Mitochondrial Complex I Gene VariantAssociated With Early Age at Onsetin Spinocerebellar Ataxia Type 2

A common mitochondrial complex I genepolymorphism (10398G) is reported to be inversely associatedwith the risk of Parkinson disease. We hypothesizedthat this variant might have a protective effect onthe central nervous system and therefore might delay theonset of symptoms in spinocerebellar ataxia type 2(SCA2)...(AU)

Mitochondrial complex I gene variant associated with early age at onset in spinocerebellar ataxia type 2.

BACKGROUND: A common mitochondrial complex I gene polymorphism (10398G) is reported to be inversely associated with the risk of Parkinson disease. We hypothesized that this variant might have a protective effect on the central nervous system and therefore might delay the onset of symptoms in spinocerebellar ataxia type 2 (SCA2). OBJECTIVE: To assess the association of the 10398G polymorphism with age at onset in Cuban patients with SCA2. DESIGN: Genetic association study. SETTING: Holguin, Cuba. PATIENTS: Forty-six Cuban patients with SCA2. MAIN OUTCOME MEASURES: Presence or absence of the 10398G polymorphism was determined in 46 Cuban patients with SCA2 and early or late onset of symptoms, defined as at least 2 SDs lower than or higher than the mean age at onset for patients with a similarly sized triplet repeat expansion. RESULTS: The polymorphism was present in 11 of 27 Cuban patients with SCA2 and early onset (41%) vs 2 of 19 with late onset (11%) (Fisher exact test; P = .04). CONCLUSION: Contrary to our prediction of a later onset of SCA2 in patients with the 10398G polymorphism, we find that this variant is associated with an earlier age at onset in Cuban patients with SCA2.