BREAKAGE IN THE SNRPN LOCUS IN A BALANCED 46,XY,T(15-19) PRADER-WILLI-SYNDROME PATIENT

A patient with Prader-Willi syndrome (PWS) was found to carry a de nov o balanced reciprocal translocation, t(15;19)(q12;q13.41), which disru pted the small nuclear ribonucleoprotein N (SNRPN) locus. The transloc ation chromosome 15 was found to be paternal in origin, Uniparental di somy and abnormal DNA methylation were ruled out, The translocation br eakpoint was found to have occurred between exon 0 (second exon) and 1 (third exon) of the SNRPN locus outside of the SmN open reading frame (ORF), which is intact. The transcriptional activities of ZNF127, IPW , PAR-1, and PAR-5 were detected with RT-PCR from fibroblasts of the p atient, suggesting that these genes may not play a significant role in the PWS phenotype in this patient. Transcription from the first two e xons and last seven exons of the SNRPN gene was also detected with RT- PCR; however, the complete mRNA (10 exons) was not detected, Thus, the PWS phenotype in the patient is likely to be the result of disruption of the SNRPN locus.