Association of type 1 diabetes with two Loci on 12q13 and 16p13 and the influence coexisting thyroid autoimmunity in Japanese.

CONTEXT: Recent genome-wide association studies have identified several novel type 1 diabetes (T1D) loci in white populations. OBJECTIVE: In line with recent findings, we conducted a replication study of two loci on chromosome 12p13 and 16p13 and assessed their potential associations with thyroid autoimmunity in a Japanese population. SUBJECTS AND METHODS: Two single-nucleotide polymorphisms (SNPs), rs2292399 in ERBB3 on 12q13 and rs2903692 in CLEC16A (or KIAA0350) on 16p13, were analyzed in Japanese subjects consisting of 735 T1D patients, 330 patients with autoimmune thyroid disease (AITD), and 621 control subjects. RESULTS: According to a case-control study and logistic regression adjusting for sex and age, we observed that these SNPs in ERBB3 and CLEC16A were both significantly associated with T1D, with the risk alleles being consistent with those in white populations [adjusting odds ratio by multiplicative model: 1.37 (1.13-1.67), P = 0.001; and 1.28 (1.02-1.60), P = 0.030, respectively]. In both SNPs, the association was suggested to be stronger in T1D complicated with AITD (Graves' disease, Hashimoto's thyroiditis, or thyroid autoantibodies). Furthermore, a joint analysis, with the INS and CTLA4 SNPs, revealed that CTLA4 rs3087243, ERBB3 rs2292399, and CLEC16A rs2903692, but not INS rs689, were significant risk factors for the cooccurrence of AITD in Japanese T1D. CONCLUSION: We confirmed two loci on 12q13 and 16p13 that were identified by the independent genome-wide association studies in white populations, thus suggesting that these loci contribute to T1D susceptibility across different ethnic groups. In addition, these loci may also be associated with the cooccurrence of thyroid autoimmunity in T1D.

Promoter polymorphisms of the pigment epithelium-derived factor gene are associated with diabetic retinopathy.

Pigment epithelium-derived factor (PEDF or SERPINF1), a neuroprotective and anti-angiogenic factor, may play an important role in the pathogenesis of diabetic retinopathy (DR). In 416 patients with type 2 diabetes, four polymorphisms in the PEDF SNPs were identified, rs12150053 and rs12948385 in the promoter region, rs9913583 in the 5'-untranslated region, and rs1136287 (Met72Thr) in exon 3. Based on case-control studies, rs12150053 and rs12948385, but not rs9913583 and rs1136287, were significantly associated with DR. A logistic regression analysis revealed that the TC or CC genotype of rs12150053 was a significant risk factor for DR (odds ratio 2.40, p=0.0004). The GA or AA genotype of rs12948385 was also a significant risk factor for DR. In addition, a significant interaction between the vascular endothelial growth factor (VEGF) and PEDF SNPs in the susceptibility to DR was found. These results demonstrate that the PEDF gene, in cooperation with the VEGF gene, may contribute to the development of DR.

Insulin gene/IDDM2 locus in Japanese type 1 diabetes: contribution of class I alleles and influence of class I subdivision in susceptibility to type 1 diabetes.

CONTEXT: It is suggested that insulin autoimmunity plays an important role in the development of type 1 diabetes in humans. However, the association between insulin gene (INS) region (IDDM2) and type 1 diabetes has been uncertain in Asians. OBJECTIVE: A multicenter collaboration study was conducted to clarify the role of the IDDM2 region in Japan. SUBJECTS AND METHODS: In total, 661 patients with type 1 diabetes and 706 control subjects were enrolled. The INS variable number of tandem repeat (VNTR) class I/class III status was estimated by genotyping the -23 HphI single nucleotide polymorphism. From surrounding polymorphisms across the insulin gene, we also inferred haplotypes bearing INS VNTR lineages. RESULTS: The frequency of the class I allele was 99.3% in patients and 96.7% in controls (P < 10(-5)), and the class I/III or III/III genotype was found in 1.4% of patients and in 6.4% of controls [odds ratio (OR) 0.20, P < 10(-5)]. The class I subdivision revealed IC to increase significantly in patients with type 1 diabetes (P = 0.002), whereas ID did not; the distribution of IC and ID was significantly different between patients and controls (P = 0.014). CONCLUSION: The present study certainly shows that the IDDM2 region is also a susceptibility locus in the Japanese population. Furthermore, it was revealed that IC may be more susceptible to type 1 diabetes than ID, which could be evidence that the INS VNTR itself confers susceptibility to type 1 diabetes.

Functional VEGF C-634G polymorphism is associated with development of diabetic macular edema and correlated with macular retinal thickness in type 2 diabetes.

Since vascular endothelial growth factor (VEGF) has a strong effect on induction of vascular permeability, VEGF is an attractive candidate gene for development of diabetic macular edema (ME). Among the 378 patients with type 2 diabetes studied, 203 patients had no retinopathy, 93 had non-proliferative diabetic retinopathy (NPDR), and 82 had proliferative diabetic retinopathy (PDR). ME was present in 16 patients with NPDR and 47 patients with PDR. We genotyped three VEGF polymorphisms: C-2,578A, G-1,154A, and C-634G. Genotype and allele distribution of C-634G, but not C-2,578A or G-1,154A, were significantly different between patients with and without diabetic retinopathy. Logistic regression analysis revealed that the C-634G genotype was a risk factor for DR (p = 0.002), and furthermore for ME (p = 0.047), independently from severity of DR, with the -634C allele increasing the risk. Macular thickness measured by optical coherence tomography was correlated with the C-634G genotype, with the trend increasing with the presence of more -634C alleles (p = 0.006). Stepwise regression analysis showed that duration of diabetes and presence of the C-634G genotype were independent predictors of macular thickness. In addition, basic transcriptional activity levels associated with the -634C allele were greater compared to those seen with the -634G allele in human glioma and lymphoblastic T-lymphocyte cells. These results demonstrate that the VEGF C-634G polymorphism is a genetic risk factor for ME as well as DR.

Endothelial nitric oxide synthase gene is associated with diabetic macular edema in type 2 diabetes.

OBJECTIVE: We examined the endothelial nitric oxide (eNOS) gene polymorphisms to assess its possible association with diabetic retinopathy and macular edema. RESEARCH DESIGN AND METHODS: A total of 226 patients with type 2 diabetes and 186 healthy subjects were studied. Type 2 diabetic patients consisted of 110 patients without retinopathy, 46 patients with nonproliferative diabetic retinopathy, and 71 patients with proliferative diabetic retinopathy. Diabetic macular edema was present in 48 patients. Three polymorphisms of the eNOS gene were determined: T-786C in the promoter region, 27-bp repeat in intron 4, and Glu298Asp in exon 7. RESULTS: Close linkage disequilibrium was observed between the T-786C polymorphism and the 27-bp repeat, as has been previously reported, but Glu298Asp was not in linkage disequilibrium with the other two polymorphisms. The eNOS gene polymorphisms were not significantly associated with the presence of retinopathy or with retinopathy severity or type 2 diabetes itself. However, by both association study and multiple logistic regression analysis, the T-786C and 27-bp repeat polymorphisms were significantly associated with a risk of developing macular edema with the -786C allele and the "a" allele increasing the risk. CONCLUSIONS: The present study suggests that the eNOS gene is a novel genetic risk factor for diabetic macular edema. The eNOS gene polymorphisms may contribute to the development of macular edema by impairing basal eNOS expression and resulting in the breakdown of the blood-retina barrier.