Association between cytokine genes polymorphisms and type 1 diabetes: a case-control study on Saudi population

Association studies of genes encoding cytokines that play an important role in inflammatory response represent one approach to finding type 1 diabetes (T1D) disease genes. The aim of this study was to investigate the association of single nucleotide polymorphisms (SNPs) within cytokine genes with T1D in a cohort of Saudi subjects.

A total of 300 well-characterized type 1 diabetic patients and 300 T1D-free control subjects were enrolled in this investigation. Cytokine SNPs were genotyped by using Polymerase chain reaction (PCR) with sequence-specific primers.

Our data revealed that IFN-γ +874T allele carriers [odds ratio (OR) = 1.87, p < 0.001] and TT homozygotes (OR = 1.28, p < 0.001) were significantly more susceptible to developing T1D than the A allele carriers. In addition, TNF-α -308A allele carriers (OR = 1.73, p < 0.001) and AA homozygotes (OR = 1.74, p < 0.001) were also overrepresented among the diabetics than G allele carriers. IL-4 -590C/T TT homozygotes (OR = 2.23, p < 0.001) were significantly more susceptible to develop T1D than CC genotypes, whereas CT heterozygotes were not significantly associated (OR = 1.43, p = 0.78) with T1D. Furthermore, IL-4 T allele was statistically associated with T1D patients compared to control group (OR = 2.24, p < 0.001). Similarly, IL-1β -511C/T TT homozygotes (OR = 1.85, p = 0.012) and the T allele (OR = 1.85, p < 0.001) were significantly more susceptible to T1D than CC genotypes, whereas TC heterozygotes (OR = 1.04, p = 0.86) were not significantly associated with T1D.

Our data concluded that IFN-γ +874T allele, TNF-α -308A allele, IL-1β -511T allele, and IL-4 -590T allele could be considered risk factors for T1D development in Saudi subjects.