Association between genetic variations in MTNR1A and MTNR1B genes and gestational diabetes mellitus in Han Chinese women

Association of rotating night shift work, CLOCK, MTNR1A, MTNR1B genes polymorphisms and their interactions with type 2 diabetes among steelworkers: a case-control study

BACKGROUND

The purpose of this study is to investigate the association of rotating night shift work, CLOCK, MTNR1A, MTNR1B genes polymorphisms and their interactions with type 2 diabetes among steelworkers.

METHODS

A case-control study was conducted in the Tangsteel company in Tangshan, China. The sample sizes of the case group and control group were 251 and 451, respectively. The logistic regression, log-linear model and generalized multifactor dimensionality (GMDR) method were used to investigate the interaction between circadian clock gene, melatonin receptor genes and rotating night shift work on type 2 diabetes among steelworkers. Relative excess risk due to interaction (RERI) and attributable proportions (AP) were used to evaluate additive interactions.

RESULTS

Rotating night shift work, current shift status, duration of night shifts, and average frequency of night shifts were associated with an increased risk of type 2 diabetes after adjustment for confounders. Rs1387153 variants in MTNR1B was found to be associated with an increased risk of type 2 diabetes, which was not found between MTNR1A gene rs2119882 locus, CLOCK gene rs1801260 locus and the risk of type 2 diabetes. The association between rotating night shift work and risk of type 2 diabetes appeared to be modified by MTNR1B gene rs1387153 locus (RERI = 0.98, (95% CI, 0.40-1.55); AP = 0.60, (95% CI, 0.07-1.12)). The interaction between MTNR1A gene rs2119882 locus and CLOCK gene rs1801260 locus was associated with the risk of type 2 diabetes (RERI = 1.07, (95% CI, 0.23-1.91); AP = 0.77, (95% CI, 0.36-1.17)). The complex interaction of the MTNR1A-MTNR1B-CLOCK-rotating night shift work model based on the GMDR methods may increase the risk of type 2 diabetes (P = 0.011).

CONCLUSIONS

Rotating night shift work and rs1387153 variants in MTNR1B were associated with an increased risk of type 2 diabetes among steelworkers. The complex interaction of MTNR1A-MTNR1B-CLOCK-rotating night shift work may increase the risk of type 2 diabetes.

Mouse Models of Gestational Diabetes Mellitus and Its Subtypes: Recent Insights and Pitfalls

Gestational diabetes mellitus (GDM) is currently the most common complication of pregnancy and is defined as a glucose intolerance disorder with recognition during pregnancy. GDM is considered a uniform group of patients in conventional guidelines. In recent years, evidence of the disease's heterogeneity has led to a growing understanding of the value of dividing patients into different subpopulations. Furthermore, in view of the increasing incidence of hyperglycemia outside pregnancy, it is likely that many cases diagnosed as GDM are in fact patients with undiagnosed pre-pregnancy impaired glucose tolerance (IGT). Experimental models contribute significantly to the understanding of the pathogenesis of GDM and numerous animal models have been described in the literature. The aim of this review is to provide an overview of the existing mouse models of GDM, in particular those that have been obtained by genetic manipulation. However, these commonly used models have certain limitations in the study of the pathogenesis of GDM and cannot fully describe the heterogeneous spectrum of this polygenic disease. The polygenic New Zealand obese (NZO) mouse is introduced as a recently emerged model of a subpopulation of GDM. Although this strain lacks conventional GDM, it exhibits prediabetes and an IGT both preconceptionally and during gestation. In addition, it should be emphasized that the choice of an appropriate control strain is of great importance in metabolic studies. The commonly used control strain C57BL/6N, which exhibits IGT during gestation, is discussed in this review as a potential model of GDM.

Melatonin inhibits endometriosis development by disrupting mitochondrial function and regulating tiRNAs

Endometriosis is a benign gynecological disease characterized by abnormal growth of endometrial-like cells outside the uterus. Melatonin, a hormone secreted by the pineal gland, has been shown to have therapeutic effects in various diseases, including endometriosis. However, the underlying molecular mechanisms are yet to be elucidated. The results of this study demonstrated that melatonin and dienogest administration effectively reduced surgically induced endometriotic lesions in a mouse model. Melatonin suppressed proliferation, induced apoptosis, and dysregulated calcium homeostasis in endometriotic cells and primary endometriotic stromal cells. Melatonin also caused mitochondrial dysfunction by permeating through the mitochondrial membrane to disrupt redox homeostasis in the endometriotic epithelial and stromal cells. Furthermore, melatonin affected oxidative phosphorylation systems to decrease ATP production in End1/E6E7 and VK2/E6E7 cells. This was achieved through messenger RNA-mediated downregulation of respiratory complex subunits. Melatonin inhibited the PI3K/AKT and ERK1/2 pathways and the mitochondria-associated membrane axis and further suppressed the migration of endometriotic epithelial and stromal cells. Furthermore, we demonstrated that tiRNA^GluCTC and tiRNA^AspGTC were associated with the proliferation of endometriosis and that melatonin suppressed the expression of these tiRNAs in primary endometriotic stromal cells and lesions in a mouse model. Thus, melatonin can be used as a novel therapeutic agent to manage endometriosis.

Melatonin Receptor 1B Genetic Variants on Susceptibility to Gestational Diabetes Mellitus: A Hospital-Based Case-Control Study in Wuhan, Central China

PURPOSE

The aim of the study was to find out the associations of Melatonin receptor 1B (MTNR1B) genetic variants with gestational diabetes mellitus (GDM) in Wuhan of central China.

PATIENTS AND METHODS

A hospital-based case-control study that included 1679 women was carried out to explore the associations of MTNR1B single nucleotide polymorphisms (SNPs) with GDM risk, which were analyzed through logistic regression analysis by adjusting age, pre-pregnancy BMI and family history of diabetes. Multifactor dimensionality reduction was applied to determine gene-gene interactions between SNPs.

RESULTS

MTNR1B SNPs rs10830962, rs10830963, rs1387153, rs7936247 and rs4753426 were significantly associated with GDM risk (P<0.05). The rs10830962/G, rs10830963/G, rs1387153/T, and rs7936247/T were risk variants, whereas rs4753426/T was protective variant for GDM development. Fasting plasma glucose (FPG) and 1h-plasma glucose (PG) were significantly different among genotypes at rs10830962 and rs10830963, whereas 2h-PG levels were not. Gene-gene interactions were not found among the five SNPs on GDM risk.

CONCLUSION

MTNR1B genetic variants have significant associations but no gene-gene interactions with GDM risk in central Chinese population. Furthermore, MTNR1B SNPs have significant relationships with glycemic traits.

Membrane Melatonin Receptors Activated Cell Signaling in Physiology and Disease

The pineal hormone melatonin has attracted great scientific interest since its discovery in 1958. Despite the enormous number of basic and clinical studies the exact role of melatonin in respect to human physiology remains elusive. In humans, two high-affinity receptors for melatonin, MT1 and MT2, belonging to the family of G protein-coupled receptors (GPCRs) have been cloned and identified. The two receptor types activate Gi proteins and MT2 couples additionally to Gq proteins to modulate intracellular events. The individual effects of MT1 and MT2 receptor activation in a variety of cells are complemented by their ability to form homo- and heterodimers, the functional relevance of which is yet to be confirmed. Recently, several melatonin receptor genetic polymorphisms were discovered and implicated in pathology-for instance in type 2 diabetes, autoimmune disease, and cancer. The circadian patterns of melatonin secretion, its pleiotropic effects depending on cell type and condition, and the already demonstrated cross-talks of melatonin receptors with other signal transduction pathways further contribute to the perplexity of research on the role of the pineal hormone in humans. In this review we try to summarize the current knowledge on the membrane melatonin receptor activated cell signaling in physiology and pathology and their relevance to certain disease conditions including cancer.

Identification of Key Regions Mediating Human Melatonin Type 1 Receptor Functional Selectivity Revealed by Natural Variants

Melatonin is a hormone mainly produced by the pineal gland and MT₁ is one of the two G protein-coupled receptors (GPCRs) mediating its action. Despite an increasing number of available GPCR crystal structures, the molecular mechanism of activation of a large number of receptors, including MT₁, remains poorly understood. The purpose of this study is to elucidate the structural elements involved in the process of MT₁'s activation using naturally occurring variants affecting its function. Thirty-six nonsynonymous variants, including 34 rare ones, were identified in MTNR1A (encoding MT₁) from a cohort of 8687 individuals and their signaling profiles were characterized using Bioluminescence Resonance Energy Transfer-based sensors probing 11 different signaling pathways. Computational analysis of the experimental data allowed us to group the variants in clusters according to their signaling profiles and to analyze the position of each variant in the context of the three-dimensional structure of MT₁ to link functional selectivity to structure. MT₁ variant signaling profiles revealed three clusters characterized by (1) wild-type-like variants, (2) variants with selective defect of βarrestin-2 recruitment, and (3) severely defective variants on all pathways. Our structural analysis allows us to identify important regions for βarrestin-2 recruitment as well as for Gα12 and Gα15 activation. In addition to identifying MT₁ domains differentially controlling the activation of the various signaling effectors, this study illustrates how natural variants can be used as tools to study the molecular mechanisms of receptor activation.

Association between melatonin receptor gene polymorphisms and polycystic ovarian syndrome: a systematic review and meta-analysis

BACKGROUND

Polycystic ovarian syndrome (PCOS) is a kind of common gynecological endocrine disorder. And the mutations of melatonin receptor (MTNR) genes are related to the occurrence of PCOS. But previous researches have shown opposite results. So, the object of our systematic review and meta-analysis is to investigate the relationship between MTNR 1A/B polymorphisms and PCOS.

METHODS

PubMed, Embase, Ovid, the Cochrane Library, Web of Science and three Chinese databases (VIP, CNKI and Wanfang) were used to retrieve eligible articles published between January 1980 and February 2020. And we used the odds ratio (OR) and its 95% confidence interval (CI) to investigate the strength of the association by six genetic models, allelic, codominant (homozygous and heterozygous), dominant, recessive and superdominant models. Review Manager 5.3, IBM SPSS statistics 25 and Stata MP 16.0 software were used to do this meta-analysis.

RESULTS

Our meta-analysis involved 2553 PCOS patients and 3152 controls, for two single nucleotide polymorphisms (rs10830963 C> G in MTNR1B and rs2119882 T> C in MTNR1A) and significant associations were found in some genetic models of these single nucleotide polymorphisms (SNPs). For rs10830963, strongly significant was found in the heterozygote model (GC vs. CC, P=0.02). Additionally, a slight trend was detected in the allelic (G vs. C), homozygote (GG vs. CC) and dominant (GG+GC vs. CC) model of rs10830963 (P=0.05). And after further sensitivity analysis, a study with high heterogeneity was removed. In the allelic (P=0.000), homozygote (P=0.001), dominant (P=0.000) and recessive (GG vs. GC+CC, P=0.001) model, strong associations between rs10830963 and PCOS were found. Moreover, for rs2119882, five genetic models, allelic (C vs. T, P=0.000), codominant (the homozygote (CC vs. TT, P=0.000) and heterozygote model (CT vs. TT, P=0.02), dominant (CC + CT vs. TT, P=0.03) and recessive model (CC vs. CT + TT, P=0.000) showed significant statistical associations with PCOS.

CONCLUSION

MTNR1B rs10830963 and MTNR1B rs2119882 polymorphisms are associated with PCOS risk. However, the above conclusions still require being confirmed by much larger multi-ethnic studies.

Association of Common Genetic Risk Variants With Gestational Diabetes Mellitus and Their Role in GDM Prediction

OBJECTIVE

We aimed to explore the associations between common genetic risk variants with gestational diabetes mellitus (GDM) risk in Russian women and to assess their utility in the identification of GDM cases.

METHODS

We conducted a case-control study including 1,142 pregnant women (688 GDM cases and 454 controls) enrolled at Almazov National Medical Research Centre. The International Association of Diabetes and Pregnancy Study Groups criteria were used to diagnose GDM. A total of 11 single- nucleotide polymorphisms (SNPs), including those in HKDC1 (rs10762264), GCK (rs1799884), MTNR1B (rs10830963 and rs1387153), TCF7L2 (rs7903146 and rs12255372), KCNJ11 (rs5219), IGF2BP2 (rs4402960), IRS1 (rs1801278), FTO (rs9939609), and CDKAL1 (rs7754840) were genotyped using Taqman assays. A logistic regression model was used to calculate odds ratios (ORs) and their confidence intervals (CIs). A simple-count genetic risk score (GRS) was calculated using 6 SNPs. The area under the receiver operating characteristic curve (c-statistic) was calculated for the logistic regression model predicting the risk of GDM using clinical covariates, SNPs that had shown a significant association with GDM in our study, GRS, and their combinations.

RESULTS

Two variants in MTNR1B (rs1387153 and rs10830963) demonstrated a significant association with an increased risk of GDM. The association remained significant after adjustment for age, pre-gestational BMI, arterial hypertension, GDM in history, impaired glucose tolerance, polycystic ovary syndrome, family history of diabetes, and parity (P = 0.001 and P < 0.001, respectively). After being conditioned by each other, the effect of rs1387153 on GDM predisposition weakened while the effect of rs10830963 remained significant (P = 0.004). The risk of GDM was predicted by clinical variables (c-statistic 0.712, 95 % CI: 0.675 - 0.749), and the accuracy of prediction was modestly improved by adding GRS to the model (0.719, 95 % CI 0.682 - 0.755), and more by adding only rs10830963 (0.729, 95 % CI 0.693 - 0.764).

CONCLUSION

Among 11 SNPs associated with T2D and/or GDM in other populations, we confirmed significant association with GDM for two variants in MTNR1B in Russian women. However, these variants showed limited value in the identification of GDM cases.

Genetic Studies of Gestational Diabetes and Glucose Metabolism in Pregnancy

PURPOSE OF REVIEW

In this review, we summarize studies investigating genetics of gestational diabetes mellitus (GDM) and glucose metabolism in pregnancy. We describe these studies in the context of the larger body of literature on type 2 diabetes (T2D) and glycemic trait genomics.

RECENT FINDINGS

We reviewed 23 genetic association studies for GDM and performed a meta-analysis, which revealed variants at eight T2D loci significantly associated with GDM after the Bonferroni correction. These studies suggest that GDM and T2D share a number of genetic risk loci. Only two unbiased genome-wide association studies (GWASs) have successfully revealed genetic associations for GDM and related glycemic traits in pregnancy. A GWAS for GDM in Korean women identified two loci (near CDKAL1 and MTNR1B) known to be associated with T2D, though the association of the MTNR1B locus with GDM appears to be stronger than that for T2D. A multi-ethnic GWAS for glycemic traits in pregnancy identified two novel loci (near HKDC1 and BACE2) which appear to be associated with post-load glucose and fasting c-peptide specifically in pregnant women. There are ongoing efforts to use this genetic information, in the form of polygenic scores, to predict risk of GDM and postpartum T2D. The body of literature examining genetic associations with GDM is limited, especially when compared to the available literature on T2D and glycemic trait genomics. Additional genetic discovery for glucose metabolism in pregnant women will require larger pregnancy cohorts and international collaborative efforts. Studies on the clinical implications of these findings are also warranted.

A functional polymorphism rs10830963 in melatonin receptor 1B associated with the risk of gestational diabetes mellitus

The melatonin receptor 1B (MTNR1B) polymorphism rs10830963 C>G has been reported to be associated with the risk of gestational diabetes mellitus (GDM) with inconsistent results. To clarify the effect of the polymorphism on the risk of GDM, a meta-analysis therefore was performed. Pooled OR with its corresponding 95%CI was used to estimate the strength of the association. Totally 14 eligible studies with a number of 5033 GDM patients and 5614 controls were included in this meta-analysis. Results indicated that the variant G allele was significantly associated with an increased GDM risk (CG vs. CC: OR = 1.25, 95% CI = 1.11−1.40, P < 0.001; GG vs. CC: OR = 1.78, 95% CI = 1.45−2.19, P < 0.001; G vs. C: OR = 1.33, 95% CI = 1.21−1.47, P < 0.001). In the stratified analysis by ethnicity, similar results were found in Asians (CG vs. CC: OR = 1.15, 95%CI = 1.02−1.28, P = 0.020; GG vs. CC: OR = 1.52, 95% CI = 1.23−1.89, P < 0.001; G vs. C: OR = 1.23, 95% CI = 1.10−1.37, P < 0.001) and in Caucasians (CG vs. CC: OR = 1.40, 95% CI = 1.16−1.70, P < 0.001; GG vs. CC: OR = 2.21, 95% CI = 1.54−3.17, P < 0.001; G vs. C: OR = 1.47, 95% CI = 1.24−1.73, P < 0.001). FPRP and TSA analyses confirmed findings support that the rs10830963 G allele increases the risk of GDM, and further functional experimental studies are warranted to explore and clarify the potential mechanism.

Genetic susceptibility, lifestyle intervention and glycemic changes among women with prior gestational diabetes

AIMS

Women with prior gestational diabetes mellitus (GDM) or high genetic susceptibility are prone to development of type 2 diabetes. We examined whether a lifestyle intervention modified the genetic effect on changes in glycemic markers among women with prior GDM.

RESEARCH DESIGN AND METHODS

This study included 560 women with prior GDM from a randomized controlled trial, the Tianjin Gestational Diabetes Mellitus Prevention Program, who were assigned into an intervention arm (improved physical activity and healthy dietary intakes) or a control arm. We assessed associations of GDM related genetic variants in/near the CDKAL1 (rs7754840) and MTNR1B (rs10830962) genes with changes in fasting levels of glucose and insulin, β-cell function (HOMA-B) and insulin resistance (HOMA-IR) at 1 year and 2 years after the baseline.

RESULTS

We found significant interactions between CDKAL1 variant rs7754840 and lifestyle intervention on changes in fasting insulin and HOMA-IR at 1 year (P for interactions = 0.008 and 0.006, respectively). The GDM-increasing C allele was associated with a 0.07-unit greater increase in fasting insulin (P = 0.048) and HOMA-IR (P = 0.045) in the control group, while opposite-directional associations were observed in the intervention group; women with the C allele seemed to decrease more in these glycemic markers than the non-C-carriers (both P ≤ 0.06). The interactions between the CDKAL1 genetic variant and lifestyle intervention on changes in fasting insulin (P = 0.035) and HOMA-IR (P = 0.024) remained significant over the 2-year period, even though the effects of lifestyle intervention were attenuated at 2-year. The MTNR1B variant rs10830962 did not show interaction with lifestyle intervention on changes in the glycemic markers.

CONCLUSIONS

Healthy lifestyle intervention may be beneficial for women with the GDM predisposing CDKAL1 genetic variant in improvement of insulin resistance.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT01554358. URL OF REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT01554358.

MTNR1B genetic polymorphisms as risk factors for gestational diabetes mellitus: a case-control study in a single tertiary care center

BACKGROUND

Gestational diabetes mellitus (GDM) is a metabolic disease in pregnancy that causes carbohydrate intolerance and hyper-glycemia. Genome-wide association studies and meta-analyses have found that the single nucleotide polymorphisms (SNPs) rs1387153 and rs10830963 of the melatonin receptor 1B ( MTNR1B) gene are associated with GDM. No studies on the MTNR1B gene effect on GDM have been performed in Saudis, other Arabs, or other Middle Eastern populations.

OBJECTIVES

Investigate the association of genotype or allele frequencies of the two SNPs with GDM and with clinical parameters related to GDM.

DESIGN

Case-control study.

SETTINGS

Tertiary care center, Riyadh.

PATIENTS AND METHODS

We recruited 400 pregnant Saudi women ages 18-45 years (200 were diagnosed with GDM, and 200 were healthy controls). Biochemical assays were performed, and rs1387153 and rs10830963 polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism analysis and real-time polymerase chain reaction with TaqMan genotyping.

MAIN OUTCOME MEASURES

The association of MTNR1B gene (rs1387153 and rs10830963 polymorphisms) with GDM and with biochemical parameters related to GDM.

SAMPLE SIZE

200 GDM cases and 200 non-GDM controls.

RESULTS

Differences in allele frequencies for GDM vs non-GMD were statistically significant or nearly significant for both SNPs after adjustment for age and body mass index. In a logistic regression analysis, genotype TT was positively associated with post-prandial blood glucose (P=.018), but other associations were not statistically significant.

CONCLUSION

The odds ratios for the associations between the rs1387153 and rs10830963 SNPs and GDM exceeded 1.5-fold, which is higher than typically reported for diseases with complex genetic background. These effect sizes for GDM suggest pregnancy-specific factors related to the MTNR1B risk genotypes.

LIMITATIONS

Only two SNPs were studied.

CONFLICT OF INTEREST

None.

New insights into the function of melatonin and its role in metabolic disturbances

INTRODUCTION

Melatonin is a pineal hormone that has acquired several unique modes of regulating the physiological effects in mammals due to its characteristic phylogenetic history. While melatonin exhibits immediate nocturnal effects, it also has next-day prospective effects that take place in the absence of this hormone. Besides that, the daily repetition and the annual variation in the duration of its synthesis determine its circadian and seasonal effects that characterize melatonin as a chronobiotic, a molecule that encodes time to the internal environment. Additionally, it presents transgenerational effects that are important for fetal programming, leading to a balanced energy metabolism in the adult life.

AREAS COVERED

Physiology, pathophysiology and therapeutic value of melatonin in metabolism and metabolic disorders.

EXPERT OPINION

The typical mechanisms of action of melatonin (immediate, prospective, chronobiotic and transgenerational) should be considered to adequately understand its physiological effects on the regulation of metabolism in humans and, as a result, to understand the metabolic pathophysiological consequences caused by its synthesis and/or signaling disturbances. That points to the importance of a broader understanding of melatonin actions, besides the classical endocrinological point of view, that would allow the clinician/research to proper interpret its role in health maintenance.

Heterogeneous impact of type 2 diabetes mellitus-related genetic variants on gestational glycemic traits: review and future research needs

Gestational glucose homeostasis influences mother's metabolic health, pregnancy outcomes, fetal development and offspring growth. To understand the genetic roles in pregnant glucose metabolism and genetic predisposition for gestational diabetes (GDM), we reviewed the recent literature up to Jan, 2018 and evaluated the influence of T2DM-related genetic variants on gestational glycemic traits and glucose tolerance. A total of 140 variants of 89 genes were integrated. Their associations with glycemic traits in and outside pregnancy were compared. The genetic circumstances underlying glucose metabolism exhibit a similarity between pregnant and non-pregnant populations. While, not all of the T2DM-associated genetic variants are related to pregnant glucose tolerance, such as genes involved in fasting insulin/C-peptide regulation. Some genetic variants may have distinct effects on gestational glucose homeostasis. And certain genes may be particularly involved in this process via specific mechanisms, such as HKDC1, MTNR1B, BACE2, genes encoding cell cycle regulators, adipocyte regulators, inflammatory factors and hepatic factors related to gestational glucose sensing and insulin signaling. However, it is currently difficult to evaluate these associations with quantitative synthesis due to inadequate data, different analytical methods, varied measurements for glycemic traits, controversies in diagnosis of GDM, and unknown ethnicity- and/or sex-related influences on pregnant maternal metabolism. In conclusion, different genetic associations with glycemic traits may exist between pregnant and non-pregnant conditions. Comprehensive research on specific genetic regulation in gestation is necessary.

Association of rs10830962 polymorphism with gestational diabetes mellitus risk in a Chinese population

To date, only three polymorphisms (rs10830962, rs7754840 and rs1470579) are included in the genome-wide association study Catalog (www.ebi.ac.uk/gwas). However, the available evidence is limited in pregnant Chinese women. We aimed to explore the associations of three polymorphisms (rs10830962, rs7754840 and rs1470579) with GDM risk in a Chinese population. We conducted a case-control study (964 GDM cases and 1,021 controls) to evaluate the associations of these polymorphisms with GDM risk. A logistic regression model was used to calculate odds ratios (ORs) and their confidence intervals (CIs). After adjustment for age, prepregnancy BMI, parity, abnormal pregnancy history and family history of diabetes, the minor allele of rs10830962 (C > G) demonstrated a significant association with an increased risk of GDM (OR = 1.16, 95% CI = 1.02–1.31, P = 0.029 in the additive model). However, no significant association was observed between the other two polymorphisms and GDM. Subsequent functional annotation shows that rs10830962 is located in the regulatory elements of pancreatic islets, alters the binding affinity of motifs and regulates SNORA8 expression. Our findings demonstrate that rs10830962 is associated with an increased risk of GDM in the Chinese population. Further functional characterization is warranted to uncover the mechanism of the genotype-phenotype association.

Replication of previous genome-wide association studies of HKDC1, BACE2, SLC16A11 and TMEM163 SNPs in a gestational diabetes mellitus case-control sample from Han Chinese population

Background: Four novel glucose metabolism risk loci (HKDC1 rs4746822, BACE2 rs6517656, SLC16A11 rs13342232 and TMEM163 rs998451) were identified in recent genome-wide association studies (GWAS) of Afro-Caribbean, European, Hispanic, Thai, Mexican, Latin American and Indian populations. None of the abovementioned SNPs has been reported in a Han Chinese population. Aim: To replicate the relationships between HKDC1 rs4746822, BACE2 rs6517656, SLC16A11 rs13342232 and TMEM163 rs998451 with gestational diabetes mellitus (GDM) in a Han Chinese population. Methods: This was a case-control study which enrolled 334 pregnant women with GDM and 367 pregnant women with normal glucose tolerance. The linear regression and logistic regression were used to estimate the association between SNPs with the risk of GDM, HOMA-IR and fasting insulin levels. The fasting insulin concentration and HOMA-IR were log10 transformed before analysis. Results: No significant differences in the alleles and genotypes of SLC16A11 rs13342232, HKDC1 rs4746822 and BACE2 rs6517656 were observed between cases and controls. After adjusting the weekly BMI growth, pre-pregnancy BMI and maternal age, under the additive model, SLC16A11 rs13342232 was associated with log₁₀fasting serum insulin (Beta=0.046, p=0.016), log₁₀HOMA-IR level (Beta=0.061, p=0.003) and fasting plasma glucose level (Beta=0.164, p=0.011); HKDC1 rs4746822 was associated with OGTT 2-hr plasma glucose level (Beta=0.239, p=0.016); and BACE2 rs6517656 was associated with log₁₀fasting serum insulin (Beta=-0.053, p=0.044) and log₁₀HOMA-IR level (Beta=-0.060, p=0.048). After correction for multiple testing, the associations of SLC16A11 and HKDC1 with glucose metabolism remained statistically significant. The A allele of TMEM163 rs998451 was not detected in this population. Conclusion: HKDC1 rs4746822, BACE2 rs6517656 and SLC16A11 rs13342232 are associated with glucose metabolism in pregnant women of Han Chinese.

Melatonin Signaling a Key Regulator of Glucose Homeostasis and Energy Metabolism

Melatonin, a hormone synthesized by both the pineal gland and retina, functions as an important modulator of a number of physiological functions. In addition to its rather well-established roles in the regulation of circadian rhythms, sleep, and reproduction, melatonin has also been identified as an important regulator of glucose metabolism. Recent genomic studies have also shown that disruption of melatonin receptors signaling may contribute to the pathogenesis of type 2 diabetes, although the exact mechanisms underlying its action remain unclear. Additionally, a large number of animal studies have highlighted a role for melatonin in the regulation of both glucose metabolism and energy balance. This review summarizes the current knowledge on the role that melatonin and its associated receptors play in the regulation of metabolism.

Ethnic Disparities in Gestational Diabetes

PURPOSE OF REVIEW

Ethnicity has long been described as a major risk factor for the development of gestational diabetes mellitus (GDM), and it is widely recognised that women from ethnicities other than Europids are at higher risk of developing GDM. There are also described differences between ethnicities in key GDM pregnancy outcomes. This review describes some of the factors that relate to the ethnic disparities in GDM.

RECENT FINDINGS

The global prevalence of GDM has been steadily increasing and estimated to be 16.2% from the International Diabetes Federation extrapolation. Reported prevalence rates may understate the true prevalence, due to factors of access and attitudes to GDM diagnosis and screening in low resource settings for foreign-born women and indigenous populations. Other factors may relate to genes associated with specific ethnicities, obesity, body composition and gestational weight gain. Various factors such as access to screening, body composition, genetics and gestational weight gain may result in ethnic disparities in the prevalence and outcomes of GDM.

Early second trimester maternal serum markers in the prediction of gestational diabetes mellitus

AIMS/INTRODUCTION

To determine whether maternal serum markers in the early second trimester are useful for prediction of gestational diabetes mellitus (GDM).

MATERIALS AND METHODS

A total of 876 singleton pregnancies were recruited in the present study. Blood samples were collected during 16-20 gestational weeks. GDM women were diagnosed by an oral glucose tolerance test during 24-28 gestational weeks. A total of 56 women with GDM and 73 healthy pregnant women were selected. Maternal serum concentrations of placental protein 13 (PP13), pentraxin 3 (PTX3), soluble fms-like tyrosine kinase-1 (sFlt-1), myostatin and follistatin (FST) were detected at 16-20 weeks' gestation. All of these markers concentrations were expressed as multiples of the medians. The Mann-Whitney U-test was used for comparison of the multiples of the medians of different concentrations of these five serum markers between the GDM group and the control group. Receiver operating characteristic curve analysis was applied to assess the sensitivity and specificity of significant serum markers from a Mann-Whitney U-test comparison.

RESULTS

Compared with healthy pregnancies, the serum levels of PP13, PTX3, sFlt-1, myostatin and FST in the early second trimester were significantly increased in patients who had developed GDM late. In screening for GDM by PP13, PTX3, sFlt-1, myostatin and FST, the detection rates were 92.3, 94.9, 94.9, 92.5 and 92.3%, respectively at 80% specificity. PTX3 and sFlt-1 were the most sensitive markers.

CONCLUSIONS

Maternal serum markers including PP13, PTX3, sFlt-1, myostatin and FST increase in the early second trimester of women with GDM. These five markers, especially PTX3 and sFlt-1, could have the value of prediction for those patients who would develop GDM in the late second trimester.

Association Between a Melatonin Receptor 1B Genetic Polymorphism and Its Protein Expression in Gestational Diabetes Mellitus

AIMS

This study was conducted to investigate the relationship between a genetic polymorphism and the expression of melatonin receptor 1B (MTNR1B) in the placenta of Han Chinese women with gestational diabetes mellitus (GDM).

METHODS

In this study, 215 patients with GDM and 243 healthy controls were genotyped using direct sequencing for the MTNR1B single-nucleotide polymorphism rs10830963. The expression of MTNR1B in placenta was detected by immunohistochemistry and Western blotting. The association of rs10830963 with the expression of MTNR1B, plasma glucose, and insulin levels as well as blood lipid levels was investigated.

RESULTS

The genotype and allele frequencies of rs10830963 were significantly different between women with GDM and controls (P < .05). Fasting blood glucose, fasting insulin, and homeostasis model assessment for insulin resistance in women with GDM with the GG and GC genotypes were significantly higher than those with the CC genotype (P < .05). The expression level of MTNR1B in placenta was significantly higher in the GDM group than in the control group (P < .05). The expression of MTNR1B was significantly higher in all participants with the GG and GC genotypes (1.31 [0.74]) than in pregnant women with the CC genotype (0.92 [0.52], P < .05).

CONCLUSIONS

The genetic polymorphism rs10830963 in MTNR1B and its protein expression levels in placenta are associated with an increased risk of developing GDM. Furthermore, rs10830963 may tag a molecular mechanism leading to insulin resistance in Han Chinese women with GDM.

Nocturnal activation of melatonin receptor type 1 signaling modulates diurnal insulin sensitivity via regulation of PI3K activity

Recent genetic studies have highlighted the potential involvement of melatonin receptor 1 (MT₁ ) and melatonin receptor 2 (MT₂ ) in the pathogenesis of type 2 diabetes. Here, we report that mice lacking MT₁ (MT₁ KO) tend to accumulate more fat mass than WT mice and exhibit marked systemic insulin resistance. Additional experiments revealed that the main insulin signaling pathway affected by the loss of MT₁ was the activation of phosphatidylinositol-3-kinase (PI3K). Transcripts of both catalytic and regulatory subunits of PI3K were strongly downregulated within MT₁ KO mice. Moreover, the suppression of nocturnal melatonin levels within WT mice, by exposing mice to constant light, resulted in impaired PI3K activity and insulin resistance during the day, similar to what was observed in MT₁ KO mice. Inversely, administration of melatonin to WT mice exposed to constant light was sufficient and necessary to restore insulin-mediated PI3K activity and insulin sensitivity. Hence, our data demonstrate that the activation of MT₁ signaling at night modulates insulin sensitivity during the day via the regulation of the PI3K transcription and activity. Lastly, we provide evidence that decreased expression of MTNR1A (MT₁ ) in the liver of diabetic individuals is associated with poorly controlled diabetes.

Physiologic Interpretation of GWAS Signals for Type 2 Diabetes

This chapter reviews both statistical and physiologic issues related to the pathophysiologic effects of genetic variation in the context of type 2 diabetes. The goal is to review current methodologies used to analyze disease-related quantitative traits for those who do not have extensive quantitative and physiologic background, as an attempt to bridge that gap. We leverage mathematical modeling to illustrate the strengths and weaknesses of different approaches and attempt to reinforce with real data analysis. Topics reviewed include phenotype selection, phenotype specificity, multiple variant analysis via the genetic risk score, and consideration of multiple disease-related phenotypes. Type 2 diabetes is used as the example, not only because of the extensive existing knowledge at the genetic, physiologic, clinical, and epidemiologic levels, but also because type 2 diabetes has been at the forefront of complex disease genetics, with many examples to draw from.

MTNR1A and MTNR1B gene polymorphisms in women with gestational diabetes

Gestational diabetes mellitus (GDM) is glucose intolerance detected during pregnancy. The MTNR1B gene is the genetic locus associated with type 2 diabetes, that may affect insulin secretion and pancreatic glucose sensing. In this study, we examined the association between MTNR1A (rs2119882) and MTNR1B (rs10830963, rs4753426) gene polymorphisms and the risk of GDM. According to the results of their oral glucose tolerance test (OGTT), the women were divided into two groups: 204 pregnant women with GDM and 207 pregnant women with normal glucose tolerance (NGT). There were no statistically significant differences in the distribution of MTNR1A rs2119882 and MTNR1B rs4753426 genotypes and alleles between women with GDM and healthy pregnant women. With regard to the MTNR1B rs10830963 polymorphism, we observed a statistically significant prevalence of GG and CG genotypes and the G allele among pregnant women with GDM (GG + CG vs CC, OR 1.50, 95% CI 1.02-2.22, p = 0.04; G vs C, OR 1.43, 95% CI 1.07-1.90, p = 0.016). In a multivariate logistic regression analysis, a higher number of MTNR1B rs10830963 G alleles was an independent significant predictor of a higher risk of GDM. The results of our study indicate that MTNR1B rs10830963 polymorphism is associated with GDM susceptibility, and women with a higher number of G alleles have an increased risk of GDM development.

Polymorphisms in Four Genes (KCNQ1 rs151290, KLF14 rs972283, GCKR rs780094 and MTNR1B rs10830963) and Their Correlation with Type 2 Diabetes Mellitus in Han Chinese in Henan Province, China

Genetic variants at KCNQ1 rs151290, KLF14 rs972283, GCKR rs780094 and MTNR1B rs10830963 have been associated with type 2 diabetes mellitus (T2DM), but the results are contradictory in Chinese populations. The aim of the present study was to investigate the association of these four SNPs with T2DM in a large population of Han Chinese at Henan province, China. Seven-hundred-thirty-six patients with T2DM (cases) and Seven-hundred-sixty-eight healthy glucose-tolerant controls were genotyped for KCNQ1 rs151290, KLF14 rs972283, GCKR rs780094 and MTNR1B rs10830963. The association of genetic variants in these four genes with T2DM was analyzed using multivariate logistic regression. Genotypes and allele distributions of KCNQ1 rs151290 were significantly different between the cases and controls (p < 0.05). The AC and CC genotypes and the combined AC + CC genotype of rs151290 in KCNQ1 were associated with increases risk of T2DM before (OR = 1.482, 95% CI = 1.062–2.069; p = 0.021; OR = 1.544, 95% CI = 1.097–2.172, p = 0.013; and OR = 1.509, 95% CI = 1.097–2.077, p = 0.011, respectively) and after (OR = 1.539, 95% CI = 1.015–2.332, p = 0.042; OR = 1.641, 95% CI = 1.070–2.516, p = 0.023; and OR = 1.582, 95% CI = 1.061–2.358, p = 0.024; respectively) adjustment for sex, age, anthropometric measurements, biochemical indexes, smoking and alcohol consumption. Consistent with results of genotype analysis, the C allele of rs151290 in KCNQ1 was also associated with increased risk of T2DM (OR = 1.166, 95% CI = 1.004–1.355, p = 0.045). No associations between genetic variants of KLF14 rs972283, GCKR rs780094 or MTNR1B rs10830963 and T2DM were detected. The AC and CC genotypes and the C allele of rs151290 in KCNQ1 may be risk factors for T2DM in Han Chinese in Henan province.

Novel Nonsense Mutation in the NLRP7 Gene Associated with Recurrent Hydatidiform Mole

AIM

This study aimed to clarify the genetic and epigenetic features of recurrent hydatidiform mole (RHM) in Japanese patients.

METHODS

Four Japanese isolated RHM cases were analyzed using whole-exome sequencing. Villi from RHMs were collected by laser microdissection for genotyping and DNA methylation assay of differentially methylated regions (DMRs). Single nucleotide polymorphisms of PEG3 and H19 DMRs were used to confirm the parental origin of the variants.

RESULTS

A novel homozygous nonsense mutation in NLRP7 (c.584G>A; p.W195X) was identified in 1 patient. Genotyping of one of her molar tissue revealed that it was biparental but not androgenetic in origin. Despite the fact that the RHM is biparental, maternally methylated DMRs of PEG3, SNRPN and PEG10 showed complete loss of DNA methylation. A paternally methylated DMR of H19 retained normal methylation.

CONCLUSIONS

This is the first Japanese case of RHM with a novel homozygous nonsense NLRP7 mutation and a specific loss of maternal DNA methylation of DMRs. Notably, the mutation was identified in an isolated case of an ethnic background that has not previously been studied in this context. Our data underscore the involvement of NLRP7 in RHM pathophysiology and confirm that DNA methylation of specific regions is critical.

Relationship between melatonin receptor 1B (rs10830963 and rs1387153) with gestational diabetes mellitus: a case-control study and meta-analysis

PURPOSE

Variants rs10830963 (C/G) and rs1387153 (C/T) in MTNR1B have been shown with an increased risk of developing type 2 diabetes and gestational diabetes mellitus. However, the results are still controversial, and evidence was not satisfied. Hence, a case-control study and a further meta-analysis will be performed in this study.

METHODS

We recruited 674 GDM patients and 690 controls from Jan 2010 and Jan 2014. The SNPs were genotyped by ABI TaqMan SNP Genotyping Assays. MTNR1B rs10830963 and rs1387153 single nucleotide polymorphisms (SNPs) were performed for association analysis. Then a systematic search of all relevant studies was conducted. A meta-analysis was performed to prove the relationship between melatonin receptor 1B (rs10830963 and rs1387153) with GDM.

RESULTS

The case-control study presented that G allele of the rs10830963 and T allele of rs1387153 were significantly associated with increased risk of GDM. The further meta-analysis included other five studies showed that the frequency of MTNR1B rs10830963 G allele and rs1387153 T allele are higher in GDM patients.

CONCLUSION

The case-control study proved that the risk allele (G allele) of rs10830963 and (T allele) of rs1387153 lead to a higher risk for GDM. The further meta-analysis provides additional evidence supporting the above results. Due to the limited data currently available in different race population, further studies with large sample sizes are required.

Relationship between melatonin receptor 1B and insulin receptor substrate 1 polymorphisms with gestational diabetes mellitus: a systematic review and meta-analysis

Studies have investigated the relationship between genetic variants and risk of gestational diabetes mellitus (GDM). However, the results remain inconclusive. The aim of this study was to investigate the association of rs10830963 and rs1387153 variants in melatonin receptor 1B (MTNR1B) and rs1801278 variant in insulin receptor substrate 1 (IRS1) with GDM susceptibility. Electronic database of PubMed, Medline, Embase, and CNKI (China National Knowledge Infrastructure) were searched for relevant studies between 2005 and 2014. The odds ratio (OR) with its 95% confidence interval (CI) were employed to estimate the association. Total ten case-control studies, including 3428 GDM cases and 4637 healthy controls, met the inclusion criteria. Our results showed a significant association between the three genetic variants and GDM risk, rs10830963 with a P-value less than 0.0001, rs1387153 with a P-value of 0.0002, and rs1801278 with a P-value of 0.001. Furthermore, all the genetic models in these three polymorphisms were associated with increased risks of GDM as well (P< = 0.009). In conclusion, our study found that the genetic polymorphisms rs10830963 and rs1387153 in MTNR1B and rs1801278 in IRS1 were associated with an increased risk of developing GDM. However, further studies with gene-gene and gene-environmental interactions should be considered.

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 β-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.

Genetic variation in MTNR1B is associated with gestational diabetes mellitus and contributes only to the absolute level of beta cell compensation in Mexican Americans

AIMS/HYPOTHESIS

MTNR1B is a type 2 diabetes susceptibility locus associated with cross-sectional measures of insulin secretion. We hypothesised that variation in MTNR1B contributes to the absolute level of a diabetes-related trait, temporal rate of change in that trait, or both.

METHODS

We tested rs10830963 for association with cross-sectional diabetes-related traits in up to 1,383 individuals or with rate of change in the same phenotypes over a 3-5 year follow-up in up to 374 individuals from the family-based BetaGene study of Mexican Americans.

RESULTS

rs10830963 was associated cross-sectionally with fasting glucose (p = 0.0069), acute insulin response (AIR; p = 0.0013), disposition index (p = 0.00078), glucose effectiveness (p = 0.018) and gestational diabetes mellitus (OR 1.48; p = 0.012), but not with OGTT 30 min Δinsulin (the difference between the 30 min and fasting plasma insulin concentration) or 30 min insulin-based disposition index. rs10830963 was also associated with rate of change in fasting glucose (p = 0.043), OGTT 30 min Δinsulin (p = 0.01) and AIR (p = 0.037). There was no evidence for an association with the rate of change in beta cell compensation for insulin resistance.

CONCLUSIONS/INTERPRETATION

We conclude that variation in MTNR1B contributes to the absolute level of insulin secretion but not to differences in the temporal rate of change in insulin secretion. The observed association with the rate of change in insulin secretion reflects the natural physiological response to changes in underlying insulin sensitivity and is not a direct effect of the variant.