However, genetic observations such as reduced PD penetrance5 of GBA1 variants in familial cases, the occurrence of phenocopies in GBA-PD families3,4, and comparable age‐specific PD risk in homo-and heterozygous GBA1 variant carriers39 indicate that GBA1 variants alone do not cause alpha synucleinopathy or PD in the heterozygous GBA1 variant carriers. This evidence concerns the gene GBA1 and Parkinson disease.