Currently, only a limited number of HSP types, such as SPG3A/ATL1, SPG7/PGN, SPG9/ALDH18A1, SPG18/ERLIN2, SPG30/KIF1A, SPG58/KIF1C, and SPG72/REEP2, have been demonstrated to exhibit both AD and AR patterns of inheritance. This evidence concerns the gene ERLIN2 and Alzheimer disease.