Spinocerebellar ataxia type 22 (SCA22) is a very rare subtype of type I autosomal dominant cerebellar ataxia (ADCA type I; see this term). It is characterized by slowly progressive cerebellar ataxia and hyporeflexia.
Prevalence is unknown. Only 9 cases in a 4-generation Chinese Han family have been reported to date.
Symptomatic disease onset of SCA22 is 35 to 46 years and features overlap significantly with SCA19 (see this term). SCA19 however has a wider age range of 10 to 46 years. Clinical features usually include only cerebellar signs. Occasionally hyporeflexia is present.
Linkage to chromosome 1p21-q23 has been suggested but it is also hypothesized that SCA19 and SCA22 share the same genetic locus.
There is insufficient clinical data to draw conclusions concerning prognosis.
Last update: May 2011
- Dr Shinsuke FUJIOKA
- Dr N WHALEY
- Dr Zbigniew WSZOLEK