Investigation of five polymorphic DNA markers associated with late onset Alzheimer disease

Abstract

Alzheimer's disease is a complex neurodegenerative disorder characterized by memory and cognitive impairment and is the leading cause of dementia in the elderly. The aim of our study was to examine the polymorphic DNA markers CCR2 (+190 G/A), CCR5δ32, TNF-α (-308 G/A), TNF-α (-863 C/A) and CALHM1 (+394 C/T) to determine the relationship between these polymorphisms and the risk of late onset Alzheimer's disease in the population of Eastern Azerbaijan of Iran. A total of 160 patient samples and 163 healthy controls were genotyped by PCR-RFLP and the results confirmed using bidirectional sequencing. Statistical analysis of obtained data revealed non-significant difference between frequency of CCR5δ32 in case and control groups. The same result was observed for TNF-α (-863 C/A) genotype and allele frequencies. Contrary to above results, significant differences were detected in frequency of TNF-α (-308 G/A) and CCR2-64I genotypes between the cases and healthy controls. A weak significant difference observed between allele and genotype frequencies of rs2986017 in CALHM1 (+394 C/T; P86L) in patient and control samples. It can be concluded that the T allele of P86L variant in CALHM1 & +190 G/A allele of CCR2 have a protective role against abnormal clinical features of Alzheimer's disease.