MAPT and Parkinson disease: In heterozygous NPC1‐mutant mice, a significant loss of Purkinje cells and increase in brain cholesterol and hyperphosphorylated tau have been detected in the central nervous system.17 Parallelly, several case reports have described parkinsonism and Lewy body neuropathology in heterozygous NPC1 carriers.19, 20, 21, 33