An infant with trisomy 9 mosaicism presenting as a complete trisomy 9 by amniocentesis

Abstract

We present a case in which amniocentesis performed at 33 weeks' gestation because of symmetrical intrauterine growth retardation and decreased amniotic fluid volume led to the prenatal diagnosis of a fetus with a karyotype of 47,XX,+9,t(1;20)(q42;p11.2) pat, i.e., with an extra chromosome 9 and a balanced translocation between chromosomes 1 and 20. At delivery, the baby showed clinical features of trisomy 9, yet chromosome analysis of the cord blood revealed no trisomy 9 cells, a finding confirmed by neonatal blood karyotyping. The balanced translocation was present in all cells. A skin biopsy confirmed trisomy 9 mosaicism with 10 per cent trisomy 9 cells. The baby died at 6 weeks and an autopsy was obtained. Chromosome analysis of different organs demonstrated different frequencies of the mosaicism of trisomy 9. The possible underlying mechanism for the discrepancy between the karyotype results by amniocentesis and those of other tissues is discussed.

Trisomy 9: Review and report of two new cases

“…We reviewed reports of 36 cases of mosaic and nonmosaic trisomy 9 which resulted in a live birth or term stillbirth, in addition to our 2 previously unreported cases [Akatsuka et al, 1979;Anneren and Sedin, 1981;Bowen et al, 1974;Carpenter and Tomkins, 1982;Delicado et al, 1985;de Michelina et al, 1992;Diaz-Mares et al, 1990;Feingold and Atkins, 1973;Frydman et al, 1981;Ginsberg et al, 1989;Haslam et al, 1973;Herranz et al, 1987;Kaminker et al, 1985;Katayama et al, 1980;Kurnick et al, 1974;Levy et al, 1989;Lewandowski and Yunis, 1977;Mace et al, 1978;Mantagos et al, 1981;Marino et al, 1989;Pfeiffer and Muller, 1984;Qazi et al, 1977;Romain and Sullivan, 1983;Sanchez et al, 1982;Schinzel et al, 1974;Seabright et al, 1976;Sherer et al, 1992;Sutherland et al, 1976;Taslimi and Glass, 1990;Tropp and Currie, 1977;Wilroy et al, 1985;Wilson and Barr, 1983;Williams et al, 19851. Four prenatally diagnosed cases which did not result in term birth were also reviewed and will be discussed, but were not included in the data analysis [Franke et al, 1975;Frohlich, 1982;Schwartz et al, 1989;Zadeh et al, 19871.…”

“…The variability in outcome among the mosaic cases may depend on differences in the origin of the nondisjunction, and on whether the maternal or paternal cell line chromosome has been lost in the euploid cell line, in the timing of the loss of the trisomic cell line, or in timing of a postzygotic nondisjunction. The cases of Sherer et al [1992] and Schwartz et al [1989] illustrate that confined placental mosaicism may represent previous fetal trisomy; further studies are indicated to determine if the presence of fetal uniparental disomy in these cases is associated with specific fetal abnormalities. In the 3 cases in which maternal origin could be determined by heterochromatic variations of chromosome 9, the heterochromatic chromosome was present only once in the euploid cell line, with marked variability in outcome of the affected infants.…”

“…Schwartz et al [1989] reported a case of mosaic trisomy 9 diagnosed by amniocentesis in which 46% of amniocytes, but only 1 of 50 fetal lymphocytes, were trisomic. In the case of Sherer et al [1992], trisomy 9 was identified by amniocentesis in all cells from all colonies and cultures, but no trisomy 9 cells were found in newborn cord or peripheral blood. Skin fibroblasts showed trisomy 9 in 10% of cells, and the child had the characteristic phenotype of trisomy 9.…”

“…0 1995 Wiley-Liss, Inc. Haslam et al, 1973;Herranz et al, 1987;Kaminker et al, 1985;Katayama et al, 1980;Kurnick et al, 1974;Levy et al, 1989;Lewandowski and Yunis, 1977;Mace et al, 1978;Mantagos et al, 1981;Marino et al, 1989;Pfeiffer and Muller, 1984;Qazi et al, 1977;Romain and Sullivan, 1983;Sanchez et al, 1982;Schinzel et al, 1974;Schwartz et al, 1989;Seabright et al, 1976;Sherer et al, 1992;Sutherland et al, 1976;Taslimi and Glass, 1990;Tropp and Currie, 1977;Wilroy et al, 1985;Wilson and Barr, 1983;Williams et al, 1985;Zadeh et al, 1987).…”

Prenatal Diagnosis of Nonmosaic Trisomy 9 in a Fetus with Severe Renal Disease

“…Saura et al [14] reported a case in which chorionic villus sampling and amniocentesis revealed a nonmosaic trisomy 9 but postmortem tissue samples demonstrated no abnormal cell lines in the placenta, amnion, or skin, although a 60% mosaicism in the colon and 100% trisomy 9 cells in the lungs were found. Sherer et al [16] reported a similar case, in which nonmosaic trisomy 9 was identified by amniocentesis at 31 weeks of gestation but no trisomy 9 cell lines were found in either the neonatal umbilical cord or neonatal peripheral blood, although skin fibroblasts showed trisomy 9 in 10% of cells. Recently, fluorescence in situ hybridization has been used to demonstrate low-grade mosaicism in a case in which conventional cytogenetic techniques had shown nonmosaic trisomy 9 in neonatal peripheral blood [7].…”