Inheritance: autosomal dominant, with one or both parents affected. Many patients have South African ancestry.
Chromosome location: 16q24.3
Gene affected: JPH3 (Junctophilin-3)
Clinical features:
(1) onset during adulthood, ranging from young to late in life
(2) abnormal movements (Parkinsonism, dysarthria, hyperreflexia, tremor, chorea, incoordination, etc)
(3) emotional disorder (depression, apathy, irritability. psychosis, etc)
(4) cognitive impairment progressing to dementia
(5) weight loss despite adequate food intake
(6) progressive with death within 10+ years
(7) complications may arise from repeated falls or from aspiration
Imaging studies show atrophy of the caudate and cerebral cortex.
Laboratory findings:
(1) variable erythrocytes with acanthocytosis
(2) >= 41 CTG repeats at JPH3
(3) normal HTT gene (exclusion of Hungtington's disease)
