PARKIN-coding polymorphisms are not associated with Parkinson's disease in a population from northeastern Mexico

Early- and late-onset Parkinson's disease (EOPD and LOPD) have been associated with mutations in the PARKIN gene. Several studies have reported association of Parkinson's disease (PD) with different polymorphisms in different ethnic populations. To study the role of PARKIN polymorphisms as risk factors for PD in a genetically homogeneous northeastern Mexican population, four previously described coding polymorphisms (Ser167Asn, Val380Leu, Arg366Trp, and Asp394Asn) were analyzed by using the PCR-RFLP technique. This case-control study comprised 117 unrelated patients (mean age 59+/-12 years, range 25-83 years) and 122 healthy unrelated control subjects (mean age 50+/-15 years, range 25-85 years). The homozygous Trp366 and Asn394 genotypes were not present in our study. The Ser167Asn and Val380Leu polymorphisms were not associated with this disease. For the control group, Ser167Asn and Val380Leu were in Hardy-Weinberg disequilibrium. Given that the main causes of Hardy-Weinberg disequilibrium in controls are selection bias or genotyping error, a competing risk of death associated with the mutant gene could be an explanation of this disequilibrium and lack of association.