Gene mutations in a Han Chinese Alzheimer's disease cohort

Objective: Alzheimer's disease (AD) is the most common form of dementia characterized by memory loss at disease onset. The gene mutations in the amyloid precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2) are the frequent causes of AD. However, the clinical and genetic features of AD overlap with other neurodegenerative diseases. The present study aimed to identify the clinical and genetic characteristics in a Han Chinese AD cohort. Methods: Detailed clinical assessment was applied to all the patients. We screened amyloid precursor protein (APP), PSEN1, PSEN2, and microtubule-associated protein tau (MAPT) genes were assessed in 83 sporadic AD patients by Sanger sequencing. A total of 25 probands from families with AD were subjected to next-generation sequencing on 53 dementia-associated genes to capture the target region, and Sanger sequencing was used to detect the variants in the DNA sequence. Results: PSEN1 p.L226R was found in an early-onset AD (EOAD) family characterized by language impairment at disease onset, a novel probably pathogenetic variant (p.D534H) was identified in a frontal-temporal dementia gene, TANK-binding kinase 1 (TBK1) with a typical AD phenotype in a late-onset AD (LOAD) family, and a PSEN2 p.H169N mutation and two benign MAPT (p.Q230R and p.V48L) mutations were detected in three EOAD patients. Conclusions: Thus, five variants were identified in a Han Chinese cohort. In the present study, a novel, probably damaging FTLD gene TBK1variant with a typical AD phenotype was detected. Also, the phenotypic characteristics of PSEN1 p.L226R, a PSEN2 pathogenic mutation, and two likely benign MAPT variants were described. Hence, screening for mutations in other dementia genes could be further explored in clinically diagnosed AD patients.