A case of maternal uniparental disomy of chromosome 9 diagnosed prenatally and the related problem of residual trisomy.
HR Slater, A Ralph, A Daniel, S Worthington, C Roberts
Prenat Diagn | Published : 2000
Non-mosaic trisomy 9 was found in a chorionic villus (CV) sample taken from a 43-year-old woman referred for prenatal chromosome analysis due to advanced maternal age. Follow-up amniocentesis revealed level 2 mosaicism for trisomy 9. Trisomy 9 was not detected at fetal blood sampling. Molecular analysis of fetal (amniocyte) DNA showed maternal uniparental heterodisomy (UPD) for chromosome 9. Two crossovers resulted in a region of isodisomy in the distal long arm. Trisomy rescue of a meiosis 1 segregation error seems to have been responsible for the uniparental disomy of chromosome 9. The pregnancy continued and neonatal blood testing showed a mosaic trisomy 9 karyotype, i.e. 4/50 cells analy..View full abstract