| A severe neurodegenerative disorder considered part of the neuroacanthocytosis syndromes with a triad of movement, psychiatric and cognitive abnormalities. Prevalence and incidence are unknown but this disease is very rare, with fewer than 50 families reported worldwide. Patients may develop psychiatric abnormalities as the initial manifestation, with later appearance of chorea, parkinsonism and dystonia. The disease may evolve from chorea to a more bradykinetic, dystonic phenotype, or remain parkinsonian. Caused by expanded trinucleotide repeats of the JPH3 junctophilin 3 gene (16q24.3). Affected individuals have CTG/CAG repeat expansions of 41-59 triplets (normal population: 6-27). Follows an autosomal dominant pattern of inheritance. A relentlessly progressive disorder with a poor prognosis. |
