OBJECTIVEBetatrophin, a newly identified hormone, has been recently characterized as a potent stimulator that increases the production and expansion of insulin-secreting b-cells in mice, but the physiological role of betatrophin remains poorly understood. This study measured for the first time serum betatrophin levels in newly diagnosed patients with type 2 diabetes (T2DM) and explored the correlations between its serum levels and various metabolic parameters in T2DM.
RESEARCH DESIGN AND METHODSWe analyzed the concentrations of betatrophin by ELISA in blood samples of 166 well-characterized individuals in whom anthropometric parameters, oral glucose tolerance test (OGTT), glycosylated hemoglobin, blood lipids, insulin sensitivity (1/homeostasis model assesment of insulin resistance [1/HOMA-IR] and Matsuda index [ISI M ]), and insulin secretion were measured. The participants were divided into newly diagnosed T2DM patients (n = 83) and age-, sex-and BMI-matched healthy control subjects (n = 83).
RESULTSSerum betatrophin levels were significantly higher in T2DM patients than in healthy control subjects (613.08 [422.19-813.08] vs. 296.57 [196.53-509.46] pg/mL; P < 0.01). Serum betatrophin positively correlated with age, 2-h post-OGTT glucose (2hPG), and postprandial serum insulin (PSI), but negatively with 1/HOMA-IR and ISI M in T2DM patients. In the control group, betatrophin was only positively associated with age. In T2DM subjects, multivariate regression analyses showed that age, 2hPG, and PSI were independent factors influencing serum betatrophin levels.
CONCLUSIONSCirculating concentrations of betatrophin are significantly increased in T2DM patients. Our results suggest that betatrophin may play a role in the pathogenesis of T2DM.Precise regulation of b-cell function is crucial for maintaining blood glucose homeostasis (1). In type 2 diabetes (T2DM), ambient insulin resistance forces b-cells to produce more insulin, which ultimately results in exhaustion of insulin production secondary to deterioration of b-cell functions. Unfortunately, neither pharmacotherapy nor insulin injections can reverse ongoing failure of b-cell function to prevent uncontrolled hyperglycemia and the devastating microvascular, neurologic, and macrovascular complications of diabetes. Treatments that replenish b-cell
Graves' disease is a common autoimmune disorder characterized by thyroid stimulating hormone receptor autoantibodies (TRAb) and hyperthyroidism. To investigate the genetic architecture of Graves' disease, we conducted a genome-wide association study in 1,536 individuals with Graves' disease (cases) and 1,516 controls. We further evaluated a group of associated SNPs in a second set of 3,994 cases and 3,510 controls. We confirmed four previously reported loci (in the major histocompatibility complex, TSHR, CTLA4 and FCRL3) and identified two new susceptibility loci (the RNASET2-FGFR1OP-CCR6 region at 6q27 (P(combined) = 6.85 × 10(-10) for rs9355610) and an intergenic region at 4p14 (P(combined) = 1.08 × 10(-13) for rs6832151)). These newly associated SNPs were correlated with the expression levels of RNASET2 at 6q27, of CHRNA9 and of a previously uncharacterized gene at 4p14, respectively. Moreover, we identified strong associations of TSHR and major histocompatibility complex class II variants with persistently TRAb-positive Graves' disease.
Graves' disease (GD), characterized by autoantibodies targeting antigens specifically expressed in thyroid tissues causing hyperthyroidism, is triggered by a combination of genetic and environmental factors. However, only a few loci for GD risk were confirmed in the various ethnic groups, and additional genetic determinants have to be detected. In this study, we carried out a three-stage study in 9529 patients with GD and 9984 controls to identify new risk loci for GD and found genome-wide significant associations in the overall populations for five novel susceptibility loci: the GPR174-ITM2A at Xq21.1, C1QTNF6-RAC2 at 22q12.3-13.1, SLAMF6 at 1q23.2, ABO at 9q34.2 and an intergenic region harboring two non-coding RNAs at 14q32.2 and one previous indefinite locus, TG at 8q24.22 (Pcombined < 5 × 10(-8)). The genotypes of corresponding variants at 14q32.2 and 8q24.22 were correlated with the expression levels of C14orf64 and a TG transcript skipping exon 46, respectively. This study increased the number of GD loci with compelling evidence and indicated that non-coding RNAs might be potentially involved in the pathogenesis of GD.
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