| Literature DB >> 25464109 |
Alicia Semaka1, Chris Kay1, René D M Belfroid2, Emilia K Bijlsma2, Monique Losekoot2, Irene M van Langen3, Merel C van Maarle4, Mayke Oosterloo5, Michael R Hayden1, Martine J van Belzen6.
Abstract
New mutations for Huntington disease (HD) originate from CAG repeat expansion of intermediate alleles (27-35 CAG). Expansions of such alleles into the pathological range (≥ 36 CAG) have been exclusively observed in paternal transmission. We report the occurrence of a new mutation that defies the paternal expansion bias normally observed in HD. A maternal intermediate allele with 33 CAG repeats expanded in transmission to 48 CAG repeats causing a de novo case of HD in the family. Retrospectively, the mother presented with cognitive decline, but HD was never considered in the differential diagnosis. She was diagnosed with dementia and testing for HD was only performed after her daughter had been diagnosed. This observation of an intermediate allele expanding into the full penetrance HD range after maternal transmission has important implications for genetic counselling of females with intermediate repeats.Entities:
Keywords: HTT gene; Huntington disease; Intermediate allele; Maternal CAG repeat expansion; New mutation
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Year: 2014 PMID： 25464109 DOI： 10.1016/j.ejmg.2014.11.005
Source DB: PubMed Journal: Eur J Med Genet ISSN： 1769-7212 Impact factor: 2.708