Polymorphisms of the cholesterol-24S-hydroxylase (CYP46A1) and apolipoprotein E (APOE) genes are risk factors for Alzheimer's disease (AD). Plasma level of 24S-hydroxcholesterol (24-OHC), the metabolite of cholesterol, is thought to correlate with AD. The present study investigated the correlation between these genetic factors and blood 24-OHC and amyloid-beta (Aβ) levels in AD patients. Association analysis, logistic regression, and linear regression were used to analyze the correlation of CYP46A1 and APOE genotypes with blood 24-OHC and Aβ levels and AD risk. We found that the APOEε4 alleles were significantly higher in patients with AD and there was a potential synergistic interaction between the CYP46A1 C allele and APOEε4 allele in AD. Blood 24-OHC level and Aβ level were significantly higher in AD patients than controls, indicating 24-OHC could be a marker in AD diagnosis. However, AD patients with the CYP46A1 TT, but not CC, genotype had higher 24-OHC levels, which indicated that there may be other mechanisms in the relationship between CYP46A1 polymorphisms and AD.
Keywords: 24S-hydroxcholesterol (24-OHC); Alzheimer’s disease (AD); Amyloid-beta (Aβ); Apolipoprotein E (APOE); Cholesterol 24S-hydroxylase gene (CYP46A1).