Adult-onset huntington disease phenocopies

Huntington´s disease (HD) is a well-defined autosomal dominant neurodegenerative disease. It is caused by CAG repeat expansions in huntingtin

gene. There are a significant number of HD cases where this mutation was not found and such cases are named HD-like phenotype

(HDL) or HD phenocopies. The aim of our work is to review these HDL. We studied existing resources and further we describe these syndromes,

including HDL1, HDL2, and HDL4 (SCA17), and also (because of phenotypic overlap) dentatorubral-pallidoluysian atrophy, Friedreich‘s ataxia,

neuroferritinopathy and neuroacanthocytosis.We also bring our proposal for diagnostic process, to diagnose the most frequent syndromes.

However, current worldwide research shows, that major number of patients with HDL phenotype remain without final diagnosis. This suggests

that other genes or gene modifiers may exist, where the mutation can cause the syndrome with clinical features similar to HD.

Keywords: Huntington´s disease, phenocopy, huntingtin, CAG triplet, dentato-rubro-pallido-luysian atrophy, spinocerebellar atrophy, Huntington´s disease like, neuroacanthocytosis, benign hereditary chorea.