Mutation profile of APP, PSEN1, and PSEN2 in Chinese familial Alzheimer's disease.

Causative mutations in the genes encoding amyloid precursor protein (APP), presenilin 1 (PSEN1), or presenilin 2 (PSEN2) account for a majority of cases of familial Alzheimer disease (FAD) inherited in an autosomal-dominant pattern. For the sake of characterizing mutations, index patients from 148 families with FAD were enrolled from mainland China. Sanger sequencing of the genes APP, PSEN1, and PSEN2 was performed to characterize the mutation spectrum of the Chinese population. Thirteen of 148 (8.8%) individuals had possible pathogenic APP, PSEN1, or PSEN2 variants, including 2 (15.4%) APP variants, 8 (61.5%) PSEN1 variants, and 3 (23.1%) PSEN2 variants. PSEN1 variants represented the largest proportion in Chinese FAD, and PSEN2 variants are responsible for late-onset FAD in China. Analysis of genetic-clinical correlations permitted the conclusion that FAD phenotypes were mainly influenced by specific genetic defects.