title: Trisomy 15 mosaicism owing to familial reciprocal translocation t(1;15): implication for prenatal diagnosis.
abstract: We describe a 4-year-old female child with severe global mental retardation, myoclonic epilepsy, proximal hypotonia and dysmorphisms, whose prenatal diagnosis following amniocentesis revealed a constitutional female karyotype carrying a t(1;15)(q10;p11) familial reciprocal translocation. Post-natal high-resolution karyotype, Fluorescence in situ hybridization (FISH) screening for subtelomeric rearrangements, VNTR search for UPD15 in the blood and fibroblast, and WCP1 and 15 in the mother, failed to provide an explanation for the complex clinical phenotype of the proband. Since the pachytene configuration of the translocated chromosomes defines a high probability of 3:1 segregation, an extensive workup was undertaken to look for a possibly cryptic mosaicism. Four percent of the cells with trisomy 15 was found in the peripheral blood lymphocytes examined by classical cytogenetic technique and interphase FISH analysis. The clinical features associated with cryptic trisomy 15 mosaicism and the problems concerning prenatal diagnosis and genetic counselling for carriers of translocations at high risk of 3:1 segregation are discussed.
authors: University of Ferrara, Medical genetics Unit Via Fossato di Mortara, Italy. pprontera@hotmail.com
authors: Paolo
authors: P
authors: Prontera
authors: Barbara
authors: B
authors: Buldrini
authors: Vincenzo
authors: V
authors: Aiello
authors: Rita
authors: R
authors: Gruppioni
authors: Alessandra
authors: A
authors: Bonfatti
authors: Giovanna
authors: G
authors: Venti
authors: Alessandra
authors: A
authors: Ferlini
authors: Alberto
authors: A
authors: Sensi
authors: Elisa
authors: E
authors: Calzolari
authors: Emilio
authors: E
authors: Donti