HLA-DPB1 and Parkinson disease: In contrast, homologous NR_SVA_381 insertion (PP) (Table 6) significantly decreases the transcription levels of HLA-DPA1 (p=0.037) and HLA-DPB1 (p=0.001) in the PPMI cohort, and its presence as a homozygous genotype (PP) is a risk factor (Pc=0.012) for PD (Table 6A; Figure 4).