosome study showed a mode of 47 chromosome. Q-banding revealed the karyotype to be 4 7 , X Y , 1 7 q + , + 2 1 (Fig. 3). Some metaphases with a normal karyotype (46,XY) were also present in the specimen.
Patient 5 (S. R.). The modal chromosome n u m b e r was 46. However, in almost all cells, p s e u d o d i p l o i d y was observed, with missing chromosomes in groups A and D and extra chromosomes in groups C and G. Q-banding was of poor quality, but in all probability, the karyotype was 46,XY, - 3, + 7, - 15, + 21. Patient 6 (S. E.). The marrow cells showed a normal karyotype: 46,XX. However, there was a substantial n u m b e r of abnormal cells (9 of 27) with the karyotype 45,XX, - 5.
Figure 3
Bone marrow cell with the karyotype 47,XY,17q + (arrow),+ 21 (case 4).
Cytogenetic Findings in C h i l d h o o d ALL
53
Patient 7 (C. P.). The m o d a l karyotype was 4 5 , X X , - C ; Q-banding revealed that the missing c h r o m o s o m e was a #9. This a n o m a l y was present in all cells karyotyped.
Patient 8 (D. H.). Direct marrow preparations s h o w e d a m o d e of 53 chromosomes, with a considerable scatter from 46 to 54. Four b a n d e d metaphases showed the cytogenetic course of evolution. In one cell, an i s o c h r o m o s o m e of the long arm of # 7 and extra c h r o m o s o m e s #8, #13, and #21 were found. Two cells had additional chromosomes #2, #5, #21, and #22. One cell had an abnormal c h r o m o s o m e 1 7 q + , in a d d i t i o n to the two normal #17 chromosomes. This case was described previously [2]. Patient 9 (S. T.). All bone marrow cells had an abnormal karyotype with 45 chromosomes. The metaphases were missing one c h r o m o s o m e # 5 and contained a translocation between the long arms of chromosomes # 3 and #18 (Fig. 4). In addition, a deletion of the long arm of # 1 6 was seen. Patient 10 (G. D.). The chromosomal study revealed two abnormal cell clones in the bone marrow. One clone showed a male karyotype with 54 chromosomes. The extra c h r o m o s o m e s were #3, #6, #10, #13, #14, #16, and two #21s. The other clone w i t h 55 c h r o m o s o m e s had, in addition, an extra X chromosome. No structurally abnormal c h r o m o s o m e s were observed. Figure 4 Karyotype of case 9 with the following anomalies (arrows): Translocation t(3q;18q), deletion of the long arm of chromosome #16, and a missing #5.
J.R. Kowalczyk et al.
54
Patient 11 (I. M.). The m o d a l c h r o m o s o m e number was 46, with a normal karyotype. However, there was a substantial n u m b e r of abnormal cells having 45 chromosomes with a missing chromosome in group C. Banding analysis revealed a marker c h r o m o s o m e due to translocation between c h r o m o s o m e s # 3 and #7. Patient 12 (L. W.). The marrow cells obtained at the time of diagnosis s h o w e d a normal karyotype: 46,XY. The patient relapsed 11 months later, and at that time, cytogenetic examination revealed the presence of an additional segment on the long arm of chromosome #21. This a n o m a l y was the result of a translocation b e t w e e n the short arm of c h r o m o s o m e # 9 (breakpoint at p13) and the long arm of chromosome #21 (breakpoint at q13) (Fig. 5), Patient 13 (M. C.). The m o d a l c h r o m o m s o m e n u m b e r was 46, but b a n d i n g revealed an abnormal karyotype with deletion of the short arm of c h r o m o s o m e #1 (breakpoint at p32) and translocation of this segment to the short arm of c h r o m o s o m e #12 (breakpoint) at p12) (Fig. 6). Patient 14 (M. W.). The bone marrow s p e c i m e n from this patient was of very poor quality. The cytogenetic examination revealed cells with 52 chromosomes, as well as normal ones with the karyotype 46,XY. Banding analysis to determine the exact
Figure 5
Karyotype of case 12 with a translocation, t(9p;21q), in relapsed bone marrow.
Cytogenetic Findings in Childhood ALL
Figure 6
55
Karyotype of case 13: 46,XX,t(1;12)(p32;p12) (arrows).
origin of the extra chromosomes was unsuccessful. Despite this, we decided to include this patient in the study, particularly for analysis of the clinical significance of chromosomal abnormalities in ALL. Patient 15 (M. J.). The initial chromosome study showed a normal karyotype, 46,XY, in the bone marrow cells. After 4.5 years, a follow-up study showed about 50% of the metaphases to have an abnormal karyotype, with chromosome #19 missing. The patient had gone through several central nervous system relapses, but was still in bone marrow remission. Patient 16 (P. M.). A bone marrow obtained at the time of diagnosis was shown to have polyploid cells containing 55 chromosomes in addition to chromosomally normal cells. The cells with 55 chromosomes had extra chromosomes #2, #4, #9, #14, #15, #19, #20, and two #21s. Patient 17 (P. J.). The modal chromosome number was 46. Banding analysis showed an interstitial deletion of the long arm of chromosome #5. Two and onehalf years later, the patient relapsed, and karyotypic evolution of the previous anomaly could be observed in cells with 45 chromosomes, where chromosome #5 was missing.
56
J.R. Kowalczyk et al.
Patient 18 (B. R.). The marrow contained cells with a m o d e of 46 chromosomes. However, b a n d i n g analysis showed one # 7 c h r o m o s o m e with an extra segment on its long arm. The extra segment seemed to be originated from the long arm of chrom o s o m e #1 (Fig. 7). Patient 19 (B. D.). The m o d a l c h r o m o s o m e n u m b e r in the first study was 46, with a normal karyotype. At the time of the third relapse, clonal abnormalities were observed in a d d i t i o n to k a r y o t y p i c a l l y normal cells. Banding revealed the abnormal metaphases to be p s e u d o d i p l o i d and to contain an interstitial deletion of the long arm on chromosome #5, a missing chromosome #20, and an extra marker chromosome, w h i c h was an i s o c h r o m o s o m e of the long arm of #17 (Fig. 8). Patient 20 (B. K.). A bone marrow s p e c i m e n was shown to contain a mixture of cells with about half of the ceils having a normal d i p l o i d karyotype and the other half being p s e u d o d i p l o i d due to loss of a chromosome # 5 and an extra chromosome #17.
Figure 7 (case 18).
Trisomic part of the long arm of #1 (arrow) translocated to the long arm of #7
Cytogenetic Findings i n Childhood ALL
57
Figure 8 Pseudadiploid karyotype of case 19 showing an interstitial deletion of chromosome #5 (5q-) and an isochromosome for 17q, i(17q) (arrows).
Patient 21 (B. T.). In this patient, clonal evolution of cytogenetic abnormalities was seen during the course of the disease. The first examination showed a normal karyotype, 46,XX, in the bone marrow cells. After the patient relapased 17 months later, in addition to normal metaphases, abnormal ones were observed, with one X chromosome missing and a modal chromosome n u m b e r of 45. Cytogenetic study during the second relapse showed an additional abnormality resulting from deletion of the short arm of a chromosome #17 (breakpoint at p11). One m o n t h later, additional abnormalities were found, i.e., an extra chromosome #20, missing #21 and #22, and a marker chromosome originating from a translocation between the long arms of chromosomes #21 and #22 (Fig. 9).
Patient 22 (B. W.). The marrow cells contained a mode of 46 chromosomes. All cells studied with b a n d i n g had a deletion of the long arm of a chromosome # 6 at breakpoint q23. A few metaphases having 47 chromosomes were observed, due to an extra chromosome # 8 in addition to the deleted #6.
Patient 23 (F. R.). The modal chromosome n u m b e r was 51. The extra chromosomes were #4, #9, #16, #17, and two #21s and an u n k n o w n marker chromosome;
58
J.R. Kowalczyk et al.
Figure 9 Karyotype of bone marrow cell from patient B.T. (case 21) in second relapse: 45,X,del(17)(p11), + 20,t(21q;22q) (arrows).
chromosomes # 7 and #12 were missing. In addition, a deletion of the long arm of chromosome #1 was observed (breakpoint q41), with the deleted segment being translocated to the long arm of the other chromosome #1 (breakpoint q25). Most cells k a r y o t y p e d also had a deletion of the short arm of a c h r o m o s o m e # 9 (Fig. i0). P a t i e n t 24 (H. K.). This case has been reported in detail in a previous paper [8].
The first chromosomal study of the bone marrow showed that the m o d a l chromosome n u m b e r was 54, but that there was a substantial number of cells with 27 chromosomes, as well as normal cells. The cells with 27 chromosomes had only one c h r o m o s o m e in each pair, except for pairs #10, #14, #18, and #21. The # 7 chromosome was structurally changed, with additional segments from an u n k n o w n chromosome having been translocated to the distal end of its short arm. Therefore, normal chromosomes # 7 were not observed. The cells with 54 c h r o m o s o m e s contained an exact d u p l i c a t i o n of the set found in the cells with 27 chromosomes. Six months later, w h e n the patient was in relapse following complete remission, a bimodal c h r o m o s o m e n u m b e r of 27 and 46 was found in bone marrow. All of the cells with 27 chromosomes had a normal # 7 chromosome. In two cells with 54 chromosomes, w h i c h contained exact d u p l i c a t i o n of the cells with 27 c h r o m o s o m e s from the same specimen, both # 7 s chromosomes were normal.
Cytogenetic Findings in Childhood ALL
59
Figure 10 Hyperdiploid karyotype of case 23: 51,XY,t(1;1)(q41;q25),+4,del(6)(q21),-7,+9, de19(p13),- 12, + 16, + 17, + 21, + 21, + mar.
Patient 25 (H. D.). A bone marrow s p e c i m e n had been shown to have a m o d e of 46 chromosomes. Detailed analysis of b a n d e d karyotypes revealed an abnormal chromosome #6, due to deletion of the long arm at the breakpoint q21, and an abnormal #9, due to deletion of the short arm (breakpoint p11) (Fig. 11).
Karyotypic Evolution In four children, the first cytogenetic examinations revealed normal karyotypes in the bone marrow, however, chromosomal abnormalities of a clonal nature were observed in relapse. In an additional eight children, clanal evolution of previous abnormalities could also be observed during the course of disease, These data are presented in Table 4.
DISCUSSION In the present study, clonal abnormalities in bone marrow cells were identified in 59.5% of c h i l d r e n with ALL. This percentage is slightly higher than that observed by Oshimura et al. [2], Cimino et al. [1], and S w a n s b u r y et al. [4] and is slightly
60
J.R. Kowalczyk et al.
Figure 11 Karyotype of case 25 showing deletions of the long arm of chromosome #6 and of the short arm of #9. lower than that reported by Williams et al. [9]. However, it is in good agreement with a more extensive survey of the Third International Workshop on Chromosomes in Acute Leukemia, where 62% of the children with ALL showed chromosomal abnormalities [5]. One can expect that, with improvements of banding techniques and other cytogenetic methods for chromosomal analysis of leukemic cells, the percentage of ALL patients with chromosomal aberrations in the initial bone marrow cells may be higher [10]. Generally, it is thought that hypodiploidy is rather rare in ALL [2, 4, 5]. The present study revealed 6 patients (14.3%) with a modal chromosome number less than 46. Recently, Arthur et al. [11] have also found a significant number of hypodiploid clones among their patients with ALL. In 23.8% of our patients, we observed pseudodiploidy. A somewhat higher figure was seen by other authors, from 29.9% to 33% [5, 11, 12]. This fact emphasizes the necessity of chromosome banding examination in all leukemic patients, even if a normal number of chromosomes is found with standard Giemsa staining. Differences exist between laboratories regarding the frequency of structural chromosomal changes in ALL. Two previous papers stated that 12% and 22.9% of patients with ALL had structural abnormalities [5, 13]. In our study, 38% of children had structural rearrangements, and the most frequent were translocations in 13 children, i.e., in more than a half of the patients with chromosomal aberrations. Almost all chromosomes were involved in changes except for chromosome #11
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62
J . R . K o w a l c z y k et al.
and the Y. Table 5 p r e s e n t s the d i s t r i b u t i o n of aberrations a m o n g the c h r o m o s o m e groups. C h r o m o s o m e # 2 1 was i n v o l v e d m o s t frequently. Different t y p e s of rearr a n g e m e n t s of this c h r o m o s o m e w e r e o b s e r v e d in a l m o s t half of ALL c h i l d r e n w i t h c h r o m o s o m a l aberrations. C h r o m o s o m e s # 7 , # 9 , a n d # 1 7 w e r e i n v o l v e d in a l m o s t o n e - t h i r d of p a t i e n t s a n d c h r o m o s o m e s # 5 , # 6 , and # 1 4 in about 25% of the children. T h e s e findings are in partial a g r e e m e n t w i t h p r e v i o u s reports of O s h i m u r a et al. [2], w h o f o u n d c o m m o n i n v o l v e m e n t of # 2 1 and #6. In the s u r v e y by M i t e l m a n and L e v a n [14], c h r o m o s o m e s # 6 , # 7 , # 1 4 , # 1 7 , and # 2 1 w e r e m o s t f r e q u e n t l y i n v o l v e d , and in the r e p o r t of A r t h u r et al. [11], c h r o m o s o m e s # 6 , # 9 , # 1 4 , and # 2 1 w e r e the m o s t frequent. T h e s e data afford s o m e e v i d e n c e r e g a r d i n g the p o s s i b l e n o n r a n d o m d i s t r i b u t i o n of c h r o m o s o m a l abn o r m a l i t i e s in ALL. It s e e m s that c h r o m o s o m e s # 6 , # 7 , # 9 , # 1 4 , # 1 7 , a n d # 2 1 in ALL-affected b o n e m a r r o w cells are n o n r a n d o m l y i n v o l v e d in r e a r r a n g e m e n t s d u r i n g the c o u r s e of disease. It s h o u l d also be p o i n t e d out that s o m e specific chrom o s o m a l c h a n g e s are r e l a t i v e l y c o m m o n in ALL. P r e v i o u s reports p r e s e n t e d the f r e q u e n t o c c u r r e n c e of a d e l e t i o n of the l o n g arm of a c h r o m o s o m e # 6 [2, 11, 14]. In the p r e s e n t study, w e h a v e f o u n d 4 p a t i e n t s w i t h this aberration, t h o u g h the b r e a k p o i n t s w e r e not the same. It is w o r t h n o t i n g that, in our study, 3 of 4 p a t i e n t s w i t h 6 q - w e r e male. A r t h u r et al. [11] h a v e also f o u n d p r e d o m i n a n t l y m a l e s (5 of 6) w i t h this a b n o r m a l i t y .
Table 5
I n v o l v e m e n t of c h r o m o s o m e groups in p a t i e n t s w i t h ALL w h o h a v e c h r o m o s o m e abnormalities Chromosome number
Patient (1) (2) (3) (4)
1
2
3
4
5
A.M. B.M. G.G. H.W,
(5) S.R.
6
7
+ +
+ +
+
8
10 11 12 13 14 15 16 17 18 19 20 21 22 X Y
+ +
+ +
+
+ +
+
+ + + +
+ +
+
[6) S.E.
+
+ +
+
+
(7) c.P.
+
(8)
D.H. (9) S.T.
(10) G.D. (11) I.T. (12) L.W. (13) M.C. (14) M.W. (15) M.J. (16) P.M. (17) P.J. (18) B.R. (19) B.D, (20) B.K. (21) B.T, (22) B.W. (23] F.R, (24) H.K. (25) H.D. Total
9
+
+ +
+
+ +
+
+
+
+ +
+
+
+
+
+
+
+
+
+
+ +
+
+
+
+
+
+
+
+ +
+
+
+
+ +
+ + +
+
3
+ +
+
2
4
2
+ + +
6
+ 6
+ +
+
+
+
12 3
3
+ + + 8
+
+
+
+ 2
+ 7
4
+
+ 0
2
3
5
+ +
+ 2
4
6
2
2
3
Cytogenetic Findings in C h i l d h o o d ALL
63
Evolution of the karyotype occurred in 12 of the 25 patients with aneuploidy. In some cases, two or more clones were already present at the initial study; in other patients, only one clone was shown to exist at the time of diagnosis. All these patients had normal karyotypes in bone marrow cells during remission. After the patients relapsed, clones with previously observed abnormalities were generally found again, but w i t h some additional rearrangements. These findings seemed to represent cytogenetically more a d v a n c e d changes. Contrary to previous data [2], our material does not s h o w a t e n d e n c y to increased c h r o m o s o m e numbers during karyotypic evolution. Rather, we observed structural rearrangements to be the more frequent a d d i t i o n a l changes. So far, we have failed to find specific chromosomes involved in the genesis of these karyotypic changes [1, 2, 15, 16]. However, we w o u l d like to m e n t i o n two examples of karyotypic evolution in our material. A n interesting case is patient 7, who had a karyotype with a 5 q - as the p r i m a r y change and then, during the progress of disease, the cells were missing a c h r o m o s o m e # 5 c o m p l e t e l y (Table 4). Generally, in contrast to the rather c o m m o n evolution of - 7 from 7 q - , the loss of a c h r o m o s o m e #5 subsequent to the appearance of 5 q - is rather rare. It will be interesting to ascertain whether the same situation will develop in the following examinations in patient 8, w h o presently has a 5 q - chromosome. There were two other cases with a missing # 5 chromosome: at the time of diagnosis in one patient and during relapse in the other. However, we failed to find a 5 q - c h r o m o s o m e in the cells of the same bone marrow s p e c i m e n in both cases. Another interesting karyotypic evolution occurred in two cases (patients 2 and 11 of Table 4) with the above-mentioned deletion of 6q. In these cases, the a n o m a l y a p p e a r e d during the evolution of the karyotype as an a d d i t i o n a l aberration. The group of c h i l d r e n with ALL presented in this article is of special interest in correlating the various c h r o m o s o m e abnormalities with their clinical significance, as all the patients were p l a c e d on the same treatment protocol. In the second article in this series, we will present results of a correlation of findings with the clinical course, survival, and laboratory data of these patients. Supported in part by Public Health Service International Research Fellowship F05 TWO300901 to J.R.K.
REFERENCES 1. Cimino MC, Rowley JD, Kinnealey A, Variakojis D, Golomb HM (1979): Banding studies of chromosomal abnormalities in patients with acute lymphocytic leukemia. Cancer Res 39:227-238. 2. Oshimura M, Freeman AI, Sandberg AA (1977): Chromosomes and causation of human cancer and leukemia. XXVI. Banding studies in acute lymphoblastic leukemia (ALL). Cancer 40:1161-1172. 3. Rowley JD (1980): Chromosome abnormalities in acute lymphoblastic leukemia. Cancer Genet Cytogenet 1:263-271. 4. Swansbury GJ, Secker-Walker LM, Lawler SD, Hardisty RM, Sallen SE, Garson OM, Sakurai M (1981): Chromosomal findings in acute lymphoblastic leukaemia of childhood: An independent prognostic factor. Lancet 2:249-250. 5. Third International Workshop on Chromosomes in Acute Leukemia (1981): Clinical significance of chromosomal abnormalities in acute lymphoblastic leukemia. Cancer Genet Cytogenet 4:95-142. 6. Sandberg AA (1980): The Chromosomes in Human Cancer and Leukemia, Elsevier/North Holland, New York. 7. Paris Conference (1971): Standardization in human cytogenetics. Birth Defects 8:00.
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8. Oshimura M, Freeman AI, Sandberg AA (1977): Chromosomes and causation of human cancer and leukemia. XXIII. Near-haploidy in acute leukemia. Cancer 40:1143-1148. 9. Williams DL, Tsiatis A, Brodeur GM, Look AT, Melvin SL, Bowman WP, Kalwiusky DK, Rivera G, Dahl GV (1982): Prognostic importance of chromosome number in 136 untreated children with acute lymphoblastic leukemia. Blood 60:864. 10. Yunis JJ, Bloomfield CD, Ensrud K (1981): All patients with acute nonlymphocytic leukemia may have a chromosomal defect. N Engl J Med 305:135-139. 11. Arthur DC, Bloomfield CD, Lindquist LL, Peterson BA, Nesbit ME (1981): Chromosome abnormalities in acute lymphoblastic leukemia (ALL): Frequency and clincial implications. Proc AACR 3:345. 12. Kaneko Y, Rowley JD (1981): Correlation of karyotype with prognosis in acute lymphocytic leukemia (ALL). Proc AACR 3:338. 13. Brodeur GM, Williams DL, Bowman WP, Look AT, Kalwinsky DK, Aur RJA, Rivera G, Dahl GV (1981): Cytogenetic features of acute lymphoblastic leukemia (ALL) in children. Proc AACR 3:45. 14. Mitelman F, Levan G (1978): Clustering of aberrations to specific chromosomes in human neoplasms. Hereditas 89:207-232. 15. Whang-Peng J, Knutsen T, Ziegler J, Leventhal B (1976): Cytogenetic studies in acute lymphocytic leukemia- Special emphasis on long-term survival. Med Pediatr Oncol 2:333351. 16. Zuelzer WW, Inoue S, Thompson, RE, Ottenbreit M (1976): Long-term cyt0genetic studies in acute leukemia of children; the nature of relapse. Am J Hematol 1:143-190.