Characteristics of maturity onset diabetes of the young in a large diabetes center

Maturity-onset diabetes of the young (MODY) - in search of ideal diagnostic criteria and precise treatment

Maturity-onset diabetes of the young (MODY) is a spectrum of clinically heterogenous forms of monogenic diabetes mellitus characterized by autosomal dominant inheritance, onset at a young age, and absence of pancreatic islets autoimmunity. This rare form of hyperglycemia, with clinical features overlapping with type 1 and type 2 diabetes mellitus, has 14 subtypes with differences in prevalence and complications occurrence which tailor therapeutic approach. MODY phenotypes differ based on the gene involved, gene penetrance and expressivity. While MODY 2 rarely leads to diabetic complications and is easily managed with lifestyle interventions alone, more severe subtypes, such as MODY 1, 3, and 6, require an individualized treatment approach to maintain a patient's quality of life and prevention of complications. This review summarizes current evidence on the presentation, diagnosis, and management of MODY, an example of a genetic cause of hyperglycemia that calls for a precision medicine approach.

High Frequency of Recessive WFS1 Mutations Among Indian Children With Islet Antibody-negative Type 1 Diabetes

BACKGROUND

While the frequency of islet antibody-negative (idiopathic) type 1 diabetes mellitus (T1DM) is reported to be increased in Indian children, its aetiology has not been studied. We investigated the role of monogenic diabetes in the causation of islet antibody-negative T1DM.

METHODS

We conducted a multicenter, prospective, observational study of 169 Indian children (age 1-18 years) with recent-onset T1DM. All were tested for antibodies against GAD65, islet antigen-2, and zinc transporter 8 using validated ELISA. Thirty-four islet antibody-negative children underwent targeted next-generation sequencing for 31 genes implicated in monogenic diabetes using the Illumina platform. All mutations were confirmed by Sanger sequencing.

RESULTS

Thirty-five (21%) children were negative for all islet antibodies. Twelve patients (7% of entire cohort, 34% of patients with islet antibody-negative T1DM) were detected to have pathogenic or likely pathogenic genetic variants. The most frequently affected locus was WFS1, with 9 patients (5% of entire cohort, 26% of islet antibody-negative). These included 7 children with homozygous and 1 patient each with a compound heterozygous and heterozygous mutation. Children with Wolfram syndrome 1 (WS) presented with severe insulin-requiring diabetes (including 3 patients with ketoacidosis), but other syndromic manifestations were not detected. In 3 patients, heterozygous mutations in HNF4A, ABCC8, and PTF1A loci were detected.

CONCLUSION

Nearly one-quarter of Indian children with islet antibody-negative T1DM had recessive mutations in the WFS1 gene. These patients did not exhibit other features of WS at the time of diagnosis. Testing for monogenic diabetes, especially WS, should be considered in Indian children with antibody-negative T1DM.

Investigation of Monogenic Diabetes Genes in Thai Children with Autoantibody Negative Diabetes Requiring Insulin

Purpose

The objective of this study was to clarify the phenotypic characteristics of monogenic diabetes abnormalities in Thai children with autoantibody-negative insulin.

Patients and Methods

Two hundred and thirty-one Thai type 1 diabetes (T1D) patients out of 300 participants with recent-onset diabetes were analyzed for GAD65 and IA2 pancreatic autoantibodies. A total of 30 individuals with T1D patients with negative autoantibody were screened for 32 monogenic diabetes genes by whole-exome sequencing (WES).

Results

All participants were ten men and twenty women. The median age to onset of diabetes was 8 years and 3 months. A total of 20 people with monogenic diabetes carried genes related to monogenic diabetes. The PAX4 (rs2233580) in ten patients with monogenic diabetes was found. Seven variants of WFS1 (Val412Ala, Glu737Lys, Gly576Ser, Cys673Tyr, Arg456His, Lys424Glu, and Gly736fs) were investigated in patients in this study. Furthermore, the pathogenic variant, rs115099192 (Pro407Gln) in the GATA4 gene was found. Most patients who carried PAX4 (c.575G>A, rs2233580) did not have a history of DKA. The pathogenic variant GATA4 variant (c.1220C>A, rs115099192) was found in a patient with a history of DKA.

Conclusion

This study demonstrated significant genetic overlap between autoantibody-negative diabetes and monogenic diabetes using WES. All candidate variants were considered disease risk with clinically significant variants. WES screening was the first implemented to diagnose monogenic diabetes in Thai children, and fourteen novel variants were identified in this study and need to be investigated in the future.

American Association of Clinical Endocrinology Clinical Practice Guideline: Developing a Diabetes Mellitus Comprehensive Care Plan-2022 Update

OBJECTIVE

The objective of this clinical practice guideline is to provide updated and new evidence-based recommendations for the comprehensive care of persons with diabetes mellitus to clinicians, diabetes-care teams, other health care professionals and stakeholders, and individuals with diabetes and their caregivers.

METHODS

The American Association of Clinical Endocrinology selected a task force of medical experts and staff who updated and assessed clinical questions and recommendations from the prior 2015 version of this guideline and conducted literature searches for relevant scientific papers published from January 1, 2015, through May 15, 2022. Selected studies from results of literature searches composed the evidence base to update 2015 recommendations as well as to develop new recommendations based on review of clinical evidence, current practice, expertise, and consensus, according to established American Association of Clinical Endocrinology protocol for guideline development.

RESULTS

This guideline includes 170 updated and new evidence-based clinical practice recommendations for the comprehensive care of persons with diabetes. Recommendations are divided into four sections: (1) screening, diagnosis, glycemic targets, and glycemic monitoring; (2) comorbidities and complications, including obesity and management with lifestyle, nutrition, and bariatric surgery, hypertension, dyslipidemia, retinopathy, neuropathy, diabetic kidney disease, and cardiovascular disease; (3) management of prediabetes, type 2 diabetes with antihyperglycemic pharmacotherapy and glycemic targets, type 1 diabetes with insulin therapy, hypoglycemia, hospitalized persons, and women with diabetes in pregnancy; (4) education and new topics regarding diabetes and infertility, nutritional supplements, secondary diabetes, social determinants of health, and virtual care, as well as updated recommendations on cancer risk, nonpharmacologic components of pediatric care plans, depression, education and team approach, occupational risk, role of sleep medicine, and vaccinations in persons with diabetes.

CONCLUSIONS

This updated clinical practice guideline provides evidence-based recommendations to assist with person-centered, team-based clinical decision-making to improve the care of persons with diabetes mellitus.

Monogenic diabetes in adults: A multi-ancestry study reveals strong disparities in diagnosis rates and clinical presentation

AIM

Identification of monogenic diabetes (MgD) conveys benefits for patients' care. Algorithms for selecting the patients to be genetically tested have been established in EuroCaucasians, but not in non-EuroCaucasian individuals. We assessed the diagnosis rate, the phenotype of MgD, and the relevance of selection criteria, according to ancestry in patients referred for a suspected MgD.

METHODS

Seven genes (GCK, HNF1A, HNF4A, HNF1B, ABCC8, KCNJ11, INS) were analyzed in 1975 adult probands (42% non-EuroCaucasians), selected on the absence of diabetes autoantibodies and ≥2 of the following criteria: age ≤40 years and body mass index <30 kg/m² at diagnosis, and a family history of diabetes in ≥2 generations.

RESULTS

Pathogenic/likely pathogenic variants were identified in 6.2% of non-EuroCaucasian and 23.6% of EuroCaucasian patients (OR 0.21, [0.16-0.29]). Diagnosis rate was low in all non-EuroCaucasian subgroups (4.1-11.8%). Common causes of MgD (GCK, HNF1A, HNF4A), but not rare causes, were less frequent in non-EuroCaucasians than in EuroCaucasians (4.1%, vs. 21.1%, OR 0.16 [0.11-0.23]). Using ethnicity-specific body mass index cutoffs increased the diagnosis rate in several non-EuroCaucasian subgroups.

CONCLUSION

The diagnosis rate of MgD is low in non-EuroCaucasian patients, but may be improved by tailoring selection criteria according to patients'ancestry.

Clinical and genetic characterization and long-term evaluation of individuals with maturity-onset diabetes of the young (MODY): The journey towards appropriate treatment

AIMS

To describe the clinical and genetic characteristics and long-term follow-up of a cohort with maturity-onset diabetes of the young (MODY), and to evaluate how molecular diagnosis impacted on treatment.

METHODS

A large observational, retrospective, cohort study included individuals referred to the University of São Paulo's Monogenic Diabetes Unit between 2011 and 2020. Comprehensive clinical and genetic evaluations were performed.

RESULTS

Overall, 228 individuals (190 GCK-MODY and 38 HNF1A-MODY) were enrolled. Sixty-two different GCK gene mutations (5 novel) and 17 HNF1A gene mutations (2 novel) were found. Data were available on treatment status for 76 index individuals with GCK-MODY. Before molecular diagnosis, nutritional intervention alone was used in 41 cases (53.9%). After molecular diagnosis, this number increased to 72 (94.8%). Glycated haemoglobin (HbA_1c) remained stable over the 6-year follow-up period: 6.5% (47 mmol/mol) at the first and 6.3% (45 mmol/mol) at the final visit (p = 0.056). Prior to molecular diagnosis, 7/21 (33.3%) HNF1A-MODY individuals were using sulfonylurea compared to 17/21 (81%) after testing. After a median of 5 years on sulfonylureas, HbA_1c values improved from 7.5% (58 mmol/mol) to 6.5% (48 mmol/mol) (p = 0.006).

CONCLUSIONS

Molecular diagnosis resulted in appropriate adjustment of treatment in approximately 80% of participants with GCK-MODY or HNF1A-MODY.

When do we need to suspect maturity onset diabetes of the young in patients with type 2 diabetes mellitus?

OBJECTIVE

Maturity onset diabetes of the young (MODY) patients have clinical heterogeneity as shown by many studies. Thus, often it is misdiagnosed to type 1 or type 2 diabetes(T2DM). The aim of this study is to evaluate MODY mutations in adult T2DM patients suspicious in terms of MODY, and to show clinical and laboratory differences between these two situations.

METHODS

In this study, we analyzed 72 type 2 diabetic patients and their relatives (35F/37M) who had been suspected for MODY and referred to genetic department for mutation analysis. The gene mutations for MODY have been assessed in the laboratory of Marmara University genetics. Totally 67 (32F/35M; median age 36.1) diabetic patients were analyzed for 7 MODY mutations. Twelve patients who have uncertain mutation (VUS) were excluded from study for further evaluation. MODY(+) (n:30) patients and T2DM patients (n:25) were compared for clinical and laboratory parameters.

RESULTS

In MODY(+) subjects, mutations in GCK (MODY 2) (n:12; 40%) were the most common followed by HNF4A (MODY 1) (n:4; 13.3%). Diabetes diagnosis age was younger in MODY(+) group but not statistically significant. Sixty-six percent of MODY(+) subjects had diabetes history at 3-consecutive generations in their family compared with 28% of T2DM patients statistically significant (p:0.006). Gender, BMI, C-peptide, HbA1c, lipid parameters, creatinine, GFR, microalbuminuria, vitamin D and calcium were not statistically different between the groups.

CONCLUSION

According to present study results, MODY mutation positivity is most probable in young autoantibody (-) diabetic patients diagnosed before 30 years of age, who have first degree family history of diabetes.

Next- generation sequencing is an effective method for diagnosing patients with different forms of monogenic diabetes

AIM

Monogenic diabetes (MD) represents 5-7% of antibody-negative diabetes cases and is a heterogeneous group of disorders.

METHODS

We used targeted next-generation sequencing (NGS) on Illumina NextSeq 550 platform involving the SureSelect assay to perform genetic and clinical characteristics of a study group of 684 individuals, including 542 patients referred from 12 Polish Diabetes Centers with suspected MD diagnosed between December 2016 and December 2019 and their 142 family members (FM).

RESULTS

In 198 probands (36.5%) and 66 FM (46.5%) heterozygous causative variants were confirmed in 11 different MD-related genes, including 31 novel mutations, with the highest number in the GCK gene (206/264), 22/264 in the HNF1A gene and 8/264 in the KCNJ11 gene. Of the 183 probands with MODY1-5 diabetes, 48.6% of them were diagnosed at the pre-diabetes stage and most of them (68.7%) were on diet only at the time of genetic diagnosis, while 31.3% were additionally treated with oral hypoglycaemic drugs and/or insulin.

CONCLUSIONS

In summary, the results obtained confirm the efficacy of targeted NGS method in the molecular diagnosis of patients with suspected MD and broaden the spectrum of new causal variants, while updating our knowledge of the clinical features of patients defined as having MD.

Diabetes Mellitus Diagnosed in Childhood and Adolescence With Negative Autoimmunity: Results of Genetic Investigation

Monogenic diabetes is a rare form of diabetes, accounting for approximately 1% to 6% of pediatric diabetes patients. Some types of monogenic diabetes can be misdiagnosed as type 1 diabetes in children or adolescents because of similar clinical features. Identification of the correct etiology of diabetes is crucial for clinical, therapeutic, and prognostic issues. Our main objective was to determine the prevalence of monogenic diabetes in patients with diabetes mellitus, diagnosed in childhood or in adolescence, and negative autoimmunity. We retrospectively analyzed clinical data of 275 patients diagnosed with insulin-dependent diabetes at age <18yr in the last 10 years. 8.4% of subjects has negative autoimmunity. Their DNA was sequenced by NGS custom panel composed by 45 candidate genes involved in glucose metabolism disorder. Two novel heterozygous pathogenic or likely pathogenic variants (10,5% of autoantibody negative subjects) were detected: the frameshift variant c.617_618insA in NEUROD1 exon 2 and the missense change c.116T>C in INS exon 2. Our study corroborates previous results of other reports in literature. NGS assays are useful methods for a correct diagnosis of monogenic diabetes, even of rarest forms, highlighting mechanisms of pediatric diabetes pathogenesis.

Exome sequencing in children with clinically suspected maturity-onset diabetes of the young

OBJECTIVE

Commercial gene panels identify pathogenic variants in as low as 27% of patients suspected to have MODY, suggesting the role of yet unidentified pathogenic variants. We sought to identify novel gene variants associated with MODY.

RESEARCH DESIGN AND METHODS

We recruited 10 children with a clinical suspicion of MODY but non-diagnostic commercial MODY gene panels. We performed exome sequencing (ES) in them and their parents.

RESULTS

Mean age at diabetes diagnosis was 10 (± 3.8) years. Six were females; 4 were non-Hispanic white, 5 Hispanic, and 1 Asian. Our variant prioritization analysis identified a pathogenic, de novo variant in INS (c.94G > A, p.Gly32Ser), confirmed by Sanger sequencing, in a proband who was previously diagnosed with "autoantibody-negative type 1 diabetes (T1D)" at 3 y/o. This rare variant, absent in the general population (gnomAD database), has been reported previously in neonatal diabetes. We also identified a frameshift deletion (c.2650delC, p.Gln884AsnfsTer57) in RFX6 in a child with a previous diagnosis of "autoantibody-negative T1D" at 12 y/o. The variant was inherited from the mother, who was diagnosed with "thin type 2 diabetes" at 25 y/o. Heterozygous protein-truncating variants in RFX6 gene have been recently reported in individuals with MODY.

CONCLUSIONS

We diagnosed two patients with MODY using ES in children initially classified as "T1D". One has a likely pathogenic novel gene variant not previously associated with MODY. We demonstrate the clinical utility of ES in patients with clinical suspicion of MODY.

A Comprehensive Analysis of Hungarian MODY Patients-Part I: Gene Panel Sequencing Reveals Pathogenic Mutations in HNF1A, HNF1B, HNF4A, ABCC8 and INS Genes

Maturity-onset diabetes of the young (MODY) has about a dozen known causal genes to date, the most common ones being HNF1A, HNF4A, HNF1B and GCK. The phenotype of this clinically and genetically heterogeneous form of diabetes depends on the gene in which the patient has the mutation. We have tested 450 Hungarian index patients with suspected MODY diagnosis with Sanger sequencing and next-generation sequencing and found a roughly 30% positivity rate. More than 70% of disease-causing mutations were found in the GCK gene, about 20% in the HNF1A gene and less than 10% in other MODY-causing genes. We found 8 pathogenic and 9 likely pathogenic mutations in the HNF1A gene in a total of 48 patients and family members. In the case of HNF1A-MODY, the recommended first-line treatment is low dose sulfonylurea but according to our data, the majority of our patients had been on unnecessary insulin therapy at the time of requesting their genetic testing. Our data highlights the importance of genetic testing in the diagnosis of MODY and the establishment of the MODY subtype in order to choose the most appropriate treatment.

Challenges in the diagnosis of diabetes type in pediatrics

The incidence of diabetes, both type 1 and type 2, is increasing. Health outcomes in pediatric diabetes are currently poor, with trends indicating that they are worsening. Minority racial/ethnic groups are disproportionately affected by suboptimal glucose control and have a higher risk of acute and chronic complications of diabetes. Correct clinical management starts with timely and accurate classification of diabetes, but in children this is becoming increasingly challenging due to high prevalence of obesity and shifting demographic composition. The growing obesity epidemic complicates classification by obesity's effects on diabetes. Since the prevalence and clinical characteristics of diabetes vary among racial/ethnic groups, migration between countries leads to changes in the distribution of diabetes types in a certain geographical area, challenging the clinician's ability to classify diabetes. These challenges must be addressed to correctly classify diabetes and establish an appropriate treatment strategy early in the course of disease for all. This may be the first step in improving diabetes outcomes across racial/ethnic groups. This review will discuss the pitfalls in the current diabetes classification scheme that is leading to increasing overlap between diabetes types and heterogeneity within each type. It will also present proposed alternative classification schemes and approaches to understanding diabetes type that may improve the timely and accurate classification of pediatric diabetes type.

Failed Genetic Protection: Type 1 Diabetes in the Presence of HLA-DQB1*06:02

Certain HLA class II genes increase the risk for type 1 diabetes (T1D) development while others provide protection from disease development. HLA class II alleles encode MHC proteins on antigen-presenting cells, which function to present peptides and activate CD4 T cells. The DRB1*15:01 (DR15)-DQA1*01:02-DQB1*06:02 (DQ6) haplotype provides dominant protection across all stages of T1D and is a common haplotype found in Caucasians. However, it is present in <1% of people with T1D. Knowing which metabolic, immunologic, and genetic features are unique to individuals who fail genetic protection and develop T1D is important for defining the underlying mechanisms of DQB1*06:02-mediated protection. We describe a T1D cohort with DQB1*06:02 (n = 50) and compare them to individuals with T1D and without DQB1*06:02 (n = 2,759) who were identified over the last 26 years at the Barbara Davis Center for Diabetes. The age at diagnosis was similar between the cohorts and normally distributed throughout childhood and early adulthood. The average hemoglobin A_1c was 10.8 ± 2.8% (95 ± 7 mmol/mol) at diagnosis in those DQB1*06:02 positive. The majority of T1D DQB1*06:02 ⁺ individuals were positive for one or more islet autoantibodies; however, there was a greater proportion who were islet autoantibody negative compared with those T1D DQB1*06:02 ^- individuals. Interestingly, DQB1*03:02, which confers significant T1D risk, was present in only those DQB1*06:02 ⁺ individuals with islet autoantibodies. This is one of the largest studies examining patients presenting with clinical T1D in the presence of DQB1*06:02, which provides a population to study the mechanisms of failed genetic protection against T1D.

Molecular and clinical characteristics of monogenic diabetes mellitus in southern Chinese children with onset before 3 years of age

INTRODUCTION

A specific molecular diagnosis of monogenic diabetes mellitus (MDM) will help to predict the clinical course and guide management. This study aims to identify the causative genes implicated in Chinese patients with MDM with onset before 3 years of age.

RESEARCH DESIGN AND METHODS

71 children with diabetes mellitus (43 diagnosed before 6 months of age, and 28 diagnosed between 6 months and 3 years of age who were negative for diabetes-associated autoantibodies) underwent genetic testing with a combination strategy of Sanger sequencing, chromosome microarray analysis and whole exome sequencing. They were categorized into four groups according to the age of onset of diabetes (at or less than 6 months, 6 to 12 months, 1 to 2 years, 2 to 3 years) to investigate the correlation between genotype and phenotype.

RESULTS

Genetic abnormalities were identified in 39 of 71 patients (54.93%), namely KCNJ11 (22), ABCC8 (3), GCK (3), INS (3), BSCL2 (1) and chromosome abnormalities (7). The majority (81.40%, 35/43) of neonatal diabetes diagnosed less than 6 months of age and 33.33% (3/9) of infantile cases diagnosed between 6 and 12 months of age had a genetic cause identified. Only 11.11% (1/9) of cases diagnosed between 2 and 3 years of age were found to have a genetic cause, and none of the 10 patients diagnosed between 1 and 2 years had a positive result in the genetic analysis. Vast majority or 90.48% (19/21) of patients with KCNJ11 (19) or ABCC8 (2) variants had successful switch trial from insulin to oral sulfonylurea.

CONCLUSIONS

This study suggests that genetic testing should be given priority in diabetes cases diagnosed before 6 months of age, as well as those diagnosed between 6 and 12 months of age who were negative for diabetes-associated autoantibodies. This study also indicates significant impact on therapy with genetic cause confirmation.

Clinical and genetic analysis in a Chinese cohort of children and adolescents with diabetes/persistent hyperglycemia

Aims/Introduction

To investigate the genetic etiology and evaluate the diagnostic application of next‐generation sequencing for diabetes/persistent hyperglycemia in children and adolescents.

Materials and Methods

Patients with diabetes/persistent hyperglycemia, presenting with at least one other clinical manifestation (other than diabetes) or with a family history of diabetes, were recruited. The clinical and laboratory characteristics of the patients were recorded. Next‐generation sequencing was carried out, and candidate variants were verified by Sanger sequencing. Variant pathogenicity was further evaluated according to the American College of Medical Genetics and Genomics guidelines.

Results

This study included 101 potential probands, 36 of whom were identified as positive by genetic testing. A further 51.2 and 20.9% of variants were determined to be pathogenic or likely pathogenic, respectively. Variants associated with the disease were primarily identified in 21 genes and three regions of copy number variants. Among the 39 variants in 21 genes, 61.5% (24/39) were novel. The genetic diagnosis of 23 patients was confirmed based on genetic evidence and associated clinical manifestations. We reported GCK variants (21.7%, 5/23) as the most common etiology in our cohort. Different clinical manifestations were observed in one family with WFS1 variants.

Conclusions

Our findings support the use of next‐generation sequencing as a standard method in patients with diabetes/persistent hyperglycemia and provide insights into the etiologies of these conditions.

Genetics and Pathophysiology of Maturity-onset Diabetes of the Young (MODY): A Review of Current Trends

Single gene mutations have been implicated in the pathogenesis of a form of diabetes mellitus (DM) known as the maturity-onset diabetes of the young (MODY). However, there are diverse opinions on the suspect genes and pathophysiology, necessitating the need to review and communicate the genes to raise public awareness. We used the Google search engine to retrieve relevant information from reputable sources such as PubMed and Google Scholar. We identified 14 classified MODY genes as well as three new and unclassified genes linked with MODY. These genes are fundamentally embedded in the beta cells, the most common of which are HNF1A, HNF4A, HNF1B, and GCK genes. Mutations in these genes cause β-cell dysfunction, resulting in decreased insulin production and hyperglycemia. MODY genes have distinct mechanisms of action and phenotypic presentations compared with type 1 and type 2 DM and other forms of DM. Healthcare professionals are therefore advised to formulate drugs and treatment based on the causal genes rather than the current generalized treatment for all types of DM. This will increase the effectiveness of diabetes drugs and treatment and reduce the burden of the disease.

New clinical screening strategy to distinguish HNF1A variant-induced diabetes from young early-onset type 2 diabetes in a Chinese population

OBJECTIVE

Maturity-onset diabetes of the young caused by hepatocyte nuclear factor-1 alpha (HNF1A) variants (HNF1A-MODY) is a common form of monogenetic diabetes. Although patients with HNF1A-MODY might specifically benefit from sulfonylurea treatment, available methods for screening this specific type of diabetes are not cost-effective. This study was designed to establish an optimized clinical strategy based on multiple biomarkers to distinguish patients with HNF1A-MODY from clinically diagnosed early-onset type 2 diabetes (EOD) for genetic testing in a Chinese population.

RESEARCH DESIGN AND METHODS

A case-control study including 125 non-related young patients with EOD and 15 probands with HNF1A-MODY (cohort 1) was conducted to evaluate reported biomarkers for HNF1A-MODY. A cut-off for the fasting insulin (Fins) level, the 97.5 percentile of 150 healthy subjects with normal components of metabolic syndrome (cohort 2), was used to filter out individuals with obvious insulin resistance (Fins <102 pmol/L). An optimized clinical screening strategy (HNF1A-CSS) was established, and its effectiveness was assessed in another group of 410 young patients with EOD (cohort 3).

RESULTS

In cohort 1, body mass index (BMI), serum high-density lipoprotein cholesterol (HDL-c) and high-sensitivity C reactive protein (hs-CRP) levels were confirmed to be useful for the differential diagnosis of HNF1A-MODY. In cohort 3, eight probands with HNF1A-MODY were identified. In cohort 3 and young relatives with HNF1A-MODY, meeting three of four criteria (BMI <28 kg/m², hs-CRP <0.75 mg/L, Fins <102 pmol/L and HDL-c >1.12 mmol/L), the sensitivity and specificity of HNF1A-CSS were 100% and 69.3%, respectively. In the pooled analysis of all young patients, HNF1A-CSS displayed 90.5% sensitivity and 73.6% specificity for identifying patients with HNF1A-MODY among those with clinically diagnosed EOD.

CONCLUSION

Our HNF1A-CSS is useful for distinguishing patients with HNF1A-MODY from patients with EOD in a young Chinese population.

Review of current status of molecular diagnosis and characterization of monogenic diabetes mellitus: a focus on next-generation sequencing

Introduction: Monogenic diabetes is a subset of diabetes characterized by the presence of single-gene mutations and includes neonatal diabetes mellitus and maturity-onset diabetes of the young. Due to the genetic etiology of monogenic diabetes, molecular genetic testing can be used for diagnosis and classification.Areas covered: In addition to first-generation molecular analyses, many large clinical laboratories are transitioning to multiplexed next-generation sequencing panels to simultaneously assess patients for several of the most common genetic mutations seen in monogenic diabetes. With expanded development and adoption of next-generation sequencing panels, particularly in reference to laboratory settings, diagnostic testing for monogenic diabetes has the potential to be more accessible to the patient population.Expert opinion: Although molecular diagnostic testing is becoming increasingly prevalent, it is crucial to identify patients most likely to benefit from molecular testing versus those whose disease can be diagnosed and characterized with more traditional, less costly laboratory analyses. The continuous evolution of clinical molecular testing will be echoed in the clinical laboratory analysis of monogenic diabetes and continue to improve the diagnostic capabilities for monogenic diabetes mellitus.

Incidence and associates of diabetic ketoacidosis in a community-based cohort: the Fremantle Diabetes Study Phase II

OBJECTIVE

To assess the incidence and associates of diabetic ketoacidosis (DKA) in a representative community-based cohort.

METHODS

All hospitalizations of 1724 participants in the Fremantle Diabetes Study Phase II for/with DKA (plasma glucose >13.8 mmol/L, urinary/serum ketones, serum bicarbonate <18 mmol/L and/or arterial/venous pH <7.30) were identified between study entry from 2008 to 2011 and end-2013. Details of each episode were categorized by chart review as confirmed/probable DKA, possible DKA or not DKA. Incidence rates by diabetes type were calculated. Cox proportional hazards modeling determined predictors of first episode, and negative binomial regression identified predictors of frequency.

RESULTS

There were 53 coded DKA episodes (41 first episodes, 12 recurrences), of which 19 (35.8%) were incorrectly coded, 9 (17.0%) had possible DKA and 25 (47.2%) had confirmed/probable DKA. Of this latter group, 44% had type 1 diabetes, 32% had type 2 diabetes, 12% had latent autoimmune diabetes of adults (LADA) and 12% had secondary diabetes. The overall incidence of confirmed/probable DKA (95% CI) was 35.6 (23.0 to 52.6)/10 000 person-years (178.6 (85.7 to 328.5)/10 000 person-years for type 1 diabetes, 13.3 (5.7 to 26.1)/10 000 person-years for type 2 diabetes, 121.5 (33.1 to 311.0)/10 000 person-years for LADA and 446.5 (92.1 to 1304.9)/10 000 person-years for secondary diabetes). Baseline ln(fasting serum C-peptide) (inversely), glycated hemoglobin and secondary diabetes predicted both incident first confirmed/probable DKA episode and the frequency of DKA (p<0.001).

CONCLUSIONS

These data highlight the contribution of poor glycemic control and limited pancreatic beta cell function to incident DKA, and show that people with types of diabetes other than type 1, especially secondary diabetes, are at risk.

ABCC8-Related Maturity-Onset Diabetes of the Young (MODY12): A Report of a Chinese Family

Maturity-onset diabetes mellitus of the young (MODY) is a monogenic diabetes characterized by autosomal dominant inheritance. Its atypical clinical features make diagnosis difficult and it can be misdiagnosed as type 1 or type 2 diabetes. Fourteen subtypes of MODY have been diagnosed so far, of which MODY12 is caused by mutation of the ABCC8 (ATP Binding Cassette Subfamily C Member 8) gene, which is rarely reported in China. This paper reports a Chinese family of MODY12 caused by a rare missense mutation on the ABCC8 gene, which has not been reported to be associated with MODY in China or in other countries, with the aim of increasing clinicians' awareness and attention to the disease.

Update on clinical screening of maturity-onset diabetes of the young (MODY)

BACKGROUND

Maturity-onset diabetes of the young (MODY) is the most common type of monogenic diabetes, being characterized by beta-cell disfunction, early onset, and autosomal dominant inheritance. Despite the rapid evolution of molecular diagnosis methods, many MODY cases are misdiagnosed as type 1 or type 2 diabetes. High costs of genetic testing and limited knowledge of MODY as a relevant clinical entity are some of the obstacles that hinder correct MODY diagnosis and treatment. We present a broad review of clinical syndromes related to most common MODY subtypes, emphasizing the role of biomarkers that can help improving the accuracy of clinical selection of candidates for molecular diagnosis.

MAIN BODY

To date, MODY-related mutations have been reported in at least 14 different genes. Mutations in glucokinase (GCK), hepatocyte nuclear factor-1 homeobox A (HNF1A), and hepatocyte nuclear factor-4 homeobox A (HNF4A) are the most common causes of MODY. Accurate etiological diagnosis can be challenging. Many biomarkers such as apolipoprotein-M (ApoM), aminoaciduria, complement components, and glycosuria have been tested, but have not translated into helpful diagnostic tools. High-sensitivity C-reactive protein (hs-CRP) levels are lower in HNF1A-MODY and have been tested in some studies to discriminate HNF1A-MODY from other types of diabetes, although more data are needed. Overall, presence of pancreatic residual function and absence of islet autoimmunity seem the most promising clinical instruments to select patients for further investigation.

CONCLUSIONS

The selection of diabetic patients for genetic testing is an ongoing challenge. Metabolic profiling, diabetes onset age, pancreatic antibodies, and C-peptide seem to be useful tools to better select patients for genetic testing. Further studies are needed to define cut-off values in different populations.

How Recent Advances in Genomics Improve Precision Diagnosis and Personalized Care of Maturity-Onset Diabetes of the Young

PURPOSE OF REVIEW

Non-autoimmune monogenic diabetes (MD) in young people shows a broad spectrum of clinical presentations, which is largely explained by multiple genetic etiologies. This review discusses how the application of state-of-the-art genomics research to precision diagnosis of MD, particularly the various subtypes of maturity-onset diabetes of the young (MODY), has increasingly informed diabetes precision medicine and patient care throughout life.

RECENT FINDINGS

Due to extended genetic and clinical heterogeneity of MODY, diagnosis approaches based on next-generation sequencing have been worthwhile to better ascribe a specific subtype to each patient with young-onset diabetes. This guides the best appropriate treatment and clinical follow-up. Early etiological diagnosis of MD and individualized treatment are essential for achieving metabolic targets and avoiding long-term diabetes complications, as well as for drastically decreasing the financial and societal burden of diabetes-related healthcare. Genomic medicine-based practices help to optimize long-term clinical follow-up and patient care management.

Negative autoimmunity in a Spanish pediatric cohort suspected of type 1 diabetes, could it be monogenic diabetes?

Objective

Monogenic diabetes can be misdiagnosed as type 1 or type 2 diabetes in children. The right diagnosis is crucial for both therapeutic choice and prognosis and influences genetic counseling. The main objective of this study was to search for monogenic diabetes in Spanish pediatric patients suspected of type 1 diabetes with lack of autoimmunity at the onset of the disease. We also evaluated the extra value of ZnT8A in addition to the classical IAA, GADA and IA2A autoantibodies to improve the accuracy of type 1 diabetes diagnosis.

Methods

Four hundred Spanish pediatric patients with recent-onset diabetes (mean age 8.9 ± 3.9 years) were analyzed for IAA, GADA, IA2A and ZnT8A pancreatic-autoantibodies and HLA-DRB1 alleles. Patients without autoimmunity and those with only ZnT8A positive were screened for 12 monogenic diabetes genes by next generation sequencing.

Results

ZnT8A testing increased the number of autoantibody-positive patients from 373 (93.3%) to 377 (94.3%). An isolated positivity for ZnT8A allowed diagnosing autoimmune diabetes in 14.8% (4/27) of pediatric patients negative for the rest of the antibodies tested. At least 2 of the 23 patients with no detectable autoimmunity (8%) carried heterozygous pathogenic variants: one previously reported missense variant in the INS gene (p.Gly32Ser) and one novel frameshift variant (p.Val264fs) in the HNF1A gene. One variant of uncertain significance was also found. Carriers of pathogenic variants had HLA-DRB1 risk alleles for autoimmune diabetes and clinical characteristics compatible with type 1 diabetes except for the absence of autoimmunity.

Conclusion

ZnT8A determination improves the diagnosis of autoimmune diabetes in pediatrics. At least 8% of pediatric patients suspected of type 1 diabetes and with undetectable autoimmunity have monogenic diabetes and can benefit from the correct diagnosis of the disease by genetic study.

Autoantibodies against ZnT8 are rare in Central-European LADA patients and absent in MODY patients, including those positive for other autoantibodies

BACKGROUND

Testing for autoantibodies against the zinc transporter ZnT8 (ZnTA) is becoming routine in pediatric diabetes. However, available data are inconclusive when focusing on adult-onset diabetes, including autoimmune diabetes, which does not require insulin at diagnosis (LADA).

BASIC PROCEDURES

We examined the ZnTA prevalence and titers and matched them with the clinical phenotype and PTPN22 genotypes of Czech LADA patients who were positive for GADA and/or IA2A and had a fasting C-peptide level >200 pmol/L at diagnosis as well as HNF4A-, GCK- or HNF1A-MODY patients and healthy controls.

MAIN FINDINGS

Most LADA patients were negative for ZnTA, and the sensitivity of the assay was only 18-20% for patients with LADA-like progression to insulinotherapy compared to healthy controls. In LADA patients, there was no association between the ZnTA and PTPN22 risk genotypes. LADA patients positive for ZnTA had a lower BMI than those positive for other autoantibodies alone. Importantly, MODY patients were completely negative for ZnTA, and the levels of ZnTA in MODY patients were similar to those in healthy controls.

CONCLUSIONS

ZnTA quantification did not improve LADA diagnosis. However, positivity for ZnTA can be used as a negative MODY pre-diagnostic criterion even in the region of Central and East Europe, where other islet cell autoantibodies are common in MODY patients.

Maturity Onset Diabetes of the Young – An Overview of Common Types. A Review

Background and aims: Maturity Onset diabetes in Young (MODY) is an autosomal dominant disease and according to an estimate, the MODY cases are 2% of all the diabetic cases. The objective was to review the common types of MODY reported in literature in context to their geographical areas. Material and method: For literature search, PubMed data base was used. The key word was “Maturity onset diabetes of the young”. The articles were reviewed by titles and if found relevant, the abstract and full article (if available) were retrieved. The studies that were published in English, presented original data and describe type of MODY were included. The information related to author, year of publication and type of MODY was extracted in excel sheet. Results: A total of 1135 studies resulted which were reviewed, and 206 articles were finally selected. The studies were grouped according to the regions i.e. Asia, Europe, America, Africa and Australia & Oceania. The MODY 2 was most prevalent in regions i.e. Asia, Europe, America and Australia & Oceania followed by MODY 3. When analysed according to countries, MODY 2 was found prevalent in India, Korea, UK, Italy, Spain, Czech Republic, Canada and Brazil while MODY 3 was common in Japan, China, France Norway and Germany. Conclusion: The MODY 2 was most common. The data from south Asian countries including Pakistan is lacking. As there is a huge burden of diabetes in the country so there is a dire need to do large scale studies on MODY in the country.

Monogenic Diabetes in Children and Adolescents: Recognition and Treatment Options

PURPOSE OF REVIEW

We provide a review of monogenic diabetes in young children and adolescents with a focus on recognition, management, and pharmacological treatment.

RECENT FINDINGS

Monogenic forms of diabetes account for approximately 1-2% of diabetes in children and adolescents, and its incidence has increased in recent years due to greater awareness and wider availability of genetic testing. Monogenic diabetes is due to single gene defects that primarily affect beta cell function with more than 30 different genes reported. Children with antibody-negative, C-peptide-positive diabetes should be evaluated and genetically tested for monogenic diabetes. Accurate genetic diagnosis impacts treatment in the most common types of monogenic diabetes, including the use of sulfonylureas in place of insulin or other glucose-lowering agents or discontinuing pharmacologic treatment altogether. Diagnosis of monogenic diabetes can significantly improve patient care by enabling prediction of the disease course and guiding appropriate management and treatment.

Monogenic diabetes in overweight and obese youth diagnosed with type 2 diabetes: the TODAY clinical trial

PurposeMonogenic diabetes accounts for 1-2% of diabetes cases. It is often undiagnosed, which may lead to inappropriate treatment. This study was performed to estimate the prevalence of monogenic diabetes in a cohort of overweight/obese adolescents diagnosed with type 2 diabetes (T2D).MethodsSequencing using a custom monogenic diabetes gene panel was performed on a racially/ethnically diverse cohort of 488 overweight/obese adolescents with T2D in the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) clinical trial. Associations between having a monogenic diabetes variant and clinical characteristics and time to treatment failure were analyzed.ResultsMore than 4% (22/488) had genetic variants causing monogenic diabetes (seven GCK, seven HNF4A, five HNF1A, two INS, and one KLF11). Patients with monogenic diabetes had a statistically, but not clinically, significant lower body mass index (BMI) z-score, lower fasting insulin, and higher fasting glucose. Most (6/7) patients with HNF4A variants rapidly failed TODAY treatment across study arms (hazard ratio = 5.03, P = 0.0002), while none with GCK variants failed treatment.ConclusionThe finding of 4.5% of patients with monogenic diabetes in an overweight/obese cohort of children and adolescents with T2D suggests that monogenic diabetes diagnosis should be considered in children and adolescents without diabetes-associated autoantibodies and maintained C-peptide, regardless of BMI, as it may direct appropriate clinical management.

Fifteen-minute consultation: Monogenic forms of diabetes with onset after age 6 months

Monogenic forms of diabetes (historically known as Maturity Onset Diabetes of the Young (MODY)) are caused by single gene mutations inherited in an autosomal dominant fashion that result in reduced pancreatic beta cell function. Children with these forms of diabetes may be misdiagnosed as having type 1 or 2 diabetes, which has important implications for treatment, genetic counselling, screening of family members and prognosis. Useful tools now exist to aid in their diagnosis and management. Here, we attempt to outline the clinical features that will help the physician make the differentiation from other diabetes subtypes.

Gene silencing of ZnT8 attenuates inflammation and protects pancreatic tissue injury in T1D

T lymphocyte mediated inflammation contributes to the development of T1D. Zinc Transporter 8 (ZnT8) has emerged as a target of autoreactive T cells in human T1D in recent years. However, the regulating of ZnT8 in T1D has not been identified. We make a hypothesis that whether alternation of ZnT8 level could attenuate inflammation and protect pancreatic tissue injury in T1D. In this study, we utilized ZnT8 shRNA to inhibit ZnT8 expression, and detected inflammation, glucose tolerance and pancreatic tissue of NOD mice. We found that ZnT8 shRNA attenuated specific CD8+ T cell activation and cytotoxicity. In addition, ZnT8 shRNA protected glucose tolerance and pancreatic tissue injury via down-regulation of ZnT8 in NOD mice. Therefore, the results suggest that RNAi represents a promising target reducing ZnT8 mediated inflammation, and provides a novel therapeutical clue in T1D.

Can Biomarkers Help Target Maturity-Onset Diabetes of the Young Genetic Testing in Antibody-Negative Diabetes?

BACKGROUND

Maturity-onset diabetes of the young (MODY) is an antibody-negative, autosomal dominant form of diabetes. With the increasing prevalence of diabetes and the expense of MODY testing, markers to identify those who need further genetic testing would be beneficial. We investigated whether HLA genotypes, random C-peptide, and/or high-sensitivity C-reactive protein (hsCRP) levels could be helpful biomarkers for identifying MODY in antibody-negative diabetes.

METHODS

Subjects (N = 97) with diabetes onset ≤age 25, measurable C-peptide (≥0.1 ng/mL), and negative for all four diabetes autoantibodies were enrolled at a large academic center and tested for MODY 1-5 through Athena Diagnostics. A total of 22 subjects had a positive or very likely pathogenic mutation for MODY.

RESULTS

Random C-peptide levels were significantly different between MODY-positive and MODY-negative subjects (0.16 nmol/L vs. 0.02 nmol/L; P = 0.02). After adjusting for age and diabetes duration, hsCRP levels were significantly lower in MODY-positive subjects (0.37 mg/L vs. 0.87 mg/L; P = 0.02). Random C-peptide level ≥0.15 nmol/L obtained at ≥6 months after diagnosis had 83% sensitivity for diagnosis of MODY with a negative predictive value of 96%. Receiver operating characteristic curves showed that area under the curve for random C-peptide (0.75) was significantly better than hsCRP (0.54), high-risk HLA DR3/4-DQB1*0302 (0.59), and high-risk HLA/random C-peptide combined (0.54; P = 0.03).

CONCLUSIONS

Random C-peptide obtained at ≥6 months after diagnosis can be a useful biomarker to identify antibody-negative individuals who need further genetic testing for MODY, whereas hsCRP and HLA do not appear to improve this antibody/C-peptide-based approach.

Spectrum of mutations in monogenic diabetes genes identified from high-throughput DNA sequencing of 6888 individuals

BACKGROUND

Diagnosis of monogenic as well as atypical forms of diabetes mellitus has important clinical implications for their specific diagnosis, prognosis, and targeted treatment. Single gene mutations that affect beta-cell function represent 1-2% of all cases of diabetes. However, phenotypic heterogeneity and lack of family history of diabetes can limit the diagnosis of monogenic forms of diabetes. Next-generation sequencing technologies provide an excellent opportunity to screen large numbers of individuals with a diagnosis of diabetes for mutations in disease-associated genes.

METHODS

We utilized a targeted sequencing approach using the Illumina HiSeq to perform a case-control sequencing study of 22 monogenic diabetes genes in 4016 individuals with type 2 diabetes (including 1346 individuals diagnosed before the age of 40 years) and 2872 controls. We analyzed protein-coding variants identified from the sequence data and compared the frequencies of pathogenic variants (protein-truncating variants and missense variants) between the cases and controls.

RESULTS

A total of 40 individuals with diabetes (1.8% of early onset sub-group and 0.6% of adult onset sub-group) were carriers of known pathogenic missense variants in the GCK, HNF1A, HNF4A, ABCC8, and INS genes. In addition, heterozygous protein truncating mutations were detected in the GCK, HNF1A, and HNF1B genes in seven individuals with diabetes. Rare missense mutations in the GCK gene were significantly over-represented in individuals with diabetes (0.5% carrier frequency) compared to controls (0.035%). One individual with early onset diabetes was homozygous for a rare pathogenic missense variant in the WFS1 gene but did not have the additional phenotypes associated with Wolfram syndrome.

CONCLUSION

Targeted sequencing of genes linked with monogenic diabetes can identify disease-relevant mutations in individuals diagnosed with type 2 diabetes not suspected of having monogenic forms of the disease. Our data suggests that GCK-MODY frequently masquerades as classical type 2 diabetes. The results confirm that MODY is under-diagnosed, particularly in individuals presenting with early onset diabetes and clinically labeled as type 2 diabetes; thus, sequencing of all monogenic diabetes genes should be routinely considered in such individuals. Genetic information can provide a specific diagnosis, inform disease prognosis and may help to better stratify treatment plans.

Using Personalized Medicine in the Management of Diabetes Mellitus

Diabetes mellitus is a worldwide problem with an immense pharmacoeconomic burden. The multifactorial and complex nature of the disease lends itself to personalized pharmacotherapeutic approaches to treatment. Variability in individual risk and subsequent development of diabetes has been reported in addition to differences in response to the many oral glucose lowering therapies currently available for diabetes pharmacotherapy. Pharmacogenomic studies have attempted to uncover the heritable components of individual variability in risk susceptibility and response to pharmacotherapy. We review the current pharmacogenomics evidence as it relates to common oral glucose lowering therapies and how they can be utilized in the management of polygenic and monogenic forms of diabetes. Evidence supports the use of genetic testing and personalized approaches to the treatment of monogenic diabetes of the young. The data are not as robust for the current application of pharmacogenetic approaches to the treatment of polygenic type 2 diabetes mellitus, but there are suggestions as to future applications in this regard. We reviewed pertinent primary literature sources as well as current evidence-based guidelines on diabetes management.

Population-Based Assessment of a Biomarker-Based Screening Pathway to Aid Diagnosis of Monogenic Diabetes in Young-Onset Patients

OBJECTIVE

Monogenic diabetes, a young-onset form of diabetes, is often misdiagnosed as type 1 diabetes, resulting in unnecessary treatment with insulin. A screening approach for monogenic diabetes is needed to accurately select suitable patients for expensive diagnostic genetic testing. We used C-peptide and islet autoantibodies, highly sensitive and specific biomarkers for discriminating type 1 from non-type 1 diabetes, in a biomarker screening pathway for monogenic diabetes.

RESEARCH DESIGN AND METHODS

We studied patients diagnosed at age 30 years or younger, currently younger than 50 years, in two U.K. regions with existing high detection of monogenic diabetes. The biomarker screening pathway comprised three stages: 1) assessment of endogenous insulin secretion using urinary C-peptide/creatinine ratio (UCPCR); 2) if UCPCR was ≥0.2 nmol/mmol, measurement of GAD and IA2 islet autoantibodies; and 3) if negative for both autoantibodies, molecular genetic diagnostic testing for 35 monogenic diabetes subtypes.

RESULTS

A total of 1,407 patients participated (1,365 with no known genetic cause, 34 with monogenic diabetes, and 8 with cystic fibrosis-related diabetes). A total of 386 out of 1,365 (28%) patients had a UCPCR ≥0.2 nmol/mmol, and 216 out of 386 (56%) were negative for GAD and IA2 and underwent molecular genetic testing. Seventeen new cases of monogenic diabetes were diagnosed (8 common Maturity Onset Diabetes of the Young [Sanger sequencing] and 9 rarer causes [next-generation sequencing]) in addition to the 34 known cases (estimated prevalence of 3.6% [51/1,407] [95% CI 2.7-4.7%]). The positive predictive value was 20%, suggesting a 1-in-5 detection rate for the pathway. The negative predictive value was 99.9%.

CONCLUSIONS

The biomarker screening pathway for monogenic diabetes is an effective, cheap, and easily implemented approach to systematically screening all young-onset patients. The minimum prevalence of monogenic diabetes is 3.6% of patients diagnosed at age 30 years or younger.

Towards a systematic nationwide screening strategy for MODY

MODY is an early-onset monogenic form of diabetes. Correctly identifying MODY is of considerable importance as diagnosing the specific genetic subtype can inform the optimal treatment, with many patients being able to discontinue unnecessary insulin treatment. Diagnostic molecular genetic testing to confirm MODY is expensive, so screening strategies are required to identify the most appropriate patients for testing. In this issue of Diabetologia, Johansson and colleagues (DOI 10.1007/s00125-016-4167-1 ) describe a nationwide systematic screening approach to identify individuals with MODY in the paediatric age range. They focused testing on patients negative for both GAD and islet antigen 2 (IA-2) islet autoantibodies, thereby ruling out those with markers of type 1 diabetes, the most common form of diabetes in this age group. This commentary discusses the advantages and limitations of the approach, and the caution required when interpreting variants of uncertain pathogenicity identified from testing whole populations rather than targeting only patients with a strong MODY phenotype.

Systematic Population Screening, Using Biomarkers and Genetic Testing, Identifies 2.5% of the U.K. Pediatric Diabetes Population With Monogenic Diabetes

OBJECTIVE

Monogenic diabetes is rare but is an important diagnosis in pediatric diabetes clinics. These patients are often not identified as this relies on the recognition of key clinical features by an alert clinician. Biomarkers (islet autoantibodies and C-peptide) can assist in the exclusion of patients with type 1 diabetes and allow systematic testing that does not rely on clinical recognition. Our study aimed to establish the prevalence of monogenic diabetes in U.K. pediatric clinics using a systematic approach of biomarker screening and targeted genetic testing.

RESEARCH DESIGN AND METHODS

We studied 808 patients (79.5% of the eligible population) <20 years of age with diabetes who were attending six pediatric clinics in South West England and Tayside, Scotland. Endogenous insulin production was measured using the urinary C-peptide creatinine ratio (UCPCR). C-peptide-positive patients (UCPCR ≥0.2 nmol/mmol) underwent islet autoantibody (GAD and IA2) testing, with patients who were autoantibody negative undergoing genetic testing for all 29 identified causes of monogenic diabetes.

RESULTS

A total of 2.5% of patients (20 of 808 patients) (95% CI 1.6-3.9%) had monogenic diabetes (8 GCK, 5 HNF1A, 4 HNF4A, 1 HNF1B, 1 ABCC8, 1 INSR). The majority (17 of 20 patients) were managed without insulin treatment. A similar proportion of the population had type 2 diabetes (3.3%, 27 of 808 patients).

CONCLUSIONS

This large systematic study confirms a prevalence of 2.5% of patients with monogenic diabetes who were <20 years of age in six U.K. clinics. This figure suggests that ∼50% of the estimated 875 U.K. pediatric patients with monogenic diabetes have still not received a genetic diagnosis. This biomarker screening pathway is a practical approach that can be used to identify pediatric patients who are most appropriate for genetic testing.

Assessment of Newly Proposed Clinical Criteria to Identify HNF1A MODY in Patients with an Initial Diagnosis of Type 1 or Type 2 Diabetes Mellitus

The most common form of maturity-onset diabetes of the young (MODY) is caused by mutations in the hepatocyte nuclear factor 1A (HNF1A) gene. However, most HNF1A mutation-carriers are initially misdiagnosed with type 1 (T1DM) or type 2 (T2DM) diabetes mellitus; hence, they often receive nonoptimal treatment. The aim of our study was to test newly proposed clinical criteria for the identification of HNF1A MODY in patients with a diagnosis of T1DM or T2DM. To achieve this, the following criteria to preselect patients for screening were used: for T1DM: TDIR (total daily insulin requirement) > 0.3 IU of insulin/kg and the percentage of basal insulin > 30% of TDIR; for T2DM: sulphonylurea- (SU-) based oral treatment (monotherapy or combined with Metformin) > 15 years and BMI < 30 kg/m(2). We reviewed the clinical data of 140 patients with T1DM and 524 clinically diagnosed with T2DM. On the basis of these criteria, we found a HNF1A mutation in 1 out of 2 individuals with a diagnosis of T1DM and 1 out of 11 selected individuals with a diagnosis of T2DM. We believe that the simplicity of the proposed criteria might prove useful in clinical practice, as an alternative to more time-consuming classical diagnostic techniques.

Undiagnosed MODY: Time for Action

Maturity-onset diabetes of the young (MODY) is a monogenic form of diabetes that accounts for at least 1 % of all cases of diabetes mellitus. MODY classically presents as non-insulin-requiring diabetes in lean individuals typically younger than 25 with evidence of autosomal dominant inheritance, but these criteria do not capture all cases and can also overlap with other diabetes types. Genetic diagnosis of MODY is important for selecting the right treatment, yet ~95 % of MODY cases in the USA are misdiagnosed. MODY prevalence and characteristics have been well-studied in some populations, such as the UK and Norway, while other ethnicities, like African and Latino, need much more study. Emerging next-generation sequencing methods are making more widespread study and clinical diagnosis increasingly feasible; at the same time, they are detecting other mutations in the same genes of unknown clinical significance. This review will cover the current epidemiological studies of MODY and barriers and opportunities for moving toward a goal of access to an appropriate diagnosis for all affected individuals.