GCK and HNF1A mutations in Canadian families with maturity onset diabetes of the young (MODY)

Maturity onset diabetes of the young (MODY) is a genetically heterogeneous form of type 2 diabetes that is characterized by autosomal dominant inheritance, onset in early adulthood and a primary defect in insulin secretion. Mutations in at least six genes have been shown to underlie MODY, including mutations in GCK (encoding glucokinase, also called MODY2) and mutations in HNF1A (encoding hepatocyte nuclear factor-1alpha, also called MODY3). We sequenced genomic DNA from probands of seven Canadian MODY families. In four probands, we detected four novel GCK mutations, namely IVS2-7G>A, G72R, T206R and S263P. In three other probands, we detected three HNF1A mutations, of which two were novel, namely 1051delCA and Q250X, and one had been previously reported, namely R131Q. The novel mutations expand the spectrum of MODY mutations. In addition, knowledge of the specific defect can be used to pre-symptomatically identify family members at risk for developing MODY.     

Mutations in the genes encoding the transcription factors hepatocyte nuclear factor 1 alpha (HNF1A) and 4 alpha (HNF4A) in maturity-onset diabetes of the young

Maturity-onset diabetes of the young (MODY) is a monogenic form of diabetes mellitus characterized by autosomal dominant inheritance, early age of onset (often <25 years of age), and pancreatic beta-cell dysfunction. MODY is both clinically and genetically heterogeneous, with six different genes identified to date; glucokinase (GCK), hepatocyte nuclear factor-1 alpha (HNF1A, or TCF1), hepatocyte nuclear factor-4 alpha (HNF4A), insulin promoter factor-1 (IPF1 or PDX1), hepatocyte nuclear factor-1 beta (HNF1B or TCF2), and neurogenic differentiation 1 (NEUROD1). Mutations in the HNF1A gene are a common cause of MODY in the majority of populations studied. A total of 193 different mutations have been described in 373 families. The most common mutation is Pro291fs (P291fsinsC) in the polycytosine (poly C) tract of exon 4, which has been reported in 65 families. HNF4A mutations are rarer; 31 mutations reported in 40 families. Sensitivity to treatment with sulfonylurea tablets is a feature of both HNF1A and HNF4A mutations. The identification of an HNF1A or 4A gene mutation confirms a diagnosis of MODY and has important implications for clinical management.     

CDKN2A/2B基因多态性与妊娠糖尿病相关

目的研究CDKN2A/2B基因rs10811661的单核苷酸多态性(SNP),探讨其与妊娠糖尿病(GDM)的相关性。方法选取鲁西南地区正常糖耐量孕妇(NGT)100例、GDM患者120例、2型糖尿病(T2DM)患者100例作为研究对象,提取基因组DNA,采用PCR-RFLP方法检测CDKN2A/2B基因rs10811661多态性。结果 CDKN2A/2B基因rs10811661的TT、TC、CC 3种基因型分布在NGT组与GDM组间有显著差别(P<0.01),GDM组危险等位基因T分布频率显著高于NGT组(P<0.05)。3种基因型及等位基因分布在NGT组与T2DM组之间亦有显著差别(P<0.05)。结论在鲁西南地区女性人群中,CDKN2A/2B基因rs10811661 T/C多态性可能与妊娠糖尿病有明显相关性。     

中国人早发及多发糖尿病家系中HNF4A基因突变的筛查

目的探讨中国上海及周边地区早发及（或）多发糖尿病家系肝细胞核因子如基因（hepatocyte nuclear faetor-4α，HNF4A）的突变及变异发生情况。方法用PER-单链构象多态及序列分析的方法对154例早发及（或）多发糖尿病家系先证者进行HNF4A基因扫查。对发现的突变或变异采用PCR-限制性片段长度多态性方法在家系其他成员及93名正常对照者中进一步检测。结果在2例糖尿病家系先证者中发现2个同义突变，即N153N和A158A。其中N153N在1个早发性糖尿病家系中见到，且与糖尿病共分离。上述同义突变在正常者中未查到。此外，还发现3个变异位点：即IVS1＋308（A→G）（rs2071197），IVS1＋357（A→T）（rs2071198），IVS1-5（C→T）（rs745975）。3个位点基因型和等位基因频率在糖尿病先证者和正常对照者中无品著差别．结论HNF4A基因突变在中国人早发及（或）多发糖尿病家系中可能罕见。     

A polymorphism within the connective tissue growth factor (CTGF) gene has no effect on non-invasive markers of beta-cell area and risk of type 2 diabetes

Chromosomal locus 6q23 is strongly linked to type 2 diabetes (T2DM) and related features including insulin secretion in various ethnic populations. Connective tissue growth factor (CTGF) gene is an interesting T2DM candidate gene in this chromosome region. CTGF is a key mediator of progressive pancreatic fibrosis up-regulated in type 2 diabetes. In contrast, CTGF inactivation in mice compromises islet cell proliferation during embryogenesis. The aim of our study was to investigate an impact of CTGF genetic variation on pancreatic beta-cell function and T2DM pathogenesis. We studied the effect of a common CTGF polymorphism rs9493150 on the risk of the T2DM development in three independent German cohorts. Specifically, the association between CTGF polymorphism and non-invasive markers of beta-cell area derived from oral glucose tolerance test was studied in subjects without diabetes. Neither in the Metabolic Syndrome Berlin Potsdam (MESYBEPO) study (n=1026) (OR=0.637, CI (0.387-1.050); p=0.077) nor in the European Prospective Investigation into Cancer and Nutrition-Potsdam (EPIC-Potsdam) (n=3049) cohort (RR=0.77 CI (0.49-1.20), p=0.249 for the recessive homozygote in general model), a significant association with increased diabetes risk was observed. The risk allele of rs9493150 had also no effect on markers of beta-cell area in the combined analysis of the MESYBEPO and Tübingen Family Study (n=1826). In conclusion, the polymorphism rs9493150 in the 5'-untranslated region of the CTGF gene has no association with T2DM risk and surrogate markers of beta-cell area.     

Mutations in the Genes Encoding the Transcription Factors Hepatocyte Nuclear Factor 1 Alpha and 4 Alpha in Maturity‐Onset Diabetes of the Young and Hyperinsulinemic Hypoglycemia

Maturity‐onset diabetes of the young (MODY) is a monogenic disorder characterized by autosomal dominant inheritance of young‐onset (typically <25 years), noninsulin‐dependent diabetes due to defective insulin secretion. MODY is both clinically and genetically heterogeneous with mutations in at least 10 genes. Mutations in the HNF1A gene encoding hepatocyte nuclear factor‐1 alpha are the most common cause of MODY in most adult populations studied. The number of different pathogenic HNF1A mutations totals 414 in 1,247 families. Mutations in the HNF4A gene encoding hepatocyte nuclear factor‐4 alpha are a rarer cause of MODY with 103 different mutations reported in 173 families to date. Sensitivity to treatment with sulfonylurea tablets is a feature of both HNF1A and HNF4A mutations. The HNF4A MODY phenotype has been expanded by the reports of macrosomia in ～50% of babies, and more rarely, neonatal hyperinsulinemic hypoglycemia. The identification of an HNF1A or HNF4A gene mutation has important implications for clinical management in diabetes and pregnancy, but MODY is significantly underdiagnosed. Current research is focused on identifying biomarkers and developing probability models to identify those patients most likely to have MODY, until next generation sequencing technology enables cost‐effective gene analysis for all patients with young onset diabetes.     

Identification of eight novel glucokinase mutations in Italian children with maturity-onset diabetes of the young

Maturity-onset diabetes of the young (MODY) is a clinically heterogeneous group of disorders characterized by early onset non-insulin-dependent diabetes mellitus, autosomal dominant inheritance, and primary defect in the function of the beta cells of the pancreas. Mutations in the glucokinase (GCK) gene account for 8%-56% of MODY, with the highest prevalences being found in the southern Europe. While screening for GCK mutations in 28 MODY families of Italian origin, we identified 17 different mutations (corresponding to 61% prevalence), including eight previously undescribed ones. The novel sequence variants included five missense mutations (p.Lys161Asn c.483G>C in exon 4, p.Phe171Leu c.511T>C in exon 5 and p.Thr228Ala c.682A>G, p.Thr228Arg c.683C>G, p.Gly258Cys c.772G>T in exon 7), one nonsense mutation (p.Ser383Ter c.1148C>A in exon 9), the splice site variant c.1253+1G>T in intron 9, and the deletion of 12 nucleotides in exon 10 (p.Ser433_Ile436del c.1298_1309del12). Our study indicates that mutations in the GCK/MODY2 gene are a very common cause of MODY in the Italian population and broadens our knowledge of the naturally occurring GCK mutation repertoire.     

Genetic and clinical characteristics of maturity-onset diabetes of the young in Chinese patients

In Caucasians, maturity-onset diabetes of the young (MODY) is mostly caused by mutations in the hepatocyte nuclear factor (HNF)-1alpha (MODY3) and glucokinase (MODY2) genes. Most Japanese MODY patients, however, are not linked to known MODY genes. In this study, we examined the genetic and clinical characteristics of Chinese subjects with MODY. The study included 146 unrelated families fulfilling the minimum criteria for MODY: two consecutive generations of type II diabetes with at least one member diagnosed under the age of 25. We screened for mutations in the HNF-4alpha (MODY1), MODY2 and MODY3 genes by direct sequencing. Antibody to glutamic acid decarboxylase (GAD-Ab) was measured in subjects with MODY of unknown cause (MODYX). Insulin resistance index and other clinical data were compared in sex-, age- and duration-matched MODY3 and MODYX patients. In all, 13 families had MODY3 mutations and two had MODY2 mutations. No MODY1 mutation was found. Four of the 12 different MODY3 mutations were newly identified novel mutations (Q243E, A311D, P379R and P488fsdelC). In subjects with MODYX, 3% were GAD-Ab positive and 60% were overweight. Compared to MODY3 patients, MODYX patients had higher body mass index (P<0.02), higher insulin resistance index (P=0.001) and triglyceride level (P<0.02), lower HDL level (P=0.001) and more hypertension (P<0.05), but no significant difference in the prevalence of diabetic complications. In conclusion, MODY3 and MODY2 account for only 9 and 1%, respectively, of Chinese MODY. A majority of Chinese MODY patients are due to defects in unknown genes and appear to be characterized by insulin resistance.     

Evidence of association between single-nucleotide polymorphisms in lipid metabolism-related genes and type 2 diabetes mellitus in a Chinese population

Background: Type 2 diabetes mellitus (T2DM) is a complex chronic metabolic disorder triggered by insulin resistance in peripheral tissues. Evidence has shown that lipid metabolism and related genetic factors lead to insulin resistance. Hence, it is meaningful to investigate the association between single-nucleotide polymorphisms (SNPs) in lipid metabolism-related genes and T2DM.Methods: A total of 1,194 subjects with T2DM and 1,274 Non-diabetic subjects (NDM) were enrolled. Five SNPs in three genes (rs864745 in JAZF1, rs35767 in IGF1, and rs4376068, rs4402960, and rs6769511 in IGF2BP2) that contribute to insulin resistance involving lipid metabolism were genotyped using the MassArray method in a Chinese population.Results: The allele and genotypes of rs6769511 in IGF2BP2 were associated with T2DM (P=0.009 and P=0.002, respectively). In inheritance model analysis, compared with the T/T-C/T genotype, the C/C genotype of rs6769511 in IGF2BP2 was a risk factor for the development of T2DM (P<0.001, odds ratio [OR] =1.76; 95% confidence interval [CI]: 1.29-2.42). Haplotype analysis revealed associations of the rs4376068-rs4402960-rs6769511 haplotypes in IGF2BP2 with the development of T2DM (P=0.015). Additionally, rs4376068C-rs4402960T-rs6769511C was a risk haplotype for T2DM (OR=1.179; 95% CI: 1.033-1.346).Conclusion: The rs6769511 in IGF2BP2 was associated with T2DM susceptibility, and the rs4376068-rs4402960-rs6769511 haplotypes in IGF2BP2 was associated with the development of T2DM in a Chinese population.     

Calpain-10基因的SNP组合变异与2型糖尿病及其临床代谢性状的关系

目的 观察NIDDM1位点calpain-10基因（CAPN-10）的单核苷酸多态性（SNP）组合与中国人2型糖尿病（type2diabetes,T2DM)及有关临床代谢性状的关系。方法 268名上海地区中国人,其中144人为正常糖耐量（NGT）者,124例为T2DM患者,予口服75g葡萄糖后0、30、60、120及180分钟测血浆葡萄糖（PG）,胰岛素（INS）、C-肽（CP）及游离脂肪酸（FFA）,并估测胰岛β细胞岛素分泌及组织胰岛素敏感性,检测CAPN-10UCSNP44、-43、-19及-63基因型。结果 （1）中国人NGT者4个SNP的优势等位基因在UCSNP44为T（频率91%）、UCSNP43为G（89%）、UCSNP19为Ⅰ（3次32bp序列重复）（67%）及UCSNP63为C（79%）,这些频率与文献报道的其他种群频率间差异有显著性。（2）中国人NGT者中上述4个SNP基因型组合类型共见14种。群体中69%由4种基因型组合构成。按UCSNP44-43-19-63排列,这4种主要组合分别为组合A：TT-GG——DI-CC（单倍型组合1121/1111）（频率为10%）、组合B：TT-GA-Ⅱ-CC（1121/1221）（10%）、组合C：TT-GG-Ⅱ-CC（1121/1121）（26%）及组合D：TT——GG-DI-CT（1121/1112）（22%）。（3）CAPN-10上述单个SNP或4个SNP组合频率在NGT及T2DM者间差异均无显著性。（4）NGT者中主要基因型组合亚组间比较中可见临床代谢变量水平在组间呈从正常逐渐向糖耐量异常代谢情况移行的现象,组合A与组合D比较可见前者在糖兴奋后：（1）PG偏高且高峰后移;（2）FFA下降少且缓慢,后期无回升;（3）胰岛素偏高且高峰后移;（4）有胰岛素敏感性下降倾向,差异有显著性的比较者中半数以上经年龄、性别、体块指数及腰围校正后差异仍然存在。结论 CAPN-10变异与T2DM有关的临床代谢变量水平变异相关,此种相关有赖于CAPN-10基因各变异间形成的单倍型,且有赖于变异单倍型间的组合情况。     

Association between polymorphisms in SLC30A8, HHEX, CDKN2A/B, IGF2BP2, FTO, WFS1, CDKAL1, KCNQ1 and type 2 diabetes in the Korean population

According to recent genome-wide association studies, a number of single nucleotide polymorphisms (SNPs) are reported to be associated with type 2 diabetes mellitus (T2DM). The aim of the present study was to investigate the association among the polymorphisms of SLC30A8, HHEX, CDKN2A/B, IGF2BP2, FTO, WFS1, CDKAL1 and KCNQ1 and the risk of T2DM in the Korean population. This study was based on a multicenter case-control study, including 908 patients with T2DM and 502 non-diabetic controls. We genotyped rs13266634, rs1111875, rs10811661, rs4402960, rs8050136, rs734312, rs7754840 and rs2237892 and measured the body weight, body mass index and fasting plasma glucose in all patients and controls. The strongest association was found in a variant of CDKAL1 [rs7754840, odds ratio (OR) = 1.77, 95% CI = 1.50-2.10, p = 5.0 x 10(-11)]. The G allele of rs1111875 (OR = 1.43, 95% CI = 1.18-1.72, p = 1.8 x 10(-4)) in HHEX), the T allele of rs10811661 (OR = 1.47, 95% CI = 1.23-1.75, p = 2.1 x 10(-5)) in CDKN2A/B) and the C allele of rs2237892 (OR = 1.31, 95% CI = 1.10-1.56, p = 0.003) in KCNQ1 showed significant associations with T2DM. Rs13266634 (OR = 1.19, 95% CI = 1.00-1.42, p = 0.045) in SLC30A8 showed a nominal association with the risk of T2DM, whereas SNPs in IGF2BP2, FTO and WFS1 were not associated. In conclusion, we have shown that SNPs in HHEX, CDKN2A/B, CDKAL1, KCNQ1 and SLC30A8 confer a risk of T2DM in the Korean population.     

Possible association between CTLA4 DNA polymorphisms and early onset type 1 diabetes in a UK population

Linkage and association has been reported between CTLA4 DNA markers and susceptibility to type 1 diabetes in some populations, but not others. We performed case-control and family-based association studies to assess if the CTLA4 A49G and intron 1 C/T polymorphisms were associated with development of early onset type 1 diabetes in the Northern Ireland population. The distribution of A49G and C/T alleles in cases (n = 144) was similar to those observed in controls (n = 307). In contrast, significant distortions in allele transmissions from informative parents to probands were observed for both the A49G (P = 0.02) and C/T (P = 0.01) polymorphisms employing 297 nuclear families. Our results suggest that the CTLA4 gene may play a minor role in the overall genetic predisposition to type 1 diabetes in this UK population.     

Association study of polymorphisms in miRNAs with T2DM in Chinese population

Accumulated evidence indicates that microRNA (miRNA or miR) is involved in the development of type 2 diabetes (T2DM). Several studies have shown that single nucleotide polymorphisms (SNPs) located in miRNAs are associated with T2DM in Caucasian populations. The association studies of miRNA''s SNPs with T2DM in Asian are rarely reported, and there are distinct genetic differences between Caucasian and Asian populations. The focus of this study, therefore, is the association of T2DM with five SNPs (rs895819 in miR-27a, rs531564 in miR-124a, rs11888095 in miR-128a, rs3820455 in miR-194a and rs2910164 in miR-146a) located in five miRNAs in a Han Chinese population. A total of 738 subjects with T2DM and 610 non-diabetic subjects were genotyped using the TaqMan method. Next, the associations between the five SNPs with T2DM and individual metabolic traits were evaluated. Our data showed that the C allele of rs531564 in miR-124a may protect against T2DM (P=0.009, OR=0.758; 95%CI: 0.616-0.933). Conversely, the C allele of rs2910164 in miR-146a may increase the risk of developing T2DM (P<0.001, OR=1.459; 95%CI: 1.244-1.712). However, these five SNPs did not exhibit significant associations with individual metabolic traits in either the T2DM or non-diabetic groups. Our results revealed that genetic variations in miRNAs were associated with T2DM susceptibility in a Han Chinese population, and these results highlight the need to study the functional effects of these variants in miRNAs on the risk of developing T2DM.     

Genetic variants of OCT1 influence glycemic response to metformin in Han Chinese patients with type-2 diabetes mellitus in Shanghai

Aims/hypothesis: Genetic variation in OCT1 can influence the glycemic response to metformin. We evaluated the effects of the OCT1 single-nucleotide polymorphisms (SNPs), rs1867351, rs4709400, rs628031, and rs2297374, on metformin efficacy in type-2 diabetes mellitus (DM) patients. Methods: We performed a single-center prospective analysis of the distributions of these SNPs in a cohort of Han Chinese subjects in Shanghai, China (HCS), and evaluated the effects of each SNP on glycemic control in HCS DM patients following 3 months of incident metformin treatment. Results: The allele frequencies of rs4709400 and rs628031 in our HCS control group differed from those previously reported for Han Chinese subjects in Beijing (HCB), as well as those previously reported for Caucasians and Africans, whereas the allele frequencies of rs1867351 and rs2297374 were more similar to those in HCB subjects. The DM patients with the rs1867351 T/T or rs4709400 G/G genotype exhibited greater reductions in postprandial plasma glucose (PPG), compared to those with different genotypes of these SNPs. The DM patients with the rs2297374 C/T, rs4709400 G/G, or rs628031 G/G genotype exhibited greater reductions in fasting plasma glucose (FPG), and those with the rs1867351 T/T, rs628031 A/A, or rs2297374 C/T genotype exhibited greater reductions in HbA_1c , compared to those with different genotypes of these SNPs. Conclusions /interpretation: The rs1867351, rs4709400, rs628031, and rs2297374 SNPs of OCT1 have selective effects on FPG, PPG, and HbA_1c in HCS DM patients in response to metformin treatment. Future studies of these SNPs in larger samples of HCS DM patients are warranted.