Association between Polymorphism in XRCC7 Gene (G6721T) and Risk of Multiple Sclerosis: A Case-control Study

The XRCC7 gene, encoding the catalytic subunit of DNA-activated protein kinase (DNA-PKcs), is one of the most important genes in the DNA double-strand break (DSBs) repair. It is supposed that DNA repair gene malfunction is the main risk factor in various neurodegenerative diseases. The impact of XRCC7 G6721T (rs7003908) polymorphism on the splicing regulation cause mRNA instability. Therefore, the current study aimed to assess the possible association between XRCC7 G6721T polymorphism and MS susceptibility in a sample of Iranian population.

This case-control study was performed on 113 MS patients versus 122 healthy controls. The genotype analysis of the XRCC7 G6721T polymorphism was performed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique.

A significant statistical difference in the genotypic frequencies of TT between cases and controls was found (P=0.003). The genotypic frequencies of the XRCC7 G6721T polymorphism were not significantly different in MS patients compared to the control group under the dominant and recessive genetic models. Moreover, the T allele was the risk factor for MS (P=0.002).

Our results provide evidence for a possible link between XRCC7 and the development of MS in the Iranian population. Therefore, further studies with larger sample sizes are required to support the findings of this research.