Using data from the National Institutes of Neurological disease and Stroke's (NINDS) study of Parkinson disease (PD), we recently reported that single nucleotide polymorphisms (SNPs) in a region containing the Calpastatin (CAST) gene were associated with PD. Here we follow up this finding with an analysis of the Center for Inherited Disease Research's (CIDR) genome-wide association study in familial PD. After adjusting for population stratification and multiple testing, we find a significant association (P = 0.0167) between PD and SNP rs1559085 in CAST. These findings confirm CAST/PD associations in a second, independent, dataset and suggest that CAST be prioritized for further investigation.