AD represents 90% of ND cases, and the chances of it developing increase with changes in the 15 indicated genes predisposing to ND (NDG): GBA1, APP, PSEN1, MAPT, GRN, SETX, SPAST, CSF1R, C9orf72 [67], TET2 [68], TBK1 [69], TOMM40, APOC1 [70], APOE [70,71] and TREM2 [72,73,74,75,76,77,78]. Here, TREM2 is linked to Norrie disease.