To ensure ethnic homogeneity and exclude other genetic factors that may bias the assessment of the genetic contribution of GBA1 to PD in the Luxembourgish population, we excluded carriers of mutations in other PD-causing genes (point mutations: n = 10, nPD = 8,nHC = 2; CNV: nPD = 4) in PD-associated genes (no CNVs in GBA1 were detected), first-degree family members (n = 64, nPD = 8, npark = 2, nHC = 54), younger HC (<60 AAA) with first-degree relatives having PD (nHC = 74), and individuals of non-European descent (n = 6) from the cohort. Here, GBA1 is linked to Parkinson disease.