CYP1A1 and Parkinson disease: In context of PD, the C allele of rs12441817 (CYP1A1) was shown to be associated with reduced risk of PD (P = 5.22 × 10–5, OR = 0.87, 95% CI = 0.81–0.93) in a European-descent based GWAS (Nalls et al., 2014).