Association Study of IL-4 -590 C/T and DDX39B -22 G/C Polymorphisms with the Risk of Late-Onset Alzheimer's Disease in Iranian Population.

Interleukin-4 (IL-4), an important anti-inflammatory cytokine, is elucidated to regulate amyloid β-induced production of the inflammatory cytokines such as IL-1 and IL-6. It is assumed that IL-4 may involve in the inflammation pathology of surrounding senile plaques in Alzheimer's disease (AD) patients. DEAD (Asp-Glu-Ala-Asp) box polypeptide 39B (DDX39B), appears to be involved in regulation of the inflammatory cytokines which are in correlation with AD pathology. This study was conducted to investigate the two single nucleotide polymorphisms (SNPs), IL-4 -590 C/T and DDX39B -22 G/C, association with the risk of late-onset AD (LOAD) in Iranian population. In the present study, therefore, a cohort of 153 LOAD cases and 153 age-matched unrelated, non-dementia control subjects were analyzed for the two polymorphisms by polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP). Our results successfully demonstrate a protective association between the IL-4 -590 T allele, IL-4 -590 C/T heterozygous genotype (P= 0.01, OR= 0.53 and P= 0.041; OR= 0.56, respectively) and LOAD in Iranian population. A resemblance significant association was detected in female population when subjects were stratified by sex: the IL-4 -590 T allele (P= 0.02, OR= 0, 40) and the heterozygous genotype (P= 0.009, OR= 0.29). However, no significant association was observed between the DDX39B -22 G/C polymorphism in the cases and controls. Furthermore, it is clarified that the protective effect of IL-4 -590 is independent from APOE protective genotypes. Accordingly, the IL-4 -590 T allele may be applied as a protective marker in the development of LOAD in Iranian population.