Besides GBA1, other (genetic) factors are also known as predictors of cognitive deterioration in Parkinson’s disease, such as variants in the apolipoprotein E, microtubule-associated protein tau and α-synuclein loci.58-60 Some of the non-GBA-PD might be secondary to other lysosomal defects. The gene discussed is APOE; the disease is Parkinson disease.