To avoid the possible confounding effect of population stratification, we employed a discordant sibling study design and a liberalization of the sibling transmission disequilibrium test to confirm the association of the S18Y variant of the ubiquitin carboxi-terminal hydrolase L1 (UCHL1) gene with Parkinson's disease (PD). The study included 497 case-control pairs (427 case-unaffected sibling pairs and 70 case-unrelated control pairs). Analyses confirmed a significant inverse association of the UCHL1 S18Y polymorphism with PD overall (OR = 0.18, 95% CI = 0.05-0.64, p = 0.002, recessive model) and in several strata.
- Association study
- Parkinson's disease
- Transmission disequilibrium test
- Ubiquitin proteasomal system
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