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Tissue-specific mosaicism for trisomy 21 and congenital heart disease
80
Clinical and laboratory observations
The normality of the 3/-GT level has subsequently been perceived as an important criterion in the diagnosis of this severe disorder. Our cases show that benign intrahepatic cholestasis also may be associated with normal 3,-GT activity in the infant during the first weeks of life. Although specific clinical or laboratory diagnosis of BRC or of Byler disease at this age is not possible, it is important to make a distinction between the two diseases as early as possible, as soon as serious unfavorable factors are recognized; pathologic signs and biologic markers associated with the syndrome of cholestasis itself should be taken into account, together with a search for similar cases in the patient's family.
The Journal of Pediatrics July 1992
2. 3.
4.
5.
tivity identifies groups of infants with idiopathic cholestasis with poor prognosis. J PEDIATR1987;111:251-3. Summerskill WHJ, Walshe JM. Benign recurrent intrahepatic obstructive jaundice. Lancet 1959;1:686-90. Bijleveld CMA, Vonk R J, Kuipers F, et al. Benign recurrent intrahepatic cholestasis: altered bile acid-metabolism. Gastroenterology 1989;97:427-32. Maggiore G, Bernard O, Hadchouel M, et al. Diagnostic value of serum 3,-glutamyl transpeptidase activity in liver diseases in children. J Pediatr Gastroenterol Nutr 1991;12:21-6. de Pagter AG, Van Berge Henegouwen GP, Ten Bokkel Huinin JA, et al. Familial benign recurrent intrahepatic cholestasis: interrelation with intrahepatic cholestasis of pregnancy and from oral contraceptives? Gastroenterology 1976;71:202-7.
REFERENCES
1. Maggiore G, Bernard O, Riely CA, Hadchouel M, Lemonnier A, Alagille D. Normal serum 7-glutamyl-transpeptidase ac-
Tissue-specific mosaicism for trisomy 24 and congenital heart disease Yuji Yokoyama, MD, Kouji Narahara, MD, Masahiro Kamada, MD, Kazushiro Tsuji, MD, and Yoshiki Seino, MD From the Department of Pediatrics, Okayama University Medical School, Okayama, Japan
Cytogenetic studies in a girl with ventricular septal defect and mosaicism for trisomy 21 showed that trisomy was present in most cells from the myocardium and lung but in only a minority from the skin and lymphocytes. These findings emphasize the importance of tissue-specific mosaicism as a cause of certain cardiovascular diseases. (J PEDIATR4992;421:80-2)
Trisomy 21 accounts Ior the chromosome abnormality m the majority of patients with Down syndrome; mosaic trisomy 21 is found in only about 3%. 1 The phenotypes of patients with mosaic karyotypes are usually milder than those of patients with simple trisomy 21. We saw a patient with DS and low-level mosaicism for trisomy 21 who had a ventricular septal defect of the endocardial cushion type. Cy-
togenetic studies'bf various tissues obtained at the time of open heart surgery showed that trisomy 21 was present in most cells from the myocardium and lung but in only a minority of those from the skin and peripheral blood lymphocytes.
VSD Submitted for publication Dec. 6, 1991; accepted Feb. 25, 1992. Reprint requests: Yuji Yokoyama, MD, D~artment of Pediatrics, Okayama UniversityMedical School, Shikata-cho 2-5-1, Okayama 700, Japan. 9/22/37453
Down syndrome Ventricular septal defect
]
CASE R E P O R T The female patient was born at 38 weeks of gestation to a 25-year-old para 1, gravida 2 mother and a 30-year-old father. There was no family history of mental retardation or multiple con-
Volume 121 Number 1
Clinical and laboratory observations
81
Figure. Transmission of chromosomes 21 from father (P) and mother (M) to trisomic cell line (T) and to diploid cell line (D) of the patient (QFQ-banding).
genital anomalies. The parents and an older sibling were healthy. The pregnancy and delivery were uneventful; birth weight was 1920 gm. The patient required incubator care during the first month of life. The following anomalies were noted: upward-slanting palpebral fissures, hypertelorism, epicanthic folds, a flat nasal bridge, low-set and malformed ears with folded helices, short and stubby fingers, single transverse creases on both palms, and muscular hypotonia. Chromosome analysis of peripheral blood lymphocytes demonstrated a mosaic karyotype of 46,XX/47,XX, +21 (16%). At the age of 2 months, systolic murmurs became evident over the patient's left sternal area. Her psychomotor development was mildly retarded. Cardiac ultrasonography and catheterization at
the age of 4 years showed a ventricular septal defect of the endocardial cushion type, patent ductus arteriosus, and pulmonary hypertension. At the age of 5 years 2 months, the patient underwent corrective open heart surgery. CYTOGENETIC
STUDIES
W i t h informed consent of the parents, cytogenetic studies were performed on peripheral blood lymphocyte cultures from the patient and her parents. Fibroblasts were also cultured from samples of the m y o c a r d i u m , lung, a n d skin of the anterior portion chest, obtained at the time of open h e a r t
82
Clinical and laboratory observations
surgery. The samples were minced into small pieces and then cultured in Eagle minimal essential medium supplemented with 15% fetal calf serum and antibiotics under an atmosphere of 5% carbon dioxide. Chromosome analysis was made at the second passage of the cultures. Chromosome preparations were subjected to GTG- and QFQbanding. In all tissues of the patient, two cell lines with 46,XX or 47,XX, +21 existed9 However, the ratio of trisomic cells varied from one tissue to another: 90.5% (38/42) in the myocardium, 72.7% (16/22) in the lung, 339 (10/30) in the skin, and 3.8% (9/233) in the peripheral blood lymphocytes. The trisomic cell line had three different chromosomes 21, with the short-arm morphology differing from each other on GTG- and QFQ-banding; the normal cell line had two different chromosomes 21. QFQ-banding analysis of polymorphisms on the short arm of chromosome 21 showed that the mosaicism in this patient resulted from mitotic nondisjunctionin the trisomic conceptus (Figure). The parental origin of the trisomy could not be determined; the parents had normal chromosomes. DISCUSSION This patient with mosaic trisomy 21 is interesting not only in that she had VSD of the endocardial cushion type, a malformation seldom associated with this type of chromosomal aberration, but also in that tissue-limited mosaicism was evident cytogenetically. Furthermore, study of the short-arm polymorphisms on chromosome 21 demonstrated that the mosaicism arose as a consequence of nondisjunction in the trisomic conceptus. In view of the fact that endocardial cushion defect (or VSD of the endocardial cushion type) and pulmonary hypertension are specifically associated with DS, 2 the occurrence of a cardiac defect in this patient may be related to the predominance of trisomy 21 in the heart and lung tissues. Recently the concept of tissue-specific mosaicism has attracted much attention. It is exemplified by studies on tetrasomy 12p mosaicism in the Pallister-Killian syndrome,3 mosaicism confined to villus cytotrophoblasts,4 and chromosome mosaicism in hypomelanosis of Ito. 5 Trisomy 4 or 16 mosaicism confined to skin fibroblasts has also been reported i n malformed live-born infants.6, 7 In this context, chromosome studies on various tissues are needed during the cytogenetic evaluation of patients with mental retardation and congenital multiple anomalies of an unclear cause. The difference in selection or tolerance in different tissues has been invoked to explain the occurrence of hssue-speclfiC mosaicism.8 The ratio of trisomic cells may decrease with
The Journal of Pediatrics July 1992
advancing age in peripheral blood lymphocytes of patients with mosaic DS. 9 In addition to endocardial cushion defect or VSD and pulmonary hypertension in trisomy 21, certain types of cardiovascular diseases have been reported to be specifically associated with certain types of chromosome abnormalities: coarctation of the aorta, bicuspid aortic valve, and hypoplastic left heart syndrome in monosomy X 2, 10; tetralogy of Fallot in dup(8q); total anomalous return of the pulmonary veins in pentasomy X; and patent ductus arteriosus in the cat-eye syndrome. 11 Although the cause of congenital heart disease is for the most part unknown, our observation suggests that localized mosaicism for a chromosome abnormality could be a cause of cardiac dysmorphogenesis. Particularly in patients with specific types of isolated cardiac malformation, cytogenetic study of a tissue specimen from the cardiovascular system appears to be warranted. REFERENCES
I. Stoll C, Alembik Y, Dott P, Roth MP. Epidemiologyof Down syndrome in 118,265 consecutive births. Am J Med Genet Suppl 1990;7:79-83. 2. Ferencz C, Neff CA, Boughman JA, Rubin JD, Brenner JI, Perry LW. Congenital cardiovascular malformations associated with chromosomeabnormalities: an epidemiologicstudy. J PEDIAT~1989;114:79-86. 39 Ward BE, Hayden MW, Robinson A. Isochromosome 12p mosaicism (Pallister-Killian syndrome): newborn diagnosis by direct bone marrow analysis. Am J Med Genet 1988;31: 835-99 4. Kalousek DK, Dill FJ, Pantzar T, MeGiUivrayBC, Yong SL, Wilson RD9 Confinedchorionic mosaicismin prenatal diagnosis. Hum Genet 1987;77:163-7. 5. Sybert VP, Pagon RA, Donlan M, Bradley CM. Pigmentary abnormalities and mosaicismfor chromosomal aberration: association with clinical features similar to hypomelanosisof Ito. J PEDIATR1990;116:581-6. 6. Marion JP, Fernhoff PM, Korotkin J, Priest JH. Pre- and postnatal diagnosis pf trisomy 4 mosaicism.Am J Med Genet 1990;37:362-5. 7. Gilbertson N J, Taylor JW, Kovar IZ. Mosaic trisomy 16 in a live newborn infant. Arch Dis Child 1990;65:388-9. 8. Hall JG. Somatic mosaicism: observations related to clinical genetics. Am J Hum Genet 1988;43:355-63. 9. Taylor AI. Further observationsof cell selection in vivoin normal/G trisomic mosaics. Nature 1970;227:163-4. 10. Larco RV, Jones KL, Benirschke K. Coarctation of the aorta in Turner syndrome:a pathologic study of fetuses with nuchal cystic hygromas, hydrops fetalis, and female genitalia. Pediatrics 1988;81:445-51. 11. Schinzel A. Catalogue of unbalanced chromosomeaberrations in man. Berlin, de Gruyter, 1984:853-4.
Clinical and laboratory observations
The normality of the 3/-GT level has subsequently been perceived as an important criterion in the diagnosis of this severe disorder. Our cases show that benign intrahepatic cholestasis also may be associated with normal 3,-GT activity in the infant during the first weeks of life. Although specific clinical or laboratory diagnosis of BRC or of Byler disease at this age is not possible, it is important to make a distinction between the two diseases as early as possible, as soon as serious unfavorable factors are recognized; pathologic signs and biologic markers associated with the syndrome of cholestasis itself should be taken into account, together with a search for similar cases in the patient's family.
The Journal of Pediatrics July 1992
2. 3.
4.
5.
tivity identifies groups of infants with idiopathic cholestasis with poor prognosis. J PEDIATR1987;111:251-3. Summerskill WHJ, Walshe JM. Benign recurrent intrahepatic obstructive jaundice. Lancet 1959;1:686-90. Bijleveld CMA, Vonk R J, Kuipers F, et al. Benign recurrent intrahepatic cholestasis: altered bile acid-metabolism. Gastroenterology 1989;97:427-32. Maggiore G, Bernard O, Hadchouel M, et al. Diagnostic value of serum 3,-glutamyl transpeptidase activity in liver diseases in children. J Pediatr Gastroenterol Nutr 1991;12:21-6. de Pagter AG, Van Berge Henegouwen GP, Ten Bokkel Huinin JA, et al. Familial benign recurrent intrahepatic cholestasis: interrelation with intrahepatic cholestasis of pregnancy and from oral contraceptives? Gastroenterology 1976;71:202-7.
REFERENCES
1. Maggiore G, Bernard O, Riely CA, Hadchouel M, Lemonnier A, Alagille D. Normal serum 7-glutamyl-transpeptidase ac-
Tissue-specific mosaicism for trisomy 24 and congenital heart disease Yuji Yokoyama, MD, Kouji Narahara, MD, Masahiro Kamada, MD, Kazushiro Tsuji, MD, and Yoshiki Seino, MD From the Department of Pediatrics, Okayama University Medical School, Okayama, Japan
Cytogenetic studies in a girl with ventricular septal defect and mosaicism for trisomy 21 showed that trisomy was present in most cells from the myocardium and lung but in only a minority from the skin and lymphocytes. These findings emphasize the importance of tissue-specific mosaicism as a cause of certain cardiovascular diseases. (J PEDIATR4992;421:80-2)
Trisomy 21 accounts Ior the chromosome abnormality m the majority of patients with Down syndrome; mosaic trisomy 21 is found in only about 3%. 1 The phenotypes of patients with mosaic karyotypes are usually milder than those of patients with simple trisomy 21. We saw a patient with DS and low-level mosaicism for trisomy 21 who had a ventricular septal defect of the endocardial cushion type. Cy-
togenetic studies'bf various tissues obtained at the time of open heart surgery showed that trisomy 21 was present in most cells from the myocardium and lung but in only a minority of those from the skin and peripheral blood lymphocytes.
VSD Submitted for publication Dec. 6, 1991; accepted Feb. 25, 1992. Reprint requests: Yuji Yokoyama, MD, D~artment of Pediatrics, Okayama UniversityMedical School, Shikata-cho 2-5-1, Okayama 700, Japan. 9/22/37453
Down syndrome Ventricular septal defect
]
CASE R E P O R T The female patient was born at 38 weeks of gestation to a 25-year-old para 1, gravida 2 mother and a 30-year-old father. There was no family history of mental retardation or multiple con-
Volume 121 Number 1
Clinical and laboratory observations
81
Figure. Transmission of chromosomes 21 from father (P) and mother (M) to trisomic cell line (T) and to diploid cell line (D) of the patient (QFQ-banding).
genital anomalies. The parents and an older sibling were healthy. The pregnancy and delivery were uneventful; birth weight was 1920 gm. The patient required incubator care during the first month of life. The following anomalies were noted: upward-slanting palpebral fissures, hypertelorism, epicanthic folds, a flat nasal bridge, low-set and malformed ears with folded helices, short and stubby fingers, single transverse creases on both palms, and muscular hypotonia. Chromosome analysis of peripheral blood lymphocytes demonstrated a mosaic karyotype of 46,XX/47,XX, +21 (16%). At the age of 2 months, systolic murmurs became evident over the patient's left sternal area. Her psychomotor development was mildly retarded. Cardiac ultrasonography and catheterization at
the age of 4 years showed a ventricular septal defect of the endocardial cushion type, patent ductus arteriosus, and pulmonary hypertension. At the age of 5 years 2 months, the patient underwent corrective open heart surgery. CYTOGENETIC
STUDIES
W i t h informed consent of the parents, cytogenetic studies were performed on peripheral blood lymphocyte cultures from the patient and her parents. Fibroblasts were also cultured from samples of the m y o c a r d i u m , lung, a n d skin of the anterior portion chest, obtained at the time of open h e a r t
82
Clinical and laboratory observations
surgery. The samples were minced into small pieces and then cultured in Eagle minimal essential medium supplemented with 15% fetal calf serum and antibiotics under an atmosphere of 5% carbon dioxide. Chromosome analysis was made at the second passage of the cultures. Chromosome preparations were subjected to GTG- and QFQbanding. In all tissues of the patient, two cell lines with 46,XX or 47,XX, +21 existed9 However, the ratio of trisomic cells varied from one tissue to another: 90.5% (38/42) in the myocardium, 72.7% (16/22) in the lung, 339 (10/30) in the skin, and 3.8% (9/233) in the peripheral blood lymphocytes. The trisomic cell line had three different chromosomes 21, with the short-arm morphology differing from each other on GTG- and QFQ-banding; the normal cell line had two different chromosomes 21. QFQ-banding analysis of polymorphisms on the short arm of chromosome 21 showed that the mosaicism in this patient resulted from mitotic nondisjunctionin the trisomic conceptus (Figure). The parental origin of the trisomy could not be determined; the parents had normal chromosomes. DISCUSSION This patient with mosaic trisomy 21 is interesting not only in that she had VSD of the endocardial cushion type, a malformation seldom associated with this type of chromosomal aberration, but also in that tissue-limited mosaicism was evident cytogenetically. Furthermore, study of the short-arm polymorphisms on chromosome 21 demonstrated that the mosaicism arose as a consequence of nondisjunction in the trisomic conceptus. In view of the fact that endocardial cushion defect (or VSD of the endocardial cushion type) and pulmonary hypertension are specifically associated with DS, 2 the occurrence of a cardiac defect in this patient may be related to the predominance of trisomy 21 in the heart and lung tissues. Recently the concept of tissue-specific mosaicism has attracted much attention. It is exemplified by studies on tetrasomy 12p mosaicism in the Pallister-Killian syndrome,3 mosaicism confined to villus cytotrophoblasts,4 and chromosome mosaicism in hypomelanosis of Ito. 5 Trisomy 4 or 16 mosaicism confined to skin fibroblasts has also been reported i n malformed live-born infants.6, 7 In this context, chromosome studies on various tissues are needed during the cytogenetic evaluation of patients with mental retardation and congenital multiple anomalies of an unclear cause. The difference in selection or tolerance in different tissues has been invoked to explain the occurrence of hssue-speclfiC mosaicism.8 The ratio of trisomic cells may decrease with
The Journal of Pediatrics July 1992
advancing age in peripheral blood lymphocytes of patients with mosaic DS. 9 In addition to endocardial cushion defect or VSD and pulmonary hypertension in trisomy 21, certain types of cardiovascular diseases have been reported to be specifically associated with certain types of chromosome abnormalities: coarctation of the aorta, bicuspid aortic valve, and hypoplastic left heart syndrome in monosomy X 2, 10; tetralogy of Fallot in dup(8q); total anomalous return of the pulmonary veins in pentasomy X; and patent ductus arteriosus in the cat-eye syndrome. 11 Although the cause of congenital heart disease is for the most part unknown, our observation suggests that localized mosaicism for a chromosome abnormality could be a cause of cardiac dysmorphogenesis. Particularly in patients with specific types of isolated cardiac malformation, cytogenetic study of a tissue specimen from the cardiovascular system appears to be warranted. REFERENCES
I. Stoll C, Alembik Y, Dott P, Roth MP. Epidemiologyof Down syndrome in 118,265 consecutive births. Am J Med Genet Suppl 1990;7:79-83. 2. Ferencz C, Neff CA, Boughman JA, Rubin JD, Brenner JI, Perry LW. Congenital cardiovascular malformations associated with chromosomeabnormalities: an epidemiologicstudy. J PEDIAT~1989;114:79-86. 39 Ward BE, Hayden MW, Robinson A. Isochromosome 12p mosaicism (Pallister-Killian syndrome): newborn diagnosis by direct bone marrow analysis. Am J Med Genet 1988;31: 835-99 4. Kalousek DK, Dill FJ, Pantzar T, MeGiUivrayBC, Yong SL, Wilson RD9 Confinedchorionic mosaicismin prenatal diagnosis. Hum Genet 1987;77:163-7. 5. Sybert VP, Pagon RA, Donlan M, Bradley CM. Pigmentary abnormalities and mosaicismfor chromosomal aberration: association with clinical features similar to hypomelanosisof Ito. J PEDIATR1990;116:581-6. 6. Marion JP, Fernhoff PM, Korotkin J, Priest JH. Pre- and postnatal diagnosis pf trisomy 4 mosaicism.Am J Med Genet 1990;37:362-5. 7. Gilbertson N J, Taylor JW, Kovar IZ. Mosaic trisomy 16 in a live newborn infant. Arch Dis Child 1990;65:388-9. 8. Hall JG. Somatic mosaicism: observations related to clinical genetics. Am J Hum Genet 1988;43:355-63. 9. Taylor AI. Further observationsof cell selection in vivoin normal/G trisomic mosaics. Nature 1970;227:163-4. 10. Larco RV, Jones KL, Benirschke K. Coarctation of the aorta in Turner syndrome:a pathologic study of fetuses with nuchal cystic hygromas, hydrops fetalis, and female genitalia. Pediatrics 1988;81:445-51. 11. Schinzel A. Catalogue of unbalanced chromosomeaberrations in man. Berlin, de Gruyter, 1984:853-4.