Maternal uniparental disomy for chromosome 14 by secondary nondisjunction of a initial trisomy
- Hopital Necker-Enfants Malades, Paris (France); and others
Three cases of maternal uniparental disomy for chromosome 14 (UD 14) have been described in the literature. In all three cases, the UD was found in carriers of Robertsonian translocations (13q14q or 14q and 14q). Here, we report on a new case of UD for chromosome 14 in a fetus in which the UD arose presumably by secondary nondisjunction of a trisomy 14. Prenatal diagnosis was performed on a 40-year-old woman by trans-abdominal chorionic villi sampling. Cytogenetic analysis showed a confined placental mosaicism (CPM) for trisomy 14 (100% of cells trisomic in short term preparations and 20% trisomic in cultured villi). The ultrasound examination was normal and after counselling the parents agreed to continue the pregnancy. Amniocentesis was performed and a normal 46,XX karyotype was found in the 70 cells examined. Molecular analysis of the parental origin of the fetus`s chromosome 14 was performed using microsatellite DNA markers evenly distributed on chromosome 14. Molecular results suggested a maternal heterodisomy. Another ultrasound examination was normal and after genetic counselling based on the small number of cases reported in the literature, the parents decided to keep the pregnancy. At birth, the clinical examination was normal. In conclusion, among the different mechanisms leading to UD, the correction of an initial trisomy by secondary nondisjunction might also be an important one. CPM is observed in about 2% of CVS studies and theoretically 1/3 of corrected trisomies could result in UD for the chromosomal pair that was originally trisomic. In order to provide adequate genetic counselling in these cases, it will be important to undergo molecular studies in the instances of confined placental mosaicism.
- OSTI ID:
- 134828
- Report Number(s):
- CONF-941009--
- Journal Information:
- American Journal of Human Genetics, Journal Name: American Journal of Human Genetics Journal Issue: Suppl.3 Vol. 55; ISSN AJHGAG; ISSN 0002-9297
- Country of Publication:
- United States
- Language:
- English
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