GBA1 and dementia: Finally, our stratification of dementia risk only included the MAPT haplotype as a genetic risk factor, although recent studies have suggested that mutations in the gene GBA encoding glucocerebrosidase are the numerically greatest dementia risk contributors.65 We have a posteriori genotyped our participants and found that the all GBA mutation carriers (n = 5) in this PD cohort, aside from one, were classified as high dementia risk by our stratification method.