BCKDK and Parkinson disease: BCKDK/STX1B (branched chain ketoacid dehydrogenase kinase/syntaxin 1B) locus was established as a PD risk factor in GWAS meta-analysis by Nalls et al. Only one SNP (rs14235) is known to be associated with PD, thus replication studies are needed to confirm the actual association (Nalls et al., 2014).