KTN1 and Parkinson disease: As observed in the current study, the major alleles G of rs8017172, T of rs17253792, and C of rs945270 in the H2 block, the three among the only four known GMV-associated alleles at KTN1 (Hibar et al., 2015; Chen et al., 2017; Xu et al., 2017), significantly increased risk for PD, KTN1 mRNA expression levels in the putamen, and the putamen GMVs.