SMPD1 and Parkinson disease: A recent study that assessed the association of specific founder mutations in each of the lysosomal storage disorder genes HEXA, SMPD1 and MCOLN1, in 938 Ashkenazi Jewish (AJ) PD patients and 282 matched AJ controls, reported SMPD1 L302P as a risk factor for PD in the AJ population[12].