Trisomy 15 mosaicism owing to familial reciprocal translocation t(1;15): implication for prenatal diagnosis |
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Authors: | Paolo Prontera Barbara Buldrini Vincenzo Aiello Rita Gruppioni Alessandra Bonfatti Giovanna Venti Alessandra Ferlini Alberto Sensi Elisa Calzolari Emilio Donti |
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Affiliation: | 1. University of Ferrara, Medical genetics Unit Via Fossato di Mortara, 74 44100 Ferrara, Italy;2. University of Perugia, Medical Genetics Service, Department of Clinical and Experimental Medicine, 06100, Perugia, Italy. |
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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. Copyright © 2006 John Wiley & Sons, Ltd. |
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Keywords: | trisomy 15 mosaicism familial reciprocal translocation prenatal diagnosis 3:1 segregation |
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