CLN5 and Parkinson disease: Based on the observed changes in BMP levels related to SNP mutations, the 90 PD-risk SNPs were categorized into four distinct classes: those whose mutations related to (1) increase or (2) decreased levels of the three BMPs, (3) had varying impacts across different cohorts and with different mutations, and (4) had no significant effect on urinary BMP levels in any cohort (Figure 2, data not shown for the fourth class).