The IFIH1rs1990760 polymorphism was genotyped in 1055 patients of Central-Eastern European ancestry with T1DM (median age at diagnosis: 8.2 [interquartile range, IQR 4.8-11.8] years).
Importantly, this MDA5-dependent antiviral response is specific to the pancreas of rotavirus-infected mice, similar to the autoimmunity associated with T1D.
In summary, our study uncovers an influence of rs1990760 on the canonical effector function of MDA5 in response to an acute infection of primary human parenchymal cells with a clinically relevant virus linked to human T1D.
These studies have provided a functional hypothesis for IFIH1T1D-associated SNPs' effects on MDA5-mediated interferon responses as well as supporting the genome-wide association (GWA) studies that first associated IFIH1 with T1D.
Associations of PTPN22, CTLA4, and IFIH1 variants with T1D were investigated in a sample of 197 nuclear families, including 205 affected children, in the Colombian population.
Our findings indicate that although STAT4 and IFIH1 SNPs are not associated with T1D in a Brazilian population, they might play a role in susceptibility to T1D on a larger worldwide scale.
The most significant association was with two T1D SNPs, rs12150079 (ZPBP2/ORMDL3/GSDMB region) (enterovirus frequency: AA 7.3%, AG 8.7%, GG 9.7%, RR = 0.86, overall p = 1.87E-02) and rs229541 (C1QTNF6/SSTR3/RAC2) (enterovirus frequency: CC 7.8%, CT 9.7%, TT 9.4%, RR = 1.13, overall p = 3.6E-02), followed by TLR8 (rs2407992) (p = 3.8E-02), TLR3 (1914926) (p = 4.9E-02), and two other T1D SNPs (IFIH1rs3747517, p = 4.9E-02 and PTPN22, rs2476601, p = 5.3E-02).
DNA variation in IFN-inducible genes altered T1D risk (P = 0.007), as exemplified by IFIH1, one of the genes in our IFN signature for which increased expression is a known risk factor for disease.
Using a relative gene expression method, we observed a lower expression of interferon-induced helicase 1 (IFIH1) and other type I IFN-induced genes in the blood cells of T1D subjects, especially subjects under 10 years old, in spite of their higher IFN levels as measured by the pSTAT1-inducing capacity of their sera.
The rs6432714, a tag-SNP that represents part of helicase domain of IF1H1 protein showed a trend of association only with T1D development (P>0.025 after Bonferroni adjustment) in log-additive model (OR=1.45, P=0.0365, power=0.99), indicating that helicase domain of IFIH1 protein could be associated with the susceptibility to T1D.
Here, we investigated whether this polymorphism is associated with T1DM or its clinical characteristics in a Brazilian population, and if IFIH1 gene expression in mononuclear cells from T1DM patients differs according to the genotypes of this polymorphism.
Previous investigations have indicated a role for IFIH1 in autoimmunity, as common and rare polymorphisms in this gene have been associated with type 1 diabetes.
Autoantibodies to insulin (IAA), GAD (GADA), insulinoma-associated antigen-2 (IA-2A) and zinc transporter 8 (ZnT8A) were measured in follow-up sera, and genotyping for type 1 diabetes susceptibility genes (HLA-DR/HLA-DQ, INS variable number of tandem repeats [VNTR] and single nucleotide polymorphisms at PTPN22, PTPN2, ERBB3, IL2, SH2B3, CTLA4, IFIH1, KIAA0350 [also known as CLEC16A], CD25, IL18RAP, IL10, COBL) was performed on the DNA samples of children born to a parent with type 1 diabetes and prospectively followed from birth for up to 22 years.
This meta-analysis demonstrates that the IFIH1rs1990760 T-allele confers susceptibility to T1D, SLE, MS and RA and suggests that the IFIH1 rs1990760 polymorphism might have no effect on GD and AAD.
The encoded protein (interferon-induced helicase C domain-containing protein 1) senses double-stranded RNA during replication of Picornavirales, including Enterovirus, a genus suspected in the etiology of type 1 diabetes.
USP18 depletion increases the expression of the T1D candidate gene MDA5, leading to an upregulation of double-stranded RNA-induced chemokine production.
Children of parents with type 1 diabetes and prospectively followed from birth for the development of islet autoantibodies and diabetes were genotyped for single-nucleotide polymorphisms at 12 type 1 diabetes susceptibility genes (ERBB3, PTPN2, IFIH1, PTPN22, KIAA0350, CD25, CTLA4, SH2B3, IL2, IL18RAP, IL10 and COBL).
Interestingly, cesarean section appeared to interact with immune response genes, including CD25 and in particular the interferon-induced helicase 1 gene, where increased risk for type 1 diabetes was only seen in children who were delivered by cesarean section and had type 1 diabetes-susceptible IFIH1 genotypes (12-year risk, 9.1 vs. <3% for all other combinations; P < 0.0001).