GBA1 and synucleinopathy: 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.