Assessment of a DJ-1 (PARK7) polymorphism in Finnish PD

To the Editor: We read with interest the report by Eerola et al.1 that demonstrates lack of association between a DJ-1 promoter polymorphism and Parkinson disease (PD). The authors also claim that their “observations indicate strong linkage disequilibrium (LD) across the gene” and that they provide “compelling evidence that common variation within DJ-1 does not act as a risk factor for PD.” However, their evidence represents an oversimplification of LD architecture and its potential in common trait mapping. …