ITSN1 and Parkinson disease: Here, in analyzing whole-genome sequence data from 3,809 PD cases and 247,101 controls in the UK Biobank, we discover that protein-truncating variants in ITSN1 confer a substantially increased risk of PD (p = 6.1 × 10−7; odds ratio [95% confidence interval] = 10.5 [5.2, 21.3]).