Especially the genotype–phenotype relationship of GBA1 carriers in PD is of great interest in the field: Whilst overall more severe motor and non-motor symptoms are seen in GBA1 variant carriers15–17, pathogenic variants resulting from recombinant alleles cause Gaucher’s disease (GD), and risk variants are not necessarily associated with GD but increase the risk of developing PD18. This evidence concerns the gene GBA1 and Parkinson disease.