[Genetic background in common forms of obesity - from studies on identical twins to candidate genes of obesity]. / Genetické pozadí bezných forem obezity - od studií identických dvojcat po studium kandidátních genu obezity*

Common obesity is a result of interaction between genes and environmental/lifestyle factors, with heritability estimates 40-70%. Not only the susceptibility to obesity but also the success of weight management depends on the genetic background of each individual. This paper summarizes the up-to-date knowledge on genetic causes of common obesities. Introduction of genome-wide association studies (GWAS) led to an identification of a total of 32 variants associated with obesity/BMI and 14 with body fat distribution. Further, a great progress in revealing the mechanisms regulating the energy balance was also noted. However, the proportion of explained variance for BMI is still low, suggesting other mechanisms such as gene-gene and gene-environment interactions, rare gene variants, copy number variants polymorphisms, or epigenetic modifications and microRNAs regulating gene transcription. In summary, we present results of our studies on obesity risk variants in Czech adults, children and adolescents including those evaluating the influence of selected gene variants on the outcomes of weight management.

MTNR1B Genetic Variability Is Associated with Gestational Diabetes in Czech Women.

The gene MTNR1B encodes a receptor for melatonin. Melatonin receptors are expressed in human ß-cells, which implies that genetic variants might affect glucose tolerance. Meta-analysis confirmed that the rs10830963 shows the most robust association. The aim of the study was to assess the rs10830963 in Czech GDM patients and controls and to study relations between the SNP and biochemical as well as anthropometric characteristics. Our cohort consisted of 880 women; 458 were diagnosed with GDM, and 422 were normoglycemic controls without history of GDM. Despite similar BMI, the GDM group showed higher WHR, waist circumference, abdominal circumference, and total body fat content. The risk allele G was more frequent in the GDM group (38.3 versus 29.4% in controls, OR 1.49 CI95% [1.22; 1.82]; P OR = 0.0001). In spite of higher frequency, the G allele in the GDM group was not associated with any markers of glucose metabolism. In contrast, controls showed significant association of the allele G with FPG and with postchallenge glycemia during the oGTT. Frequency analysis indicates that rs10830963 is involved in gestational diabetes in Czech women. However, the association of the SNP with glucose metabolism, which is obvious in controls, is covert in women who have experienced GDM.

Laparoscopic greater curvature plication in morbidly obese women with type 2 diabetes: effects on glucose homeostasis, postprandial triglyceridemia and selected gut hormones.

BACKGROUND: Laparoscopic greater curvature plication (LGCP) is an emerging bariatric procedure that reduces the gastric volume without implantable devices or gastrectomy. The aim of this study was to explore changes in glucose homeostasis, postprandial triglyceridemia, and meal-stimulated secretion of selected gut hormones [glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), ghrelin, and obestatin] in patients with type 2 diabetes mellitus (T2DM) at 1 and 6 months after the procedure. METHODS: Thirteen morbidly obese T2DM women (mean age, 53.2 ± 8.76 years; body mass index, 40.1 ± 4.59 kg/m2) were prospectively investigated before the LGCP and at 1- and 6-month follow-up. At these time points, all study patients underwent a standardized liquid mixed-meal test, and blood was sampled for assessment of plasma levels of glucose, insulin, C-peptide, triglycerides, GIP, GLP-1, ghrelin, and obestatin. RESULTS: All patients had significant weight loss both at 1 and 6 months after the LGCP (p ≤ 0.002), with mean percent excess weight loss (%EWL) reaching 29.7 ± 2.9% at the 6-month follow-up. Fasting hyperglycemia and hyperinsulinemia improved significantly at 6 months after the LGCP (p < 0.05), with parallel improvement in insulin sensitivity and HbA1c levels (p < 0.0001). Meal-induced glucose plasma levels were significantly lower at 6 months after the LGCP (p < 0.0001), and postprandial triglyceridemia was also ameliorated at the 6-month follow-up (p < 0.001). Postprandial GIP plasma levels were significantly increased both at 1 and 6 months after the LGCP (p < 0.0001), whereas the overall meal-induced GLP-1 response was not significantly changed after the procedure (p > 0.05). Postprandial ghrelin plasma levels decreased at 1 and 6 months after the LGCP (p < 0.0001) with no significant changes in circulating obestatin levels. CONCLUSION: During the initial 6-month postoperative period, LGCP induces significant weight loss and improves the metabolic profile of morbidly obese T2DM patients, while it also decreases circulating postprandial ghrelin levels and increases the meal-induced GIP response.

Steroids and insulin resistance in pregnancy.

Metabolism of glucose during pregnancy reflects the equilibrium between lactogenic hormones stimulating insulin production and counterregulatory hormones inducing insulin resistance. In physiological pregnancies, insulin-mediated glucose uptake is substantially decreased and insulin secretion increased to maintain euglycemia. This common state of peripheral insulin resistance arises also due to steroid spectra changes. In this review article, we have focused on the role of steroid hormones (androgens, estrogens, gestagens, mineralocorticoids, glucocorticoids, as well as secosteroid vitamin D) in the impairment of glucose tolerance in pregnancy and in the pathogenesis of gestational diabetes mellitus. This article is part of a Special Issue entitled 'Pregnancy and Steroids'.

[(TTTTA), polymorphism in the promoter of the CYP11A1 gene in the pathogenesis of polycystic ovary syndrome]. / Promotorový polymorfismus (TTTTA)n genu CYP11A1 v patogenezi syndromu polycystických ovarií.

BACKGROUND: Polycystic ovary syndrome (PCOS) is a common endocrinopathy which is characterized by ovarian androgen excess. PCOS has a strong genetic component but the pathogenetic mechanisms responsible for hyperandrogenemia are still unknown. The CYP11A1 encodes the cholesterol side-chain cleavage enzyme that catalyzes the first and rate-limiting step of steroidogenesis. A promoter polymorphism (TTTTA)n CYP11A1 has been reported to be related to the risk of PCOS but the results were controversial. METHODS AND RESULTS: We determined this polymorphism in a cohort of 256 PCOS and 109 healthy control women. Using two models (dominant model for allele with 4 repeats and dominant model for long alleles, i.e. 7 and more repeats) we did not find either the difference in allele and genotype distribution between PCOS and controls or the influence of polymorphism on serum testosterone and androstendione levels. However, the PCOS carriers of long alleles had lower FSH, total- and LDL-cholesterol compared to the carriers of short alleles (p = 0.007; p = 0.02; p = 0.02, ANOVA). In controls, the non-carriers of allele with 4 repeats had significantly higher DHEA-S (p = 0.02, ANOVA) levels than the carriers of allele with 4 repeats. CONCLUSIONS: Despite of some associations found, it seems that the promoter variability of CYP11A1 does not play a key role in the pathogenesis of PCOS.

[Relation between insulin secretion and action--study of genetic determination]. / Vztah sekrece a pusobení inzulínu--studium genetické determinace.

BACKGROUND: The disposition index represents insulin secretion related to the degree of insulin sensitivity, being constant for given degree of glucose tolerance. The aim of this study is to discern genetic determinants influencing the value of disposition index, e.g. predisposition to glucose intolerance. METHODS AND RESULTS: Two hundred and four non-diabetic subjects with varied glucose tolerance were divided into groups according to the values of disposition index. Glucose and lipid metabolism, anthropometric parameters and family history of type 2 diabetes mellitus (DM2) were examined. The genotype frequency of candidate genes was compared between the groups of individuals within the lowest (Q1) and the highest (Q4) quartiles of the disposition index values. Those groups were not different concerning age and female to male ratio. Fasting and stimulated parameters of glucose metabolism and lipid profile were worse in group Q1 compared to group Q4. Group Q1 is characterized with higher number of individuals with metabolic syndrome and family history of DM2. The examination of candidate genes revealed the differences in genotype frequency of B2AR (rs1042714), PPARA (rs1800206), KCNJ11 (rs5219), and SLC30A8 (rs13266634) between groups Q1 and Q4. CONCLUSIONS: Low value of disposition index is related to the deterioration of glucose tolerance and other signs of metabolic syndrome. It is associated with genes affecting insulin secretion and genes related to energy metabolism and obesity.