GBA1 and Parkinson disease: In Parkinson’s disease (PD), the most recent GWAS revealed 90 independent risk variants across 78 genomic loci.1 Although many single-nucleotide polymorphisms (SNPs) are in novel genomic loci, well-established PD genes discovered many years ago, such as LRRK2, PINK1, DJ-1, SNCA, GBA1, PRKN and MAPT still account for the vast majority of research on this disease.