The association of Alzheimer’s disease-related SNPs with mild cognitive impairment susceptibility in the Chinese population

Previous Genome-wide association studies have identified several single nucleotide polymorphisms (SNPs) associated with Alzheimer's disease (AD), whereas their associations with mild cognitive impairment (MCI) remain unclear. To evaluate the associations between 100 representative AD-associated SNPs and susceptibility to MCI in the Chinese population. We recruited 200 MCI patients and 200 cognitively-healthy controls from the community, matched for age and sex. Associations between SNPs and MCI risk were estimated using lasso regression, adjusted for APOE status, using different genetic models. Fifteen SNPs in nine genes (including CLU, SORL1, PICALM, BDNF, NOS3, MTHFR, TOMM40, BIN1, and PVRL2) were associated with MCI in single-SNP analysis. In the multi-SNP association test, rs1801133 and rs9331888 of CLU were consistently associated with MCI risk in the dominant model. TOMM40 rs2075650 (G) was associated with MCI risk in the dominant model by age and education (OR = 2.41, 95%CI = 1.27-4.59), but disappeared when further adjusted for APOEε4 status. PICALM rs561655 (G) (OR = 0.52, 95%CI = 0.30-0.92) and NOS3 rs1549758 (T) (OR = 0.53, 95%CI = 0.30-0.94) were identified as protective genetic factors of MCI for the first time in dominant model combined with the APOEε4 allele. Moreover, MTHFR rs1801133 (A) and CLU rs9331888 (G) showed more susceptibility to MCI in the additive model. SORL1 rs641120(G) showed a protective effect, whereas BIN1 rs5733839 consistently showed a risk effect for MCI in the overdominant model, regardless of APOEε4 status. This study suggests that some AD-associated SNPs are associated with cognitive decline and may have important implications for future studies.