Mitochondrial complex I gene variant associated with early age at onset in spinocerebellar ataxia type 2
David K Simon1, Kangni Zheng, Luis Velázquez
1Department of Neurology, Beth Israel Deaconess Medical Center, 77 Avenue Louis Pasteur, Room HIM-847, Boston, MA 02115, USA. dsimon1@bidmc.harvard.edu
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.
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