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Is chorionic villus sampling as reliable as amniocentesis?
CYTOGENETICS IS CHORlONlC VILLUS SAMPLING AS RELIABLE AS AMNIOCENTESIS? Mark D Pertile, Jacinta T Ryan, Cytogenetics Unit, Royal Women's Hospital, Melbourne, Victoria 3053. A comprehensive review of 1230 long term (LT) cultured chorionic villus samples (CVS) shows the technique to be exceptionally reliable. Excluding the three to four fold increase in the reported incidence of mosaicism in CVS. LT culture provides rapid results which are as accurate a s those obtained from amniotic fluid cell culture. Experience and expertise play an important role in the successful implementation of the LT technique.
Cytogenetic results were successfully obtained from 99.7% of samples. Maternal cell contamination (ME),often reported as a complication of LT culture, was observed at a frequency of 0.24%. This ligure compares favourably to frequencies of MCC reported in collaborative studies d amniotic fluid cell culture (0.15 - 0.30%). Abnormal cytogenetic results (excluding mosaics) were reported on 52 occasions. No case of discordance was observed be%een fetal abortus products and the prenatal cytogenetic finding. Mosaicism was observed in two or more independent cultures on nine occasions (0.73%).Seven of the nine pregnancies underwent amniocentesis while two pregnancies continued without further invesrigation. Confined placental mosaicism (CPM) is suspected in 8 of the 9 cases. The effect of CPM, if any, remains largely unknown. The importance of establishing at least two independent cultures isdiscussed in relation to minimisingthe need for additional prenatal testing. Sensible pregnancy management by clinical genetic staff can further reduce the need for amniocentesis, particularly in cases where non viable mosaic trisomies are detected.
THE IMPACT
iF MOLECULAR B i u L G Y ON TIiE DEFINITION OF HLA
POLYMORPHISM AN0 ITS CLINICAL APPciCATION.
B . 0. Tait, Tissue Typlng Laboratory, Royal Melbourne Hospiral,
Parkville, Vic 3052.
Seroiogy has been the cornerstone technique f o r detection o f HLA pol-morphisoi since the first HLA c l a s s I allele was describe6 in 1958. T h e application o f HLA i:,dtching in clinical transplantation has relied tnereiore on the m a h i i n g of serological epitopes on botti class 1 dnd class i I molecules. More r e c e n t i , sequencing d a t a h d 5 revealed that the serologicai specificitieb ai'e public m i t o p e s found on several allellc variants, t h ? j being particularly 50 f o r the Class I 1 molecules. HLA matching f o r - t i d n s ~ l ~ n t a t i o historically n therefore has bezn an imprecise science. More recent',) the inti-oabction o f the polymerase chain r e a c L i o i i f o r amplification o f Class I 1 genes and the use o f short oilgoprobes f o r detection o f variable regions n o t defined by serological reayents nas allowed a more dlscriminating dnalysis o f polymorphism and has opened up the possibility of applying this method i n matching f o r clinical transplantation, particularly hone marrow rransp1anta:ion. T h e use o f one uiineiis 1 1 i w - e l e ~ t ~ ' i cf o c u s i n g likewise has revfaied add:tiondl ~ 1 b > : , i : ~ ~ I , , t ~ , : + : i i!\a; j , $ deflned by Serology wiiich also appear t i have ..rlevance ,ii iransp1anta:ion.
APPLICATION OF THE POLYMERASE CHAIN REACTION T O DETECTION OF MINIMAL RESIDUAL DISEASE. A. Morley, Department of Haematology, Medical Centre, Bedford Park, S.A. 5042.
F1 inders
The exquisite sensitivity of the polymerase chain reaction makes it potentially possible to detect a small population of neoplastic cells provided that they contain DNA or RNA which differs from the nonneoplastic population. For haemopoietic cells, this situation obtains for translocations, for the rearranged immunoglobul in and T-cell receptor genes o f B or T disorders, for mutated oncogenes such as ras, and for repetitive segments of DNA.
In this presentation the technical aspects of detection of minimal residual disease will be discussed using examples from the above areas. The clinical value of detection of minimal residual disease is a separate issue which will be resolved over the next few years. However, it does seem 1 ikely that important information on the biology, treatment and prognosis of haematological neoplasms will be obtained. Presenter: Prof. A1 ec Morl ey, Haematol ogy Department, FMC .
PROGNOSTIC VALUE OF IMMUNOPHENOTYPING I N ACUTE LEUKAEMIA Ken B r a d s t o c k . Haenatology Dept.. Westmead Hospit a l , NSU, A u s t r a l i a . Immunophenotyping w i t h monoclonal a n t i b o d i e s , e i t h e r by i m n u n o f l u o r e s c e n t flow c y t o m e t r y or immunocytochenistry i s now of proven d i a g n o s t i c v a l u e i n a c u t e leukaemia. Although s u r f a c e marker a n a l y s i s h a s g r e a t l y enhanced o u r u n d e r s t a n d i n g of t h e b i o l o g i c a l b a s i s of a c u t e l e u k a e n i a . t h e p r o g n o s t i c s i g n i f i c a n c e of t h i s informat i o n remains l a r g e l y c o n t r o v e r s i a l . The i m p o r t a n c e of r e c o g n i t i o n o f v a r i a n t s o f ALL h a s a l t e r e d w i t h i m proved chemotherapy p r o t o c o l s , and t h e s i g n i f i c a n c e of v a r i o u s myeloid l i n e a g e markers in AML is u n c e r t a i n . The r e c o g n i t i o n of l i n e a g e i n f i d e l i t y i n a c u t e l e u k a e mia i s p o t e n t i a l l y more s i g n i f i c a n t . Among s e v e r a l hundred c a s e s of a c u t e l e u k a e n i a t e s t e d i n our l a b o r a t o r y , e x p r e s s i o n of t h e myeloid d i f f e r e n t i a t i o n a n t i gens CD-llb, CD-13, and CD-33 was d e t e c t e d i n 5-11% of c a s e s of p r e c u r s o r -B ALL, w h i l e t h e lymphoid markers CD-2, CD-7 and TdT were found i n lo%, 28% and 22% of c a s e s o f AML r e s p e c t i v e l y . R e p o r t s of t h e c l i n i c a l s i g n i f i c a n c e of myeloid a n t i g e n e x p r e s s i o n i n ALL v a r y , a l t h o u g h t h i s phenomenon h a s been r e c e n t l y claimed t o be a major a d v e r s e p r o g n o s t i c f a c t o r i n b o t h p a e d i a t r i c and a d u l t p a t i e n t s . T h e r e is a l s o e v i d e n c e t h a t c a s e s of AML w i t h e x t e n s i v e lymphoid a n t i g e n e x p r e s s i o n have a poor outcome. F u r t h e r c l a r i f i c a t i o n of t h e s i g n i f i c a n c e of l i n e a g e i n f i d e l i t y w i l l r e q u i r e a n a l y s i s of innunophenotyping d a t a from l a r g e c l i n i c a l t r i a l s .
Cytogenetic results were successfully obtained from 99.7% of samples. Maternal cell contamination (ME),often reported as a complication of LT culture, was observed at a frequency of 0.24%. This ligure compares favourably to frequencies of MCC reported in collaborative studies d amniotic fluid cell culture (0.15 - 0.30%). Abnormal cytogenetic results (excluding mosaics) were reported on 52 occasions. No case of discordance was observed be%een fetal abortus products and the prenatal cytogenetic finding. Mosaicism was observed in two or more independent cultures on nine occasions (0.73%).Seven of the nine pregnancies underwent amniocentesis while two pregnancies continued without further invesrigation. Confined placental mosaicism (CPM) is suspected in 8 of the 9 cases. The effect of CPM, if any, remains largely unknown. The importance of establishing at least two independent cultures isdiscussed in relation to minimisingthe need for additional prenatal testing. Sensible pregnancy management by clinical genetic staff can further reduce the need for amniocentesis, particularly in cases where non viable mosaic trisomies are detected.
THE IMPACT
iF MOLECULAR B i u L G Y ON TIiE DEFINITION OF HLA
POLYMORPHISM AN0 ITS CLINICAL APPciCATION.
B . 0. Tait, Tissue Typlng Laboratory, Royal Melbourne Hospiral,
Parkville, Vic 3052.
Seroiogy has been the cornerstone technique f o r detection o f HLA pol-morphisoi since the first HLA c l a s s I allele was describe6 in 1958. T h e application o f HLA i:,dtching in clinical transplantation has relied tnereiore on the m a h i i n g of serological epitopes on botti class 1 dnd class i I molecules. More r e c e n t i , sequencing d a t a h d 5 revealed that the serologicai specificitieb ai'e public m i t o p e s found on several allellc variants, t h ? j being particularly 50 f o r the Class I 1 molecules. HLA matching f o r - t i d n s ~ l ~ n t a t i o historically n therefore has bezn an imprecise science. More recent',) the inti-oabction o f the polymerase chain r e a c L i o i i f o r amplification o f Class I 1 genes and the use o f short oilgoprobes f o r detection o f variable regions n o t defined by serological reayents nas allowed a more dlscriminating dnalysis o f polymorphism and has opened up the possibility of applying this method i n matching f o r clinical transplantation, particularly hone marrow rransp1anta:ion. T h e use o f one uiineiis 1 1 i w - e l e ~ t ~ ' i cf o c u s i n g likewise has revfaied add:tiondl ~ 1 b > : , i : ~ ~ I , , t ~ , : + : i i!\a; j , $ deflned by Serology wiiich also appear t i have ..rlevance ,ii iransp1anta:ion.
APPLICATION OF THE POLYMERASE CHAIN REACTION T O DETECTION OF MINIMAL RESIDUAL DISEASE. A. Morley, Department of Haematology, Medical Centre, Bedford Park, S.A. 5042.
F1 inders
The exquisite sensitivity of the polymerase chain reaction makes it potentially possible to detect a small population of neoplastic cells provided that they contain DNA or RNA which differs from the nonneoplastic population. For haemopoietic cells, this situation obtains for translocations, for the rearranged immunoglobul in and T-cell receptor genes o f B or T disorders, for mutated oncogenes such as ras, and for repetitive segments of DNA.
In this presentation the technical aspects of detection of minimal residual disease will be discussed using examples from the above areas. The clinical value of detection of minimal residual disease is a separate issue which will be resolved over the next few years. However, it does seem 1 ikely that important information on the biology, treatment and prognosis of haematological neoplasms will be obtained. Presenter: Prof. A1 ec Morl ey, Haematol ogy Department, FMC .
PROGNOSTIC VALUE OF IMMUNOPHENOTYPING I N ACUTE LEUKAEMIA Ken B r a d s t o c k . Haenatology Dept.. Westmead Hospit a l , NSU, A u s t r a l i a . Immunophenotyping w i t h monoclonal a n t i b o d i e s , e i t h e r by i m n u n o f l u o r e s c e n t flow c y t o m e t r y or immunocytochenistry i s now of proven d i a g n o s t i c v a l u e i n a c u t e leukaemia. Although s u r f a c e marker a n a l y s i s h a s g r e a t l y enhanced o u r u n d e r s t a n d i n g of t h e b i o l o g i c a l b a s i s of a c u t e l e u k a e n i a . t h e p r o g n o s t i c s i g n i f i c a n c e of t h i s informat i o n remains l a r g e l y c o n t r o v e r s i a l . The i m p o r t a n c e of r e c o g n i t i o n o f v a r i a n t s o f ALL h a s a l t e r e d w i t h i m proved chemotherapy p r o t o c o l s , and t h e s i g n i f i c a n c e of v a r i o u s myeloid l i n e a g e markers in AML is u n c e r t a i n . The r e c o g n i t i o n of l i n e a g e i n f i d e l i t y i n a c u t e l e u k a e mia i s p o t e n t i a l l y more s i g n i f i c a n t . Among s e v e r a l hundred c a s e s of a c u t e l e u k a e n i a t e s t e d i n our l a b o r a t o r y , e x p r e s s i o n of t h e myeloid d i f f e r e n t i a t i o n a n t i gens CD-llb, CD-13, and CD-33 was d e t e c t e d i n 5-11% of c a s e s of p r e c u r s o r -B ALL, w h i l e t h e lymphoid markers CD-2, CD-7 and TdT were found i n lo%, 28% and 22% of c a s e s o f AML r e s p e c t i v e l y . R e p o r t s of t h e c l i n i c a l s i g n i f i c a n c e of myeloid a n t i g e n e x p r e s s i o n i n ALL v a r y , a l t h o u g h t h i s phenomenon h a s been r e c e n t l y claimed t o be a major a d v e r s e p r o g n o s t i c f a c t o r i n b o t h p a e d i a t r i c and a d u l t p a t i e n t s . T h e r e is a l s o e v i d e n c e t h a t c a s e s of AML w i t h e x t e n s i v e lymphoid a n t i g e n e x p r e s s i o n have a poor outcome. F u r t h e r c l a r i f i c a t i o n of t h e s i g n i f i c a n c e of l i n e a g e i n f i d e l i t y w i l l r e q u i r e a n a l y s i s of innunophenotyping d a t a from l a r g e c l i n i c a l t r i a l s .