Double aneuploidy with Edwards–Klinefelter syndromes (48,XXY,+18) of maternal origin: Prenatal diagnosis and molecular cytogenetic characterization in a fetus with arthrogryposis of the left wrist and aplasia of the left thumb

Abstract

Objective To present the prenatal diagnosis and molecular investigation of the parental origin and mechanism of nondisjunction underlying an 48,XXY,+18 karyotype in a fetus with congenital abnormalities, and to review the literature. Materials, Methods, and Results A 42-year-old woman was referred for amniocentesis at 18 weeks of gestation because of advanced maternal age. Prenatal ultrasound revealed bilateral choroid plexus cysts. Amniocentesis revealed a karyotype of 48,XXY,+18. The parental karyotypes were normal. Level II ultrasound revealed a flexion contracture deformity of the left wrist with absence of the thumb. The pregnancy was terminated at 22 weeks of gestation. A 332 g male fetus was delivered with clenched hands, arthrogryposis of the left wrist, aplasia of the left thumb, micrognathia, low-set ears, hypertelorism, rocker-bottom feet, and a normal penis. Quantitative fluorescent polymerase chain reaction assays using polymorphic DNA markers showed a triallelic pattern with a dosage ratio of 1:1:1 (paternal:maternal:maternal) for chromosome 18-specific markers, and a monoallelic pattern of a single maternal allele for chromosome X-specific markers. The fetus inherited two copies of two different maternal alleles on chromosome 18, and two copies of a single maternal allele on chromosome X. The molecular result, along with the karyotype of 48,XXY,+18, was consistent with the occurrence of nondisjunction of chromosome 18 in a maternal meiosis I error and nondisjunction of chromosome X in a maternal meiosis II error or less likely a postzygotic mitotic error. Conclusion The present case provides evidence that abnormal separation of chromosomes 18 and X resulting in double aneuploidy may occur in different cell divisions, and such an occurrence is related to advanced maternal age.