Prenatal diagnosis and molecular cytogenetic analysis of partial monosomy 10q (10q25.3→qter) and partial trisomy 18q (18q23→qter) in a fetus associated with cystic hygroma and ambiguous genitalia

Objectives To present the prenatal diagnosis and molecular cytogenetic analysis of a fetus with nuchal cystic hygroma and ambiguous genitalia. Case and Methods Amniocentesis was performed at 16 weeks' gestation because of the abnormal fetal sonographic finding of a large septated nuchal cystic hygroma. Genetic amniocentesis revealed a terminal deletion in the long arm of chromosome 10. The paternal karyotype was subsequently found to be 46,XY,t(10;18)(q25.3;q23). The maternal karyotype was normal. The pregnancy was terminated. A hydropic fetus was delivered with a septated nuchal cystic hygroma and ambiguous genitalia. Fluorescence in situ hybridization (FISH), microarray-based comparative genomic hybridization (CGH), and polymorphic DNA markers were used to investigate the involved chromosomal segments. Results FISH study showed absence of the 10q telomeric probe and presence of the 18q telomeric probe in the derivative chromosome 10. Microarray-based CGH analysis showed loss of distal 10q and gain of distal 18q. Polymorphic DNA marker analysis determined the breakpoints. The fetal karyotype was 46,XY,der(10)t(10;18)(q25.3;q23)pat. The chromosome aberration resulted in partial monosomy 10q (10q25.3 -> qter) and partial trisomy 18q (18q23 -> qter). Conclusions The present case provides evidence that partial monosomy 10q (10q25.3 -> qter) with partial trisomy 18q (18q23 -> qter) can be a genetic cause of fetal cystic hygroma and ambiguous genitalia. Cytogenetic analysis for prenatally detected structural abnormalities may detect unexpected inherited chromosome aberrations. Copyright (c) 2005 John Wiley & Sons, Ltd.