InterPro: IPR006155 Machado-Joseph disease protein MJD

Human genes containing triplet repeats can markedly expand in length, leading to neuropsychiatric disease. Expansion of triplet repeats explains the phenomenon of anticipation, i.e. the increasing severity or earlier age of onset in successive generations in a pedigree [1]. A novel gene containing CAG repeats has been identified and mapped to chromosome 14q32.1, the genetic locus for Machado-Joseph disease (MJD). Normally, the gene contains 13-36 CAG repeats, but most clinically diagnosed patients and all affected members of a family with the clinical and pathological diagnosis of MJD show expansion of the repeat number, from 68-79 [2]. Similar abnormalities in related genes may give rise to diseases similar to MJD. MJD is a neurodegenerative disorder characterised by cerebellar ataxia, pyramidal and extra-pyramidal signs, peripheral nerve palsy, external ophtalmoplegia, facial and lingual fasciculation and bulging. The disease is autosomal dominant, with late onset of symptoms, generally after the fourth decade.