TPCN1 and Parkinson disease: While TPC1 is widely expressed throughout the endolysosomal pathway, TPC2 is preferentially expressed in the late endosome/lysosome (Brailoiu et al., 2009; Calcraft et al., 2009); TPC2 has been shown to be associated with Parkinson’s disease (Hockey et al., 2015) and blood vessel formation (Favia et al., 2014); TPC2-knockout mice are highly susceptible to non-alcoholic fatty liver hepatitis, the role of TPC1, however, remains unclear (Grimm et al., 2014).