HLA-typing, clinical, and immunological characterization of youth with type 2 diabetes mellitus phenotype from the German/Austrian DPV database.

AIM: To characterize the clinical and immunological features of HLA-typed youth with pediatric onset of type 2 diabetes mellitus (T2DM). METHOD: One hundred and seven patients with clinically diagnosed T2DM (aged ≤20 yr at diagnosis) were examined. DNA and serum, obtained after a median diabetes duration of 2.2 (Q1-Q3: 0.8-4.6) yr, were used for centralized HLA-typing and autoantibody (GADA, IA-2A, ZnT8A) measurements. RESULTS: 64.6% of patients were female and median age at diagnosis was 13.8 (Q1-Q3: 11.6-15.4) yr. Patients were obese [median body mass index-standard deviation score (BMI-SDS): 2.6 (2.0-3.1)], 88.0% had a family history of diabetes and 40.2% a migration background. Islet autoantibodies were detected in 16 (15.0%), among which 7 (6.5%) had multiple islet autoantibodies. Autoantibody positive patients had poorer metabolic control than autoantibody negative patients [glycosylated hemoglobin A1c (HbA1c): 8.1 (6.9-10.1) % vs. 6.6 (5.9-8.0) %; p = 0.033], while patients with HLA-DR genetic risk had higher BMI-SDS than those with HLA-DRXX [2.6 (2.4-3.7) vs. 2.4 (1.7-2.9); p = 0.007]. Metabolic syndrome (61.7%), microalbuminuria (13.4%), and retinopathy (3.9%) were diagnosed. Therapies used were lifestyle only (35.5%), oral anti-diabetics (OAD) only (43.3 %), insulin + OAD (15.9%) and insulin only (5.6%). Patients with ß-cell autoimmunity or HLA-DR genetic risk more frequently used insulin than confirmed T2DM patients (50.0 vs. 22.0%; p = 0.037) and less often had diabetic relatives (61.1 vs. 86.0%; p = 0.030). CONCLUSION: T2DM was confirmed in about 90% of patients while about 10% with ß-cell autoimmunity or HLA-DR genetic risk likely had either T1.5DM or 'double diabetes' or an unknown diabetes type.

Collection and processing of whole blood for transformation of peripheral blood mononuclear cells and extraction of DNA: the Type 1 Diabetes Genetics Consortium.

BACKGROUND: and PURPOSE: To yield large amounts of DNA for many genotype analyses and to provide a renewable source of DNA, the Type 1 Diabetes Genetics Consortium (T1DGC) harvested DNA and peripheral blood mononuclear cells (PBMCs) from individuals with type 1 diabetes and their family members in several regions of the world. METHODS: DNA repositories were established in Asia-Pacific, Europe, North America, and the United Kingdom. To address region-specific needs, different methods and sample processing techniques were used among the laboratories to extract and to quantify DNA and to establish Epstein-Barr virus transformed cell lines. RESULTS: More than 98% of the samples of PBMCs were successfully transformed. Approximately 20-25 microg of DNA were extracted per mL of whole blood. Extraction of DNA from the cell pack ranged from 92 to 165 microg per cell pack. In addition, the extracted DNA from whole blood or transformed cells was successfully utilized in each regional human leukocyte antigen genotyping laboratory and by several additional laboratories performing consortium-wide genotyping projects. LIMITATIONS: Although the isolation of PBMCs was consistent among sites, the measurement of DNA was difficult to harmonize. CONCLUSIONS: DNA repositories can be established in different regions of the world and produce similar amounts of high-quality DNA for a variety of high-throughput genotyping techniques. Furthermore, even with the distances and time necessary for transportation, highly efficient transformation of PBMCs is possible. For future studies/trials involving several laboratories in different locations, the T1DGC experience includes examples of protocols that may be applicable. In summary, T1DGC has developed protocols that would be of interest to any scientific organization attempting to overcome the logistical problems associated with studies/trials spanning multiple research facilities, located in different regions of the world.

Level of an advanced glycated end product is genetically determined: a study of normal twins.

Reducing sugars react with amino groups in proteins, lipids, and nucleic acids to produce advanced glycation end products (AGEs), including N(epsilon)-carboxymethyl lysine (CML), which have been implicated in oxidative stress and vascular damage. The aim of this study was to determine whether genetic factors influence serum CML levels in normal subjects. We performed a classical twin study of CML in healthy nondiabetic female twins, 39 monozygotic and 45 dizygotic pairs, aged 21-74 years. Serum CML levels were estimated by enzyme-linked immunosorbent assay. Twin correlations (r) for serum CML levels were higher in monozygotic (r = 0.71) compared with dizygotic (r = 0.50) twin pairs, suggesting a substantial genetic effect and confirmed by quantitative genetic model fitting. Additive genetic effects (heritability) explained 74% (95% CI 58-84) of population variance in CML. Heritability (%) of fasting glucose (51%) and HbA(1c) (62%) could not explain CML heritability, which was not associated with them. CML levels are, therefore, predominantly genetically determined and independent of genes influencing fasting glucose or HbA(1c). Thus familial, largely genetic factors influence AGE implicating these glycoxidation products in the genetic contribution to macro- and microvascular disease.