Olivopontocerebellar atrophy

>OPCA I (or SPA 1) -- Autosomal dominant.

Onset of symptoms usually in the third or fourth decade of life, most often around age 30. Due to expansion of a CAG trinucleotide sequence in the ataxin-1 gene (ATX1) on chromosome 6p23. >OPCA II -- Autosomal recessive.

Called the Fickler-Winkler type of OPCA.

Differs from OPCA I in a lack of involuntary movements and of sensory changes.

Gene not known.

>OPCA II (or SCA 2) -- Autosomal dominant.

Called the Cuban type of OPCA.

Due to expansion of a CAG trinucleotide sequence in the ataxin-2 gene (ATX2) on chromosome 12q24. >OPCA III (or SCA 7) -- Autosomal dominant.

OPCA with macular degeneration and ophthalmoplegia.

Due to expansion of a trinucleotide sequence in the ataxin-7 gene (SCA7) on chromosome 3p.

>OPCA IV -- Autosomal dominant.

Similar clinically to OPCAI but with spastic paraplegia.

May be due to a different mutation in the ataxin-1 gene (ATX1) and so be alleleic to OPCA I.

>OPCA V -- Autosomal dominant.

OPCA with progressive dementia and extrapyramidal neurologic signs.

The gene responsible for this disease has not been identified.

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