Why Is Type 1 Diabetes Uncommon in Asia?

Abstract

T1D (type 1 diabetes) incidence rates are extremely low in Asian populations. The prevalences of islet-specific autoantibodies are reported to be low compared with Caucasians. Although the clinical and immunologic characteristics of T1D in Asians appear to be different from those of Caucasians, if we apply correct patient definition and standardized methods, the typical T1D patients are very similar, in the immunologic as well as genetic perspectives. Although the association of individual allele seems to be different between populations, if we compare the identical DR-DQ haplotypes, the association and transmission to diabetic offspring were similar for Asians and Caucasians. The high-risk HLA genotypes/haplotypes were found to be independent determinants of diabetes in the first-degree relatives of individuals with T1D, particularly in the presence of autoantibodies. A different genetic susceptibility including a low frequency of high-risk HLA alleles could explain the lower prevalence of islet-specific autoantibodies and the low incidence of T1D, or different genetic and environmental interactions might be involved in the etiology of T1D. It is certain that DR-DQ linkage disequilibrium (LD) is an important factor explaining the difference in T1D incidence in different countries. LD between highly susceptible DRB1 alleles and protective DQB1 alleles, and vice versa, is the major contributing factor to the low incidence of T1D in Asians. We also suggested that different genetic/environmental interactions might operate in the etiology of T1D between Caucasians and Asians. It would be of great help for primary prevention to investigate to what degree genetic determinants influence the well-known regional differences in incidences, since we can identify environmental risk factors that may either initiate the autoimmune process or promote already ongoing beta cell damage in different countries. For this, population-based epidemiological studies are necessary to identify risk determinants that may be useful for primary prevention strategies.

Evidence for the role of STAT4 as a general autoimmunity locus in the Korean population

“…A total of 418 Korean patients with T1D and 1060 healthy controls were recruited from the Seoul T1D Genetic Consortium [6,10] and a separate 428 AITD (241 Graves' disease and 187 Hashimoto's thyroiditis) patients were recruited from Hanyang University Endocrinology repository. All the T1D patients (M:F = 182:236) were less than 15 years old and had insulin therapy upon hospital discharge.…”

“…The development of T1D is governed by multiple susceptibility genes with the major locus in the HLA class II genes, and a number of minor loci with modest effects [6]. However, the influence on the genetic risk of all these genes cannot explain total familial aggregation of T1D [7].…”

Anti-Zinc Transporter Protein 8 Antibody Testing Is Not Informative in Routine Prediabetes Screening in Young Patients with Autoimmune Thyroiditis and Celiac Disease

“…Additional associations have been identified in the genes encoding HLA-A, HLA-B, HLA-C, and HLA-DP [27]. In almost all studies on Caucasians, positive associations between T1DM and DRB1*04:01-DQA1*03:01-DQB1*03:02 and DRB1*03:01-DQA1*05:01-DQB1*02:01 haplotypes have been observed, with the strongest association seen in the heterozygous high-risk haplotype [28,29,30,31,32,33]. …”

Macular Capillary Blood Flow in Patients with Diffuse Diabetic Macular Edema without Vitreomacular Traction

“…The incidence rate of type 1 diabetes is extremely low in Asian populations amounting to fewer than 1 case/year/100,000 individuals. In Caucasian populations, on the other hand, the incidence rate of type 1 diabetes is high with rates in excess of 20 cases/year/100,000 individuals [40] . The annual incidence rates in Seoul, Korea showed 0.6-2.2 cases/100,000 [41] .…”