Thus, considering that presenilin and granulin are lysosomal proteins (Sannerud et al., 2016; Kao et al., 2017), it is logical to suggest that variants in the presenilin or granulin genes may exacerbate the cognitive impairments in PD by affecting lysosomal function and facilitating cell-to-cell transfer of proteopathic seeds in the progression of synucleinopathies. This evidence concerns the gene GRN and synucleinopathy.