OMIM 603218 | DiseasesDB 33521 | |
Synonyms Huntington disease-like 1, HDL-1, HDL1, HD-like 1 | ||
The Huntington's disease-like syndromes (often abbreviated as HD-like or HDL syndromes) are a family of inherited neurodegenerative diseases that closely resemble Huntington's disease (HD) in that they typically produce a combination of chorea, cognitive decline or dementia and behavioural or psychiatric problems.
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HDL1
HDL1 is an unusual, autosomal dominant familial prion disease. Only described in one family, it is caused by an eight-octapeptide repeat insertion in the PRNP gene. More broadly, inherited prion diseases in general can mimic HD.
HDL2
HDL2 is the commonest HD-like syndrome and is caused by GTC/CAG triplet expansions in the JPH3 gene encoding junctophilin-3. GTC/CAG triplet expansions in the JPH3 gene encoding junctophilin-3. It is almost exclusively restricted to populations of African descent, and is actually more common than Huntington’s disease in black South Africans.
HDL3
HDL3 is a rare, autosomal recessive disorder linked to chromosome 4p15.3. It has only been reported in two families and the causative gene is unidentified.
Other causes of HD-like syndromes
Other neurogenetic disorders can cause an HD-like or HD phenocopy syndrome but are not solely defined as HDL syndromes. The commonest is spinocerebellar ataxia type 17 (SCA-17), occasionally called HDL-4. Others include mutations in C9orf72, spinocerebellar ataxias type 1 and 3, neuroacanthocytosis, dentatorubral-pallidoluysian atrophy (DRPLA), brain iron accumulation disorders, Wilson's disease, benign hereditary chorea, Friedreich's ataxia, mitochondrial disease.
A Huntington's disease-like presentation may also be caused by acquired causes.