Potential genetic biomarkers in the early diagnosisof Alzheimer disease: APOE and BIN1

Abstract

Alzheimer disease (AD) is triggered by interactions of multiple genetic and environmental factors. The APOE gene E4 allele is the best-known risk factor for AD, yet it represents a small ratio of genetic factors. According to genome-wide association studies, the BIN1 gene is the second important risk factor for AD, following the APOE gene. We aimed to identify a novel biomarker indicating susceptibility to AD by investigating APOE alleles and BIN1 gene polymorphisms in a Turkish population.Fifty-three AD patients and 56 controls were included to examine polymorphism and allele frequency of the APOE and BIN1 genes. Genomic DNAs were isolated from whole blood by SDS/proteinase K treatment, phenol-chloroform extraction, and ethanol precipitation. RFLP was done for identification of polymorphisms in the APOE gene and allele-specific PCR was used for the BIN1 gene.Frequency of the APOE E4 allele was higher in the AD patient group, while the frequency of the E2 allele was higher in controls. The E4/E4 genotype was detected in the AD patient group, while this genotype was not observed in the controls. The frequencies of BIN1 alleles were similar in both groups.There was a strong association between AD and the APOE E4 allele, while no such relation was observed with BIN1 gene polymorphism.