Genetic epidemiology of MODY in the Czech republic: new mutations in the MODY genes <Emphasis Type="Italic">HNF-4α</Emphasis>, <Emphasis Type="Italic">GCK</Emphasis> and <Emphasis Type="Italic">HNF-1α</Emphasis>

AIMS/HYPOTHESIS: The aim of this study was to examine the prevalence and nature of mutations in HNF4alpha/MODY1, GCK/MODY2 and HNF-1alpha/MODY3 genes in Czech subjects with clinical diagnosis of MODY. METHODS: We studied 61 unrelated index probands of Czech origin (28 males, 33 females) with a clinical diagnosis of MODY and 202 family members. The mean age of probands was 22.7+/-12.0 years (range, 6-62) and the mean age at the first recognition of hyperglycaemia was 14.7+/-6.0 years (range, 1-25). The promotor and coding regions inclusive intron exon boundaries of the HNF-4alpha, GCK and HNF-1alpha genes were examined by PCR-dHPLC (HNF-1alpha and GCK) and direct sequencing. RESULTS: We identified 20 different mutations in the HNF-4alpha, GCK and HNF-1alpha in 29 families (48% of all families studied), giving a relative prevalence of 5% of MODY1, 31% of MODY2 and 11.5% of MODY3 among the Czech kindred with MODY. Three of 3, 10 of 11 and 1 of 6 of the mutations identified in HNF-4alpha, GCK and HNF-1alpha respectively, were new. CONCLUSION/INTERPRETATION: Of the families 48% carried mutations in the MODY1-3 genes and of the identified mutations 70% were new. In 52% of Czech families with clinical characteristics of MODY, no mutations were found in the analysed genes. This finding shows that the majority of MODY mutations in a central European population are local and that other MODY genes could be responsible for autosomal dominant transmission of diabetes mellitus.     

Mutations in GCK and HNF-1alpha explain the majority of cases with clinical diagnosis of MODY in Spain

OBJECTIVE: The aim of this study was to group patients with MODY (maturity-onset diabetes of the young) according to the genetic alterations underlying the disease and to investigate their clinical characteristics. PATIENTS AND METHODS: Molecular analysis of GCK (MODY2), HNF-1alpha (MODY3), HNF-4alpha (MODY1) and HNF-1beta (MODY5) genes was performed by DNA sequencing in 95 unrelated index probands (47M/48F; mean age 9.9 +/- 5.2 years) with clinical diagnosis of MODY. After classification into MODY subtypes according to the genetic alterations, clinical characteristics were compared between the groups. RESULTS: Seventy-six families were shown to carry mutations in GCK (34 of them previously unreported), eight families presented HNF-1alpha mutations, and a large genomic rearrangement in HNF-1beta was found in a family. No alteration was found in HNF-4alpha. Thus, relative frequencies in the group studied were 80% MODY2, 8.5% MODY3 and 1% MODY5. Comparison of clinical parameters according to genetic status showed significant differences between MODY2 and MODY3 patients in age at diagnosis (9.4 +/- 5.4 years vs. 12.7 +/- 4.6 years), diagnosis (impaired glucose tolerance vs. diabetes), diagnostic test used (OGTT vs. fasting glucose), treatment (diet and exercise vs. insulin/oral antidiabetic agents) and birth weight (2.96 +/- 0.44 kg vs. 3.40 +/- 0.67 kg). CONCLUSION: Almost 90% of the MODY cases in the group studied are explained by mutations in the major genes GCK (MODY2) and HNF-1alpha(MODY3), although differences in the relative prevalence of each form could be partly due to patient referral bias (paediatric vs. adult). In general, patients with MODY2 were diagnosed at an earlier age in life than MODY3 patients and had a milder form of diabetes. Moreover, the majority of patients with MODY2 mutations were treated with diet whereas half of MODY3 patients received pharmacological treatment.     

Nine novel mutations in maturity-onset diabetes of the young (MODY) candidate genes in 22 Spanish families

The aims of this study were to estimate the prevalence of major maturity-onset diabetes of the young (MODY) subtypes in Spanish MODY families and to analyze genotype-phenotype correlations. Twenty-two unrelated pediatric MODY patients and 97 relatives were screened for mutations in the coding region of the glucokinase (GCK), hepatic nuclear factor- HNF-1alpha and HNF4alpha genes using PCR-single strand conformation polymorphism and/or direct sequencing. In families carrying GCK mutations, the influence of genetic defects on fetal growth was investigated by comparing the birth weights of 32 offspring discordant for the mutations. Mutations in MODY genes were identified in 64% of the families. GCK/MODY2 mutations were the most frequently found, in 41%: seven novel (R369P, S411F, M298K, C252Y, Y108C, A188E, and S383L) and 2 already described mutations. Four pedigrees (18%) harbored mutations in the HNF-1alpha/MODY3 gene, including a previously unreported change (R271G). One family (4%) carried a novel mutation in the HNF-4alpha gene (IVS5-2delA), representing the first report of a MODY1 pedigree in the Spanish population. The age at diagnosis was prepubertal in MODY2 index patients and pubertal in MODY3 patients. Overt diabetes was rare in MODY2 and was invariably present in MODY3 index patients. Chronic complications of diabetes were absent in the MODY2 population and were present in more than 40% of all relatives of MODY3. Birth weight was lower in the presence of a GCK fetal mutation when the mutation was of paternal origin. The MODY1 patient was diagnosed at 15 yr of age. She developed intermittent microalbuminuria despite good metabolic control, and severe late-onset complications were common within her family. Mutations in the GCK/MODY2 gene are the most common cause of MODY in our population as recruited from pediatric and adolescent index patients. The inheritance of GCK defects by the fetus results in a reduction of birth weight. Clinical expression of MODY3 and MODY1 mutations, the second and third groups of defects found, was more severe, including the frequent development of chronic complications.     

Triple genetic variation in the HNF-4alpha gene is associated with early-onset type 2 diabetes mellitus in a philippino family

Maturity-onset diabetes of the young-type 1 (MODY1) is a form of monogenic type 2 diabetes mellitus (T2DM) with long-term complications due to mutations in the HNF-4alpha gene. The HNF-4alpha gene is involved in hepatic differentiation and expression of genes regulating glucose transport, glycolysis, and lipid metabolism. The abnormal glucose-stimulated insulin secretion in MODY1 subjects may be due to reduced glucose transport and glycolysis. To date, 14 mutations in the HNF-4alpha gene have been identified as a cause of either MODY1 or late-onset type 2 diabetes. So far, no screening has been performed in subjects from the Philippines. We recruited a Philippino family with autosomal dominant early-onset type 2 diabetes and screened the proband for mutations in the genes for HNF-1alpha, GCK, HNF-4alpha, IPF-1, HNF-6, and NGN3. We identified a new missense mutation in exon 5 (V199I) of the HNF-4alpha gene and 2 new single-nucleotide substitutions in intron 4, IVS4-nt4 (G --> A) and IVS4-nt20 (C --> T), all cosegregating with diabetes in the 3 affected available siblings. These variations were not present in 100 normal healthy subjects. Bioinformatic analysis suggests that these variations in the whole, and overall the IVS4-nt4 variation located at splicing site, may affect the splicing potential of intron 4. We have biochemically and clinically characterized the Philippine-1 family. We suggest that the V199I missense mutation located in the ligand binding/dimerization domain of HNF-4alpha contributes to type 2 diabetes in the Philippine-1 family. The intron variations may contribute susceptibility to diabetes.     

Mutations of maturity-onset diabetes of the young (MODY) genes in Thais with early-onset type 2 diabetes mellitus

Objective  Six known genes responsible for maturity-onset diabetes of the young (MODY) were analysed to evaluate the prevalence of their mutations in Thai patients with MODY and early-onset type 2 diabetes.
Patients and methods  Fifty-one unrelated probands with early-onset type 2 diabetes, 21 of them fitted into classic MODY criteria, were analysed for nucleotide variations in promoters, exons, and exon–intron boundaries of six known MODY genes, including HNF-4α , GCK , HNF-1α , IPF-1 , HNF-1β , and NeuroD1/β2 , by the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) method followed by direct DNA sequencing. Missense mutations or mutations located in regulatory region, which were absent in 130 chromosomes of non-diabetic controls, were classified as potentially pathogenic mutations.
Results  We found that mutations of the six known MODY genes account for a small proportion of classic MODY (19%) and early-onset type 2 diabetes (10%) in Thais. Five of these mutations are novel including GCK R327H, HNF-1α P475L, HNF-1α G554fsX556, NeuroD1 –1972 G > A and NeuroD1 A322N. Mutations of IPF-1 and HNF-1β were not identified in the studied probands.
Conclusions  Mutations of the six known MODY genes may not be a major cause of MODY and early-onset type 2 diabetes in Thais. Therefore, unidentified genes await discovery in a majority of Thai patients with MODY and early-onset type 2 diabetes.     

青少年的成人起病型糖尿病2型和3型混合家系一例临床分析并文献复习

目的探究葡萄糖激酶基因(GCK)及肝细胞核因子1α基因(HNF-1α)同时突变致青少年的成人起病型糖尿病(MODY)的临床和遗传学特点。方法对北京协和医院2017年9月诊断的一例MODY患者及其家系的临床特征、实验室资料进行分析;对家系成员进行MODY相关致病基因检测。结果该家系的5名成员检测到GCK基因(NM_000162)c.686C>T(p.Thr229Met)杂合突变。其中3名成员同时检测到HNF-1α基因(NM_001306179)c.1531C>G(p.Gln511Glu)杂合突变。结论MODY混合家系GCK及HNF-1α基因突变导致同一家系出现不同的MODY类型。诊断时需考虑混合家系的可能性,以准确诊断。     

A novel nonsense mutation in GCK exon 9 co-segregates with diabetes phenotype.

Maturity-onset diabetes of the young is an autosomal dominant form of non-insulin dependent diabetes mellitus and is caused by mutations in at least six different genes. In the most common forms, i.e. MODY2 and MODY3, the glucokinase (GCK) and the hepatocyte nuclear factor (HNF)-1alpha gene is affected, respectively. We have screened the GCK gene and HNF-1alpha gene by direct sequencing in three German families with early onset type-2-diabetes, possibly MODY. Next to known polymorphisms we have identified two novel intronic insertions in GCK and a novel non-sense mutation in exon 9 (C364 X). The latter mutation has an autosomal dominant inheritance pattern. Accordingly, this novel mutation segregates with diabetes phenotype in this family.     

Mutation screening in 18 Caucasian families suggest the existence of other MODY genes

Summary Maturity-onset diabetes of the young (MODY) is a heterogeneous subtype of non-insulin-dependent diabetes mellitus characterised by early onset, autosomal dominant inheritance and a primary defect in insulin secretion. To date five MODY genes have been identified: hepatocyte nuclear factor-4 alpha (HNF-4 α/MODY1/TCF14) on chromosome 20 q, glucokinase (GCK/MODY2) on chromosome 7 p, hepatocyte nuclear factor-1 alpha (HNF-1 α/MODY3/TCF1) on chromosome 12 q, insulin promoter factor-1 (IPF1/MODY4) on chromosome 13 q and hepatocyte nuclear factor-1 beta (HNF-1 β/MODY5/TCF2) on chromosome 17cen-q. We have screened the HNF-4 α, HNF-1 α and HNF-1 β genes in members of 18 MODY kindreds who tested negative for glucokinase mutations. Five missense (G31D, R159W, A161T, R200W, R271W), one substitution at the splice donor site of intron 5 (IVS5nt + 2T→A) and one deletion mutation (P379fsdelT) were found in the HNF-1 α gene, but no MODY-associated mutations were found in the HNF-4 α and HNF-1 β genes. Of 67 French MODY families that we have now studied, 42 (63 %) have mutations in the glucokinase gene, 14 (21 %) have mutations in the HNF-1 α gene, and 11 (16 %) have no mutations in the HNF-4 α, IPF1 and HNF-1 β genes. Eleven families do not have mutations in the five known MODY genes suggesting that there is at least one additionnal locus that can cause MODY. [Diabetologia (1998) 41: 1017–1023] Received: 5 January 1998 and in revised form: 8 April 1998     

Low prevalence of MODY2 and MODY3 mutations in Brazilian individuals with clinical MODY phenotype

Prevalence of MODY2 and MODY3 mutations has been assessed in 23 Brazilian families with MODY phenotype. Mutations in HNF-1alpha have been found in 3 families (13%) and 2 families (8.7%) had new glucokinase mutations. These genes do not explain the majority of MODY cases in Brazilian population.     

Regulation of human insulin, IGF-I, and multidrug resistance protein 2 promoter activity by hepatocyte nuclear factor (HNF)-1beta and HNF-1alpha and the abnormality of HNF-1beta mutants

Mutations in hepatocyte nuclear factor-1beta (HNF-1beta) lead to type 5 maturity-onset diabetes of the young (MODY5). Moreover, mutations in the HNF-1beta gene might cause multiorgan abnormalities including renal diseases, genital malformations, and abnormal liver function. The objective of this study was to investigate the molecular mechanism of diabetes mellitus, intrauterine growth retardation, and cholestasis observed in MODY5 patients. We analyzed the transactivity of wild-type and three mutant HNF-1beta on native human insulin, IGF-I, and multidrug resistance protein 2 (MRP2) promoters in combination with HNF-1alpha, using a reporter-assay system in transiently transfected mammalian cells. In the human insulin gene promoter, we found that the cooperation of HNF-1alpha and HNF-1beta is prominent. Absence of this cooperation was observed in all of the HNF-1beta mutants. In the human IGF-I and MRP2 promoters, we found that the HNF-1beta His153Asn (H153N) mutant had a mutant-specific repressive effect on both HNF-1alpha and wild-type HNF-1beta transactivity. Absence of the cooperation of HNF-1beta mutants with HNF-1alpha in the human insulin gene promoter might be one cause of defective insulin secretion. The H153N mutant-specific repression of HNF-1alpha and HNF-1beta transactivity in human IGF-I and MRP2 promoters might explain the case-specific clinical features of growth retardation and cholestasis observed only in early infancy. We found differential property of HNF-1alpha/HNF-1beta activity and the effect of HNF-1beta mutants by the promoters. We consider that analyses of HNF-1beta mutants on the intended human native promoters in combination with HNF-1alpha may be useful in investigating the molecular mechanisms of the various features in MODY5.     

Glucokinase mutations in young children with hyperglycemia

BACKGROUND: The etiology of mild hyperglycemia without ketoacidosis in young children is often unknown. Maturity onset diabetes of youth (MODY) is a form of diabetes mellitus (DM) characterized by fasting hyperglycemia without evidence for autoimmune destruction of beta-cells. METHODS: We genetically analyzed four families of young children with fasting hyperglycemia with family histories of diabetes for mutations in the genes for hepatocyte nuclear factor 4 alpha (HNF4alpha), glucokinase (GCK), and hepatocyte nuclear factor 1 alpha (HNF1alpha), the genes responsible for MODY1, MODY2, and MODY3, respectively. RESULTS: We identified mutations in GCK (Gly258Asp, Arg303Trp, and Arg191Gln) in three of the four families. Molecular genetic characterization in these children clarified the etiology and prognosis of the hyperglycemia and allowed discontinuation of insulin therapy in one family. CONCLUSIONS: We conclude that molecular evaluation for MODY in children with mild fasting hyperglycemia without ketosis with family histories of diabetes can provide important prognostic information to guide therapy and exclude preclinical type 1 diabetes mellitus.     

Mutations in the hepatocyte nuclear factor-1alpha gene in Chinese MODY families: prevalence and functional analysis

AIMS/HYPOTHESIS: Maturity-onset diabetes of the young is an autosomal dominant form of diabetes characterised by an early age of onset (usually <25 years). We investigated the prevalence and trans-activating activity of hepatocyte nuclear factor (HNF) -1 alpha mutations in southern Chinese families with MODY. METHODS: We screened for mutations in the HNF-1 alpha gene in 50 unrelated southern Chinese families, which fulfilled the minimum criteria for MODY. Functional properties of the mutant proteins were investigated using site-directed mutagenesis and luciferase reporter assay. RESULTS: Five of the 50 (10%) families were found to have mutations in the coding region, including a new nonsense mutation Q176X and four reported mutations (frameshift mutation P379fsdelCT, nonsense mutation R171X, missense mutations G20R and P112L). These mutations had decreased trans-activating activity on the human insulin gene promoter. We also detected a new intronic sequence variation IVS7nt-6 G-->A, which co-segregated with diabetes. The intronic variation creates a potential splice acceptor site and might alter the splicing of the HNF-1 alpha mRNA. CONCLUSION/INTERPRETATION: Mutations in the HNF-1 alpha gene seem to be an important cause of MODY in southern Chinese. The mutations could affect normal islet function by altering the expression of target genes.     

Insights into pathogenesis of five novel GCK mutations identified in Chinese MODY patients

ObjectiveHeterozygous inactivating mutations in GCK are associated with defects in pancreatic insulin secretion and/or hepatic glycogen synthesis leading to mild chronic hyperglycaemia of maturity onset diabetes of young type 2 (MODY2). However, the effect of naturally occurring GCK mutations on the pathogenesis for MODY2 hyperglycaemia remains largely unclear, especially in the Asian population. The aim of this study is to explore the potential pathogenicity of novel GCK mutations related to MODY2.MethodsGenetic screening for GCK mutations from 96 classical MODY families was performed, and structure-function characterization and clinical profile of identified GCK mutations were conducted.ResultsFive novel (F195S, I211T, V222D, E236G and K458R) and five known (T49N, I159V, R186X, A188T and M381T) mutations were identified and co-segregated with hyperglycaemia in their pedigrees. R186X generates non-functional truncated form and V222D and E236G fully inactivate glucokinase due to severe structure disruptions. The other seven GCK mutations exhibited marked reductions in catalytic efficiency and thermo-stability; notably, the interaction with GKRP was significantly enhanced in I211T, I159V, T49N and K458R, reduced in F195S and M381T, and completely lost with A188T. 31% (17/55) of MODY2 patients showed signs of insulin resistance. Conventional hypoglycaemia treatment did not improve the HbA1C in MODY2 patients when insulin resistance is not present.ConclusionsFive novel GCK mutations have been identified in Chinese MODY. The defects in enzymatic activity and protein stability, together with alteration of GKRP binding on GCK mutants may synergistically contribute to the development of MODY2 hyperglycaemia. No treatment should be prescribed to MODY2 patients when insulin resistance is not present.     

Identification and functional characterization of a novel mutation of hepatocyte nuclear factor-1α gene in a Korean family with MODY3

AIMS/HYPOTHESIS: After screening 16 Korean families with early onset Type 2 diabetes in search for hepatocyte nuclear factor (HNF) -1alpha gene mutation, we identified a novel missense mutation (R263L) associated with MODY phenotype. We studied the biological characteristics of the mutation and the potential functional consequences based on the crystallographic structure of HNF-1alpha in complex with DNA. METHODS: DNA from subjects with a familial form of early onset diabetes was isolated and HNF-1alpha was sequenced. The R263L substitution was generated by PCR-based sited-directed mutagenesis. Functional and biochemical studies were conducted by reporter assay using glucose-transporter type 2 (GLUT2) or insulin promoters and electrophoretic mobility shift assay, respectively. RESULTS: Transfection of wild-type HNF-1alpha increased the reporter activities of GLUT2 and insulin promoters in NIH3T3 and SK-Hep1 cells, while R263L mutant was defective in transactivation of those promoters. Both wild-type HNF-1alpha and R263L mutant could not transactivate GLUT2 and insulin promoters in MIN6N8 insulinoma cells. R263L mutant had a defective cooperation with its heterodimeric partner HNF-1beta or coactivator p300. R263L mutant protein displayed greatly reduced DNA binding ability, despite its comparable protein stability to the wild-type HNF-1alpha. CONCLUSION/INTERPRETATION: These results suggest that the mutation of HNF-1alpha at codon 263 from arginine to leucine leads to the development of MODY3 through decreased insulin production and defective glucose sensing. These findings are in good agreement with the crystal structure in which R263 makes hydrogen bonds with phosphorus atoms of DNA backbone to mediate the stable binding of HNF-1alpha homeodomain to the promoter.