Tetrasomy 18p de novo: parental origin and different mechanisms of formation.

摘要: We have used eight PCR-based DNA polymorphisms to determine the parental origin and mechanisms of formation in 9 patients with de novo nonmosaic tetrasomy 18p. The patients, 4 girls 5 boys, had clinical features characteristic i(18p) syndrome. supernumerary marker chromosome was identified by fluorescence situ hybridization (FISH) analysis using centromeric probes a flow-sorted 18p-specific library. isochromosome maternal all cases. 18p cannot be explained single model. In 6 cases, meiosis II nondisjunction, followed subsequent postzygotic misdivsion, 1 case nondisjunction misdivision were most likely formation. Alternative are suggested remaining 2