Yongsoo Park

A functional variant of SUMO4, a new I|[kappa]|B|[alpha]| modifier, is associated with type 1 diabetes

Previous studies have suggested more than 20 genetic intervals that are associated with susceptibility to type 1 diabetes (T1D), but identification of specific genes has been challenging and largely limited to known candidate genes. Here, we report evidence for an association between T1D and multiple single-nucleotide polymorphisms in 197 kb of genomic DNA in the IDDM5 interval. We cloned a new gene (SUMO4), encoding small ubiquitin-like modifier 4 protein, in the interval. A substitution (M55V) at an evolutionarily conserved residue of the crucial CUE domain of SUMO4 was strongly associated with T1D (P = 1.9 × 10−7). SUMO4 conjugates to IκBα and negatively regulates NFκB transcriptional activity. The M55V substitution resulted in 5.5 times greater NFκB transcriptional activity and ∼2 times greater expression of IL12B, an NFκB-dependent gene. These findings suggest a new pathway that may be implicated in the pathogenesis of T1D.

Prevalence of Diabetes and IGT in Yonchon County, South Korea

OBJECTIVE To determine the prevalence of diabetes and impaired glucose tolerance (IGT) in Yonchon County of South Korea and to investigate their associated factors. RESEARCH DESIGN AND METHODS We performed a population-based cross-sectional study with random cluster sampling of residents ≥30 years of age. Among the 3,804 residents sampled, a total of 2,520 participants had a standard 75-g oral glucose tolerance test and answered a detailed questionnaire. We also collected standard anthropometric data. RESULTS If the data for participants in the age range of 30–64 years were adjusted to the standard world population, the prevalence of diabetes was 7.2% and the prevalence of IGT was 8.9%. It was observed that the significant factors associated with diabetes were waist-to-hip circumference ratio, serum triglyceride levels, age, systolic blood pressure, family history of diabetes, and locality. CONCLUSIONS The prevalence of diabetes in Yonchon County was substantially higher than was previously suggested. The risk of diabetes increased with the increased central obesity and metabolic disturbances associated with insulin resistance.

Association of the polymorphism for Toll-like receptor 2 with type 1 diabetes susceptibility.

Abstract: Type 1 diabetes mellitus (T1DM) is a T cell‐mediated autoimmune disease in which pancreatic β cells are selectively destroyed. Although autoimmune diseases are driven by inappropriate adaptive immunity, innate immunity may play a role in the development of T1DM. We investigated the association of the genes for toll‐like receptor 2 (TLR2), one of the key surface receptors on innate effectors, with T1DM in Korean patients. Genetic association analyses revealed that the genotype composed of the rare allele (CC) of TLR2 1350 showed weak and protective association with T1DM (OR = 1.7, 95% CI: 1.1‐2.7; P < .05) irrespective of the duration of disease, age, and autoantibody status. One of the TLR2 SNP haplotypes, TLR2‐Ht4, was strongly associated with T1DM in that those subjects having more than one copy of Ht4 showed strong protection from developing T1DM (OR = 90.5; 95% CI: 13.8‐235.7; P < 10−5). The TLR2 polymorphisms are associated with T1DM, and distribution differences between T1DM versus controls were not influenced by the HLA genes. There is a close relationship between innate and adaptive immunity.

Risk factors for the development of NIDDM in Yonchon County, Korea

OBJECTIVE To determine the risk factors for the development of NIDDM in Yonchon County of Korea. RESEARCH DESIGN AND METHODS We studied 1,193 Korean nondiabetic subjects at baseline who participated in a 2-year follow-up study on diabetes in Yonchon County. A 75-g oral glucose tolerance test was performed 2 years after the baseline examination. Age, sex, and anthropometric and metabolic characteristics at baseline were analyzed simultaneously as potential predictors of conversion to NIDDM. We also designed a nested case-control study to determine the role of hyperinsulinemia and/or hyperproinsulinemia in the conversion to NIDDM in patients with newly developed diabetes and control subjects matched for age, sex, BMI, and waist-to-hip-ratio. RESULTS At 2 years, 67 subjects developed diabetes, as defined by World Health Organization criteria. The age-adjusted incidence was significantly higher in men (6.4%) than in women (3.0%), and the incidence increased as age increased in both sexes. Multiple logistic regression analysis revealed age, male sex, and fasting and 2-h glucose levels to be significant risk factors for the development of NIDDM, whereas waist-to-hip ratio and BMI were not. In a nested case-control study, baseline proinsulin but not insulin levels were significantly higher in subjects who progressed to NIDDM than in those who did not. CONCLUSIONS In the Korean population, β-cell dysfunction, as measured by high proinsulin levels, seems to be associated with subsequent development of NIDDM, whereas regional and general obesity and fasting insulin levels, which may be a surrogate for insulin resistance, were not.

Genetic susceptibility factors of Type 1 diabetes in Asians

Type 1 diabetes is a multifactorial disease in which the insulin producing β‐cells of the pancreas are destroyed by the immune system, a process determined by the activity of major histocompatibility complex (MHC)‐restricted T lymphocytes. Progress has been made in elucidating genetic factors involved in Type 1 diabetes in Caucasians, with less data available from Asia. For Asians, the human MHC locus (HLA region), especially the class II region, is the major susceptibility interval. The role of IDDM2, the insulin locus, has been questioned in Asia. In contrast to Caucasians, Asian populations have a very low incidence of Type 1 diabetes (0.4–1.1 cases/year/100 000 individuals). This low incidence rate in the Asian population may be related to the population frequency distribution of susceptible Type 1 diabetes genes, especially of HLA. The overall risk for Type 1 diabetes from HLA DR and DQ is determined by polymorphic residues (alleles) and particular combinations of alleles (haplotypes and genotypes) in a given individual. In Asians, it is very common that a protective DR4 allele is associated with susceptible DQ alleles while neutral/protective DQ alleles are associated with the susceptible DR4 alleles. Our analyses indicate that the counterbalancing between susceptible DRB1 and protective DQB1, and vice versa, is a factor that may contribute to the low incidence of diabetes in Asians. We find that identical HLA DRB1‐DQB1 haplotypes of Asians and Caucasians have similar transmission to diabetic children and similar associations with diabetes. Moreover, the association with diabetes and transmission to a diabetic offspring of DR4 haplotypes varies depending on the haplotype borne on the homologous chromosome. This might contribute not only to the synergistic effect of DR3/4, but also to the susceptibility influence of DQB1*0401 haplotypes confined to DR4/X. High‐risk DR4 subtypes were predominant in DR4/X, whereas protective DR4 subtypes were observed mainly in the DR3/4 genotype. Since in Asians DQB1*0401 is in linkage disequilibrium (LD) with DRB1*0405, we find more DRB1*0405‐DQB1*0401 haplotypes in patients with DR4/X than in patients with DR3/4, suggesting that the contribution of the DRB1 locus may be greater in DR4/X than in DR3/4 genotypes. Several genome scans suggested additional susceptibility intervals and provided supporting evidence for several previously reported linkages. Other studies focused on the confirmation of linkage using multipoint sib‐pair analyses with densely spaced markers and multiethnic collection of families. Although significant and consistent linkage evidence was reported for the susceptibility intervals IDDM12 (on 2q33) even in Asia, evidence for most other intervals varies in different data sets. LD mapping has become an increasingly important tool for both confirmation and fine‐mapping of susceptibility intervals, as well as identification of etiological mutations. The examination of large and ethnically varied data sets including those of Asia has allowed identification of haplotypes that differ only at a single codon in a single locus. As more data become available, the study of pairs of haplotypes which differ at a single polymorphic site, but have different effects on disease susceptibility, should allow more precise definition of the polymorphisms involved in the disease process. Copyright

Combinations of HLA DR and DQ molecules determine the susceptibility to insulin-dependent diabetes mellitus in Koreans

The association of HLA-DRB1 and DQB1 genes with IDDM in Koreans was assessed using 115 IDDM patients and 140 nondiabetic controls. DQB1*0201 is the only DQB1 allele positively associated with IDDM while DQB*0602, *0601 and *0301 are negatively associated. Three DRB1 alleles (DRB1*0301, DRB1*0407 and DRB1*0901) are positively associated while four DR allele groups (DRB1*15, DRB1*12, DRB1*10 and DRB1*14) are negatively associated. However, Haplotype analyses indicated that DQB1*0302, DRB1*0405 and DRB1*0401 may confer susceptibility because the DRB1*0405-DQB*0302 and DRB1*0401-DQB1*0302 haplotypes are positively associated with the disease. The lack of association in Koreans with the DQB1*0302 allele, which appears predisposing in studies of non-Orientals, is due to its strong linkage disequilibrium (LD) with the protective DRB1*0403 and *0406 alleles, while the lack of association with DRB1*0405 is because of its strong LD with the protective DQB1*0401 allele. Nine DR/DQ genotypes confer significantly increased risk to IDDM. Seven of the nine genotypes (DR3/4s, DR1/4s, DR4s/13, DR4s/8, DR4s/7, DR9/13 and DR3/9) were also found to be at high risk to IDDM in other populations, while the two others (DR1/9 and DR9/9) are only found in Koreans. Surprisingly, DR4/4 homozygotes are not associated with high risk to IDDM in Koreans. This observation can be explained by the high frequency of protective DR4 subtypes and the protective DQ alleles (0301 and 0401) associated with the susceptible DR4 alleles. Our analyses indicate that the counterbalancing act between susceptible DRB1 and protective DQB1, and vice versa, that has already been observed in Chinese and Japanese, is the major factor responsible for the low incidence of diabetes in Koreans.

C1q/TNF-Related Protein-3 (CTRP-3) and Pigment Epithelium-Derived Factor (PEDF) Concentrations in Patients With Type 2 Diabetes and Metabolic Syndrome

Recent studies have suggested that a novel adipokine, C1q/tumor necrosis factor-related protein-3 (CTRP-3), a paralog of adiponectin, may play an important role in the regulation of glucose metabolism and innate immunity. Pigment epithelium-derived factor (PEDF), a multifunctional protein with antioxidant and anti-inflammatory properties, is associated with insulin resistance and metabolic syndrome. We examined circulating CTRP-3 and PEDF concentrations in 345 subjects with diverse glucose tolerance statuses. Furthermore, we evaluated the involvement of CTRP-3 and PEDF with cardiometabolic risk factors including insulin resistance, high-sensitivity C-reactive protein (hsCRP), estimated glomerular filtration rate (eGFR), and brachial-ankle pulse wave velocity (baPWV). CTRP-3 concentrations were significantly higher in patients with type 2 diabetes or prediabetes than the normal glucose tolerance group, whereas PEDF levels were not different. Subjects with metabolic syndrome showed significantly higher levels of both CTRP-3 and PEDF compared with subjects without metabolic syndrome. Both CTRP-3 and PEDF were significantly associated with cardiometabolic parameters, including waist-to-hip ratio, triglycerides, HDL-cholesterol, alanine aminotransferase, eGFR, hsCRP, and baPWV. In conclusion, circulating CTRP-3 concentrations were elevated in patients with glucose metabolism dysregulation. Both CTRP-3 and PEDF concentrations were increased in subjects with metabolic syndrome and associated with various cardiometabolic risk factors.

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 β 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.

The Low Prevalence of Immunogenetic Markers in Korean Adult-Onset IDDM Patients

OBJECTIVE IDDM is an autoimmune disease that occurs among genetically susceptible individuals. In Asian populations, it is not uncommon for adult patients with NIDDM to eventually lose β-cell function and develop IDDM. These individuals may be characterized by autoantibodies to GAD and high-risk HLA-DQ alleles, which are unlikely to be prevalent among patients with true NIDDM or in the general population. The objective of the present study was to evaluate and compare the prevalence of these immunogenetic markers in NIDDM patients and healthy nondiabetic individuals from Korea. RESEARCH DESIGN AND METHODS The prevalences of anti-GAD antibodies and HLA-DQA1 and DQB1 alleles among 121 patients with newly diagnosed NIDDM identified from a population-based study in Yonchon, Korea, and 100 matched healthy control subjects were evaluated and compared. RESULTS The overall prevalence of anti-GAD antibodies was 1.7% (2 of 121) in patients with previously undiagnosed NIDDM, whereas 1 of 100 control subjects had a positive test for antibodies. Among those who tested positive, titers of antibodies to GAD were not high. No statistically significant differences in the distributions of either mean levels of anti-GAD antibodies or DQA1 and DQB1 alleles were found comparing NIDDM patients with control subjects. Interestingly, the frequency of DQB1*non-Asp-57 and DQA1*Arg-52 alleles in the Korean adult control population was similar to that in the U.S. white population (DQB1*non-Asp-57: 0.431 vs. 0.475; DQA1*Arg-52: 0.492 vs. 0.463). CONCLUSIONS The low prevalence of anti-GAD antibodies and HLA-DQA1 and DQB1 susceptibility alleles among recent-onset NIDDM patients, which was similar to observations in control subjects, suggests that diabetes in Korean adults is unlikely to have an autoimmune component to its pathogenesis.

Insulin degludec/insulin aspart versus biphasic insulin aspart 30 in Asian patients with type 2 diabetes inadequately controlled on basal or pre-/self-mixed insulin: A 26-week, randomised, treat-to-target trial

AIMS Insulin degludec/insulin aspart (IDegAsp) is a soluble co-formulation of IDeg and IAsp. This pan-Asian, 26-week trial investigated efficacy and safety of IDegAsp vs biphasic insulin aspart 30 (BIAsp 30) in Asian adults with type 2 diabetes (T2DM), inadequately controlled on once- or twice-daily (BID) basal, premixed or self-mixed insulin. METHODS Participants (mean age 59.8 years, HbA1c 8.4%, FPG 7.9 mmol/L, BMI 25.4 kg/m(2)) were randomised 2:1 to BID IDegAsp (n=282) or BIAsp 30 (n=142) and continued existing metformin treatment. Insulins were administered with breakfast and main evening meal, titrated to a pre-breakfast and pre-main evening meal self-measured plasma glucose target of 4-5 mmol/L. RESULTS IDegAsp achieved the primary endpoint of non-inferiority to BIAsp 30 for mean change in HbA₁c (estimated treatment difference [ETD] IDegAsp-BIAsp 30: 0.05% points [95% CI -0.10; 0.20]). IDegAsp was superior in lowering fasting plasma glucose (FPG) (ETD -1.06 mmol/L, 95% CI -1.43; -0.70, p<0.001), and resulted in a lower final mean daily insulin dose (0.79 U/kg vs 0.99 U/kg, estimated rate ratio [RR] 0.79, 95% CI 0.73; 0.85, p<0.0001). Rates of overall confirmed and severe hypoglycaemia were similar between treatments, while rate of nocturnal confirmed hypoglycaemia was numerically (p=ns) lower with IDegAsp. During the maintenance period there was a trend (p=ns) towards lower hypoglycaemia rates for IDegAsp. CONCLUSION In Asian adults with T2DM, IDegAsp BID effectively improves long-term glycaemic control, and compared to BIAsp 30, provides superior reductions in FPG with a lower dose, and numerically less nocturnal hypoglycaemia.