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Balanced Translocation 46, XY, t(2;15)(q37.2;q11.2) Associated with Atypical Prader-Willi Syndrome

1997; Elsevier BV; Volume: 61; Issue: 2 Linguagem: Inglês

10.1086/514852

1537-6605

Jeffrey M. Conroy, Theresa A. Grebe, Laurie A. Becker, Karen D. Tsuchiya, Robert D. Nicholls, Karin Buiting, Bernhard Horsthemke, Suzanne B. Cassidy, Stuart Schwartz,

Genomic variations and chromosomal abnormalities

The lack of normally active paternal genes in 15q11-q13, as an outcome of either a paternal deletion or maternal disomy, accounts for >95% of all patients with Prader-Willi syndrome. Other mechanisms, including imprinting mutations and unbalanced translocations involving pat 15q11-q13, have been described elsewhere. In this study, we present a patient with a rare balanced, de novo translocation-46,XY,t(2;15)(q37.2;q11.2)-involving breakage within the Prader-Willi/Angelman syndrome region of the paternal homologue, without an apparent deletion. The patient demonstrated several manifestations of the Prader-Willi syndrome but was clinically atypical. Cytogenetic and molecular studies of this case demonstrated the translocation breakpoint to be between SNRPN and IPW, with mRNA expression of SNRPN and PAR-5 but absence of IPW and PAR-1 expression. These results suggest that disruption of either IPW expression or a nearby gene by an upstream break may contribute to the Prader-Willi syndrome phenotype and that expression of SNRPN or other upstream genes is responsible for other aspects of the classical Prader-Willi syndrome phenotype.