Gene Expression and Methylation Analysis of ABCA7 in Patients with Alzheimer's Disease

Background/Objective: The aim of this study was to examine the blood gene expression and methylation of ATP-binding cassette sub-family A member 7 gene (ABCA7) as a biological marker of AD. Methods: AD subjects (n = 50; 11 males, 77.7 +/- 6.05 years old) and age-and sex-matched healthy controls (n = 50) were recruited. A single nucleotide polymorphism in ABCA7 (rs3764650), methylation rates of CpG sites in the ABCA7 promoter region, and ABCA7 mRNA expression levels in peripheral blood were examined. Results: The distribution of the rs3764650 polymorphism in AD subjects was not different from that of controls. Although the methylation rates of AD subjects were not significantly different from those of controls, the ABCA7 mRNA expression level in AD subjects was significantly higher than that in controls. Additionally, the ABCA7 mRNA expression level in AD subjects was significantly correlated with Mini-Mental State Examination recall, the Alzheimer's Disease Assessment Scale total score, and the Clinical Dementia Rating score. We also found a significant correlation between the ABCA7 mRNA expression level and duration of illness. Conclusion: The ABCA7 mRNA expression level in peripheral blood may be a marker for early stages of AD and disease progression regardless of rs3764650 and the methylation rate of its promoter.