Interestingly, the sequence polymorphism at NPC1 residue 502 did not impair cholesterol clearance from lysosomes (Figure 3), and none of the residues under positive selection were found to be mutated in Niemann-Pick type C disease patients (Runz et al., 2008; Vanier and Millat, 2003). This evidence concerns the gene NPC1 and Niemann-Pick disease type C.