Association analysis of myosin IXB and type 1 diabetes.

To date, seven studies have provided evidence for an association between the gene encoding for myosin IXB (MYO9B) and celiac disease (CD), and inflammatory bowel diseases, including single nucleotide polymorphisms (SNPs) rs2305767, rs1457092, and rs2305764. We investigated whether MYO9B is associated with T1D. The three SNPs were genotyped in Dutch samples from 288 T1D patients and 1615 controls. The A allele of SNP rs2305767A>G showed some evidence of association with T1D (nominal p for genotype = 0.06; OR carrier = 1.51, 95% CI = 1.04-2.19), but not in British samples from 4301 case patients and 4706 controls (p = 0.53), or when the Dutch and UK data were pooled (N patients = 4582, N controls= 6224; Mantel-Hansel p = 0.83). Furthermore, the nonsynonymous rs1545620 C>A SNP that has been associated with the inflammatory bowel disease, showed no association with T1D in British case-control set (p = 0.57). We conclude that MYO9B might not be a strong determinant of T1D, although there was some association in our initial Dutch study. Further studies are needed to evaluate the role of MYO9B in T1D.

Association analysis of functional variants of the FcgRIIa and FcgRIIIa genes with type 1 diabetes, celiac disease and rheumatoid arthritis.

FcgRIIa and FcgRIIIa are potent modulators of the immune system which bind (auto)antibodies and activate immune cells. The FcgRIIa*A519G and FcgRIIIa*A559C functional variants have been associated with several immune-related diseases. We studied FcgRIIa*A519G and FcgRIIIa*A559C SNPs in type 1 diabetes (T1D), celiac disease (CD) and rheumatoid arthritis (RA) patients and controls and included a meta-analysis of all recent studies of FcgRIIIa*A559C and RA. Our cohorts comprised 350 T1D, 519 CD, 639 RA patients and 1359 controls, who were genotyped for FcgRIIa*A519G and FcgRIIIa*A559C variants. Regression and expectation maximization (EM) algorithm-based haplotype analyses were used for the data analysis. We found significant differences in genotype frequencies of FcgRIIa between controls and patients with T1D (P = 0.04), CD (P = 0.000005) and RA (P = 0.04). The FcgRIIa*519GG genotype showed an increased risk for both T1D [odds ratio (OR) = 1.51; 95% confidence interval (95% CI) 1.08-2.12; P = 0.015] and CD (OR = 1.81; 95% CI 1.35-2.37; P = 0.000004), but not for RA. There was no difference in the frequency of FcgRIIIa*A559C genotypes or allelotypes between controls with T1D, CD and RA. We found that FcgRIIa and FcgRIIIa haplotype frequencies differed significantly between controls and patients with T1D (P = 0.05) and with CD (P = 0.00038) but not with RA. Our meta-analysis showed a significant 1.37(95% CI 1.14-1.66)-fold increased risk of RA for the FcgRIIIa*559CC (158VV) genotype (P = 0.001). This is the first report that the FcgRIIa*519GG genotype predisposes to T1D and CD. We confirmed that the FcgRIIIa*559CC genotype is associated with RA. If replicated, our findings would suggest FcgRIIa*519G as a common risk factor for auto-immune diseases. This may have clinical implications with regard to efficacy or safety of antibody-based immuno-modulator therapies.

MYO9B gene polymorphisms are associated with autoimmune diseases in Spanish population.

The aim of the study was to test MYO9B gene polymorphisms for association with three autoimmune diseases, systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and celiac disease (CD), in a Spanish population. We analyzed three SNPs (rs2305767, rs1457092, and rs2305764) in a case-control cohort composed of 349 SLE patients, 356 RA patients, 90 CD patients, and 345 healthy controls. All three SNPs showed a consistent increased frequency of the A allele in SLE, RA, and CD patients compared with healthy controls. An association was observed between CD and rs2305764 (p=0.01, OR=2.3), between SLE and rs1457092 (p=0.002, OR=1.4), and between RA and rs1457092 (p=0.02, OR=1.3). The three autoimmune diseases combined showed significant association with rs1457092 and rs2305764 and with the AAA haplotype (p haplotype=0.005, OR=1.3). Our data demonstrate consistent association with the A allele and AAA haplotype of three SNPs in the MYO9B gene, which were previously reported to be associated with CD in the Dutch population. This suggests that genetic variation in MYO9B is associated with CD, SLE, and RA and that MYO9B is a general risk factor for autoimmunity.

MICA marks additional risk factors for Type 1 diabetes on extended HLA haplotypes: an association and meta-analysis.

The association of the HLA complex on chromosome 6 does not explain total linkage of the HLA region to Type 1 Diabetes (T1D), leading to the hypothesis that there may be additional causal genes in the HLA region for immune-related disorders. Reports on the MHC Class I chain-related A (MICA) gene as candidate for association with T1D are contradicting. We investigated whether variation in MICA is associated to T1D in a cohort of 350 unrelated individuals with juvenile-onset T1D and 540 control subjects, followed by a meta-analysis of 14 studies. We also investigated an HLA-independent association for MICA with T1D. In our case-control study, we found that the MICA*A5 variant was significantly associated with an increased risk for T1D, while MICA*A6 was significantly associated with a decreased risk that was confirmed by our meta-analysis. However, the meta-analysis did not show an association of MICA*A5 T1D. Analysis of MICA alleles conditional on T1D-associated high-risk MHC class II haplotypes revealed that MICA*A6 was associated with an increased risk for T1D when this marker co-occurred with HLA DQ2DR17 T1D-risk-haplotypes. In contrast, MICA*A6 reduced the risk from the HLA DQ8DR4 T1D-risk haplotype. Moreover, MICA*A9 showed a significant association to increased risk for T1D on DQ8DR4 haplotypes. Co-inheritance of MICA*A6 with the HLA DQ2DR17 haplotype in T1D indicates this haplotype may carry the additional genetic factors for T1D, but our study does not support an independent association between MICA variants and T1D.