Genetic and clinical characterisation of maturity-onset diabetes of the young in Spanish families

OBJECTIVE: To investigate the frequencies of the major maturity-onset diabetes of the young (MODY) subtypes in a panel of Spanish families and to assess phenotypic differences in patients with the different subtypes of MODY. METHODS: Forty-eight subjects from twenty families with clinical diagnosis of MODY were studied. They underwent a standardised clinical examination and a 75-g oral glucose tolerance test (OGTT) was performed. Estimations of insulin sensitivity (%S) and insulin secretion capacity (%B) were calculated by the computer-solved homeostasis model assessment (HOMA). Mutations in the coding regions of hepatocyte nuclear factor (HNF)-4alpha/MODY1, glucokinase (GCK/MODY2) and HNF-1alpha/MODY3 genes were investigated by single strand comformation polymorphism and sequencing analysis. RESULTS: Mutations in the GCK and HNF-1alpha genes were observed in 5 (25%) and 7 (35%) families respectively. Novel mutations included R385X, M238fsdelT, V226fsdelTinsAA and S418-7del11 in the GCK gene, and S121fsdelC, V133M, R159Q and V259D in the HNF-1alpha gene. No MODY1 families were found. Subjects which were neither MODY2 nor MODY3 (MODY-X) had a higher fasting glucose than subjects in the other groups. Insulin secretion capacity was similar in the three groups and the insulin sensitivity was decreased in MODY-X subjects. Glucose levels were significantly higher and insulin levels significantly lower, throughout the OGTT, in MODY3 compared with MODY2 subjects. CONCLUSIONS: Mutations in the GCK/MODY2 and HNF-1alpha/MODY3 genes account for the majority of cases in a panel of Spanish MODY families, with MODY3 being the most frequent subtype. The relative frequencies and the clinical characteristics of these MODY subtypes are in agreement with data previously reported in other European populations. MODY-X patients seem to present a heterogeneous clinical profile.     

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.     

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.     

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。     

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.     

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.     

Hepatocyte nuclear factor-1 alpha gene inactivation: cosegregation between liver adenomatosis and diabetes phenotypes in two maturity-onset diabetes of the young (MODY)3 families

Heterozygous germline mutations of the hepatocyte nuclear factor (HNF)-1 alpha are associated with maturity-onset diabetes of the young (MODY)3. Recently, the biallelic inactivation of the HNF-1 alpha gene was reported in liver adenomas. We show the occurrence of liver adenomatosis in six MODY3-affected patients from two unrelated and large families. Liver adenomatosis was characterized by the presence of numerous adenomas within a normal hepatic parenchyma. The HNF-1 alpha hot-spot germline mutation P291fs was identified in the two probands and in 16 relatives from the two families. The six patients affected by liver adenomatosis and diabetes exhibited the mutation. The analysis of liver-cell tumors from two affected patients evidenced the biallelic inactivation of HNF-1 alpha. The familial screening confirmed the clinical heterogeneity of the liver phenotype, from silent liver adenomatosis to fatal hemorrhage. These observations warrant the systematic screening for liver adenomatosis in MODY3 families to prevent its potentially deadly complications. Moreover, such screening may help to determine if a particular mutational spectrum of HNF-1 alpha is associated with liver adenomatosis and to establish its prevalence in this frequent form of diabetes in the young adult.     

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.     

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.     

Sensitivity to sulphonylureas in patients with hepatocyte nuclear factor-1alpha gene mutations: evidence for pharmacogenetics in diabetes.

INTRODUCTION: Maturity-onset diabetes of the young (MODY) is characterized by autosomal dominantly inherited, early-onset, non-insulin-dependent diabetes. Mutations in the hepatocyte nuclear factor (HNF)-1alpha gene are the commonest cause of MODY. Individual patients with HNF-1alpha mutations have been reported as being unusually sensitive to the hypoglycaemic effects of sulphonylurea therapy. We report three patients, attending a single clinic, with HNF-1alpha mutations that show marked hypersensitivity to sulphonylureas. CASE REPORTS: In cases 1 and 2 there were marked changes in HbA1c on cessation (4.4% and 5.8%, respectively) and reintroduction (5.0% and 2.6%) of sulphonylureas. Case 3 had severe hypoglycaemic symptoms on the introduction of sulphonylureas despite poor glycaemic control and was shown with a test dose of 2.5 mg glibenclamide to have symptomatic hypoglycaemia (blood glucose 2 mmol/l) after 4 h despite eating. CONCLUSIONS: HNF-1alpha MODY diabetic subjects are more sensitive to sulphonylureas than Type 2 diabetic subjects and this is seen in different families, with different mutations and may continue up to 13 years from diagnosis. This is an example of pharmacogenetics, with the underlying aetiological genetic defect altering the pharmacological response to treatment. The present cases suggest that in HNF-1alpha MODY patients: (i) sulphonylureas can dramatically improve glycaemic control and should be considered as initial treatment for patients with poor glycaemic control on an appropriate diet; (ii) hypoglycaemia may complicate the introduction of sulphonylureas and therefore very low doses of short acting sulphonylureas should be used initially; and (iii) cessation of sulphonylureas should be undertaken cautiously as there may be marked deterioration in glycaemic control.     

Islet autoimmunity and genetic mutations in Chinese subjects initially thought to have Type 1B diabetes.

AIMS: To explore the contribution of islet autoimmunity and genetic mutations in Chinese patients initially thought to have Type 1B diabetes. METHODS: A group of 33 Chinese patients with newly diagnosed Type 1B diabetes, were identified by the absence of autoantibodies to glutamic acid decarboxylase (GAD), IA-2, insulin, thyroid globulin or thyroid peroxidase, or high-risk HLA-DQ haplotypes. The cohort was further characterized by measurement of autoantibodies to carboxypeptidase H (CPH) and SOX13 using radioligand assays, and testing for genetic mutations associated with MODY3/MODY6 and mitochondrial diabetes. Mutations of HNF-1alpha (MODY3) and neuroD1/beta2 (MODY6) genes were screened using the single-strand conformation polymorphism (SSCP) technique and sequencing. Mitochondrial DNA mutations were analysed with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS: Within the cohort, we found one patient with a novel mutation, R321H (CGC-->CAC) in exon 5 of the HNF-1alpha gene, one with ND1 mt3316 G-->A mutation in mitochondrial DNA, five with Ala45Thr polymorphisms in the neuroD1/beta2 gene, and two patients with autoantibodies to SOX13. CONCLUSIONS: Some of the Chinese patients originally thought to have Type 1B diabetes do have other evidence of islet autoimmunity and genetic mutations involved in the underlying aetiology. This suggests that more rigorous screening for these conditions is needed before classifying subjects as having Type 1B diabetes.     

Mutations in the hepatocyte nuclear factor-1α gene in Caucasian families originally classified as having Type I diabetes

Summary Mutations in the hepatocyte nuclear factor-1α (HNF-1α) gene are the cause of maturity-onset diabetes of the young type 3 (MODY3), which is characterised by a severe impairment of insulin secretion and an early onset of the disease. Also at onset of diabetes some MODY patients show similar clinical symptoms and signs as patients with Type I (insulin-dependent) diabetes mellitus. The objective of this study was to estimate the prevalence of MODY3 patients misclassified as Type I diabetic patients. From a large population-based sample of unrelated Danish Caucasian Type I diabetic patients with an affected first degree relative, 39 patients (6.7 %) who did not carry any high-risk HLA-haplotypes, i. e. DR3 or DR4 or both were examined by single-strand conformational polymorphism scanning and direct sequencing of the coding region and the minimal promoter of the HNF-1α gene. Four of the 39 Type I diabetic patients (10 %) were identified as carrying mutations in the HNF-1α gene. One patient carried a missense mutation (Glu48Lys) in exon 1, two patients carried a missense mutation (Cys241Gly) in exon 4 and one patient carried a frameshift mutation (Pro291fsdelA) in exon 4. The mutations were all identified in heterozygous form, segregated with diabetes, and were not identified in 84 unrelated, healthy subjects. Furthermore, family history in three of the four families showed diabetes in four consecutive generations, suggestive of an autosomal dominant inheritance. In conclusion, about 10 % of Danish diabetic patients without a high-risk HLA-haplotype, originally classified as having Type I diabetes could have diabetes caused by mutations in the HNF-1α gene. Clinical awareness of family history of diabetes and mode of inheritance might help to identify and reclassify these diabetic subjects as MODY3 patients. [Diabetologia (1998) 41: 1528–1531] Received: 25 May 1998 and in revised form: 13 July 1998     

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