Intronic CYP46 polymorphism along with ApoE genotype in sporadic Alzheimer Disease: from risk factors to disease modulators

Increasing biological and clinical findings argue for a link between brain cholesterol turnover and Alzheimer Disease (AD), high cerebral levels of the former increasing Abeta load. Cerebral cholesterol elimination involves two mechanisms dependent on Apolipoprotein E (ApoE) and cholesterol 24-hydroxylase (CYP46). The aim of this study was to evaluate an intronic variation in CYP46 (intron 2, T --> C) along with ApoE genotype as risk factors for AD and to establish the correlation between CYP46/ApoE polymorphism and disease progression. One-hundred and fifty-seven AD patients, who had been followed periodically through 1-year follow-up after enrolment, and 134 age- and gender-matched controls entered the study. The distribution of CYP46 genotypes was significantly different in AD compared to controls (P < 0.004), being CYP*C allele higher in AD patients (P < 0.002). AroE epsilon4 genotype was more frequent in AD (41.4%) than in controls (15.9%, P < 0.0001). The odds ratio (OR) for AD risk in CYP46*C carriers was 2.8, and in ApoE epsilon4 carriers was 4.05; the OR for having both CYP46*C and ApoE epsilon4 was 17.75, demonstrating the their synergic effect on AD risk. In AD patients, CYP46*C along with ApoE epsilon4 genotype were associated with a higher cognitive decline at 1-year follow-up (P < 0.02). These findings provide direct evidence that CYP46 and ApoE polymorphisms synergically increase the risk for AD development, and influence on the rate of cognitive decline. (C) 2003 Elsevier Inc. All rights reserved.