Maturity-onset diabetes of the young (MODY): how many cases are we missing?

Clinical and functional characterization of a novel KCNJ11 (c.101G > A, p.R34H) mutation associated with maturity-onset diabetes mellitus of the young type 13

PURPOSE

This study aimed to describe the clinical features, diagnostic and therapeutic course of a patient with MODY13 caused by KCNJ11 (c.101G > A, p.R34H) and how it contributes to the pathogenesis of MODY13, and to explore new therapeutic targets.

METHODS

Whole-exome sequencing was used to screen prediagnosed individuals and family members with clinically suspected KCNJ11 mutations. Real-time fluorescence quantitative PCR, western blotting, thallium flux of potassium channels, glucose-stimulated insulin secretion (GSIS), and immunofluorescence assays were used to analyze the regulation of insulin secretion by the KCNJ11 mutant in MIN6 cells. Daily blood glucose levels were continuously monitored for 14 days in the proband using the ambulatory blood glucose meter (SIBIONICS).

RESULTS

Mutation screening of the entire exon of the gene identified a heterozygous KCNJ11 (c.101G > A, p.R34H) mutation in the proband and his mother. Cell-based GSIS assays after transfection of MIN6 using wild-type and mutant plasmids revealed that this mutation impaired insulin secretory function. Furthermore, we found that this impaired secretory function is associated with reduced functional activity of the mutant KCNJ11 protein and reduced expression of the insulin secretion-associated exocytosis proteins STXBP1 and SNAP25.

CONCLUSION

For the first time, we revealed the pathogenic mechanism of KCNJ11 (c.101G > A, p.R34H) associated with MODY13. This mutant can cause alterations in KATP channel activity, reduce sensitivity to glucose stimulation, and impair pancreatic β-cell secretory function by downregulating insulin secretion-associated exocytosis proteins. Therefore, oral sulfonylurea drugs can lower blood glucose levels through pro-insulinotropic effects and are more favorable for patients with this mutation.

Case report: A novel HNF1A variant linked to gestational diabetes, congenital hyperinsulinism, and diazoxide hypersensitivity

Diazoxide (DZX) remains the first-line medication for the treatment of prolonged and persistent forms of hyperinsulinemic hypoglycemia (HH). In nearly 40%-50% of cases of HH, the genetic mechanism is unidentified. Almost half of the infants with permanent or genetic causes are DZX sensitive, but hypersensitivity to DZX is extremely rare, and the mechanism is poorly understood. Here, we report for the first time a case of DZX hypersensitivity in a neonate with HH who inherited a novel HNF1A variant from the mother. A term, male large-for-gestational-age infant of a diabetic mother presented with early onset of severe, recurrent hypoglycemia. Critical blood samples when hypoglycemic confirmed HH. Diazoxide was initiated at conventional doses of 5 mg/kg/day, which resulted in hyperglycemia (blood glucose, 16.6 mmol/L) within 48 h. Glucose infusion was rapidly weaned off. DZX was withheld and eventually stopped. Following 3 days of milk feeds alone with a normal glucose profile, suspecting a resolution of HH, he underwent a 6-h fasting study and passed. While on glucose monitoring in the hospital, he again developed hypoglycemic episodes, and the critical blood samples confirmed HH. DZX was restarted at a lower dose of 3 mg/kg/day, which required further down-titration to 0.7 mg/kg/day before steady euglycemia was obtained. No more episodes of hypo- or hyperglycemia occurred, and he passed a safety fasting study before discharge. Molecular genetic testing identified a novel HNF1A mutation in the mother-child dyad, whereas the father tested negative. We concluded that the HH phenotype due to this novel HNF1A mutation can be mutation specific and require a very low dose of DZX. Clinicians should observe closely for the risk of diabetic ketoacidosis and hyperglycemic hyperosmolar state while initiating DZX therapy.

Ciliopathies are responsible for short stature and insulin resistance: A systematic review of this clinical association regarding SOFT syndrome

SOFT syndrome (Short stature-Onychodysplasia-Facial dysmorphism-hypoTrichosis) is a rare primordial dwarfism syndrome caused by biallelic variants in POC1A encoding a centriolar protein. To refine the phenotypic spectrum of SOFT syndrome, recently shown to include metabolic features, we conducted a systematic review of all published cases (19 studies, including 42 patients). The SOFT tetrad affected only 24 patients (57%), while all cases presented with short stature from birth (median height: -5.5SDS([-8.5]-[-2.8])/adult height: 132.5 cm(103.5-148)), which was most often disproportionate (90.5%), with relative macrocephaly. Bone involvement resulted in short hands and feet (100%), brachydactyly (92.5%), metaphyseal (92%) or epiphyseal (84%) anomalies, and/or sacrum/pelvis hypoplasia (58%). Serum IGF-I was increased (median IGF-I level: + 2 SDS ([-0.5]-[+ 3])). Recombinant human growth hormone (rhGH) therapy was stopped for absence/poor growth response (7/9 patients, 78%) and/or hyperglycemia (4/9 patients, 45%). Among 11 patients evaluated, 10 (91%) presented with central distribution of fat (73%), clinical (64%) and/or biological insulin resistance (IR) (100%, median HOMA-IR: 18), dyslipidemia (80%), and hepatic steatosis (100%). Glucose tolerance abnormalities affected 58% of patients aged over 10 years. Patients harbored biallelic missense (52.4%) or truncating (45.2%) POC1A variants. Biallelic null variants, affecting 36% of patients, were less frequently associated with the SOFT tetrad (33% vs 70% respectively, p = 0.027) as compared to other variants, without difference in the prevalence of metabolic abnormalities. POC1A should be sequenced in children with short stature, altered glucose/insulin homeostasis and/or centripetal fat distribution. In patients with SOFT syndrome, rhGH treatment is not indicated, and IR-related complications should be regularly screened and monitored.PROSPERO registration: CRD42023460876.

Course of pregnancy and 10-year observation of twins diagnosed with GCK-MODY in the neonatal period: a case report

Monogenic diabetes accounts for 5% of all incidence of hyperglycemia and Maturity Onset Diabetes of the Young (MODY) is the most common form. In GCK-MODY, one of the most common forms of MODY, hyperglycemia is caused by a mutation of a gene responsible for coding glucokinase. At the clinical level, this condition presents as persistent, moderate and asymptomatic elevated fasting glucose levels and has a relatively low incidence of micro and macro-vascular complications. In general, the treatment of choice is to follow and maintain a healthy lifestyle. The incidence of GCK-MODY during pregnancy is 2% on average (0-6%). In this report, we introduce a case of a woman diagnosed with GCK-MODY during the pregnancy with twins, a boy and a girl, diagnosed with GCK-MODY after birth. We discuss the course of pregnancy, the need for access to fast and uncomplicated genetic diagnostics in utero, and the impact of the MODY diagnosis on the life of the mother and that of her children. In our case, the diagnosis of GCK-MODY was associated with a feeling of relief, after years of uncertainty, and helped to introduce more appropriate eating behaviors and lifestyle changes for both the mother and her children.

Monogenic Defects of Beta Cell Function: From Clinical Suspicion to Genetic Diagnosis and Management of Rare Types of Diabetes

Monogenic defects of beta cell function refer to a group of rare disorders that are characterized by early-onset diabetes mellitus due to a single gene mutation affecting insulin secretion. It accounts for up to 5% of all pediatric diabetes cases and includes transient or permanent neonatal diabetes, maturity-onset diabetes of the young (MODY), and various syndromes associated with diabetes. Causative mutations have been identified in genes regulating the development or function of the pancreatic beta cells responsible for normal insulin production and/or release. To date, more than 40 monogenic diabetes subtypes have been described, with those caused by mutations in HNF1A and GCK genes being the most prevalent. Despite being caused by a single gene mutation, each type of monogenic diabetes, especially MODY, can appear with various clinical phenotypes, even among members of the same family. This clinical heterogeneity, its rarity, and the fact that it shares some features with more common types of diabetes, can make the clinical diagnosis of monogenic diabetes rather challenging. Indeed, several cases of MODY or syndromic diabetes are accurately diagnosed in adulthood, after having been mislabeled as type 1 or type 2 diabetes. The recent widespread use of more reliable sequencing techniques has improved monogenic diabetes diagnosis, which is important to guide appropriate treatment and genetic counselling. The current review aims to summarize the latest knowledge on the clinical presentation, genetic confirmation, and therapeutic approach of the various forms of monogenic defects of beta cell function, using three imaginary clinical scenarios and highlighting clinical and laboratory features that can guide the clinician in reaching the correct diagnosis.

Modelling human diabetes ex vivo: a glance at maturity onset diabetes of the young

Diabetes is a complex metabolic disease which most commonly has a polygenic origin; however, in rare cases, diabetes may be monogenic. This is indeed the case in both Maturity Onset Diabetes of the Young (MODY) and neonatal diabetes. These disease subtypes are believed to be simpler than Type 1 (T1D) and Type 2 Diabetes (T2D), which allows for more precise modelling. During the three last decades, many studies have focused on rodent models. These investigations provided a wealth of knowledge on both pancreas development and beta cell function. In particular, they allowed the establishment of a hierarchy of the transcription factors and highlighted the role of microenvironmental factors in the control of progenitor cell proliferation and differentiation. Transgenic mice also offered the possibility to decipher the mechanisms that define the functional identity of the pancreatic beta cells. Despite such interest in transgenic mice, recent data have also indicated that important differences exist between mice and human. To overcome these limitations, new human models are necessary. In the present review, we describe these ex vivo models, which are created using stem cells and organoids, and represent an important step toward islet cell therapy and drug discovery.

A New Tool to Identify Pediatric Patients with Atypical Diabetes Associated with Gene Polymorphisms

BACKGRUOUND

Recent diabetes subclassifications have improved the differentiation between patients with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus despite several overlapping features, yet without considering genetic forms of diabetes. We sought to facilitate the identification of monogenic diabetes by creating a new tool that we validated in a pediatric maturity-onset diabetes of the young (MODY) cohort.

METHODS

We first created the DIAgnose MOnogenic DIAbetes (DIAMODIA) criteria based on the pre-existing, but incomplete, MODY calculator. This new score is composed of four strong and five weak criteria, with patients having to display at least one weak and one strong criterion.

RESULTS

The effectiveness of the DIAMODIA criteria was evaluated in two patient cohorts, the first consisting of patients with confirmed MODY diabetes (n=34) and the second of patients with T1DM (n=390). These DIAMODIA criteria successfully detected 100% of MODY patients. Multiple correspondence analysis performed on the MODY and T1DM cohorts enabled us to differentiate MODY patients from T1DM. The three most relevant variables to distinguish a MODY from T1DM profile were: lower insulin-dose adjusted A1c score ≤9, glycemic target-adjusted A1c score ≤4.5, and absence of three anti-islet cell autoantibodies.

CONCLUSION

We validated the DIAMODIA criteria, as it effectively identified all monogenic diabetes patients (MODY cohort) and succeeded to differentiate T1DM from MODY patients. The creation of this new and effective tool is likely to facilitate the characterization and therapeutic management of patients with atypical diabetes, and promptly referring them for genetic testing which would markedly improve clinical care and counseling, as well.

High prevalence of copy number variations in the Japanese participants with suspected MODY

Maturity-Onset Diabetes of the Young (MODY) is a diabetes mellitus subtype caused by a single gene. The detection rate of the responsible gene is 27% in the United Kingdom, indicating that the causative gene remains unknown in the majority of clinically diagnosed MODY cases. To improve the detection rate, we applied comprehensive genetic testing using whole exome sequencing (WES) followed by Multiplex Ligation-dependent Probe Amplification (MLPA) and functional analyses. Twenty-one unrelated Japanese participants with MODY were enrolled in the study. To detect copy number variations (CNVs), WES was performed first, followed by MLPA analysis for participants who were negative on the basis of WES. Undetermined variants were analyzed according to their functional properties. WES identified 7 pathogenic and 3 novel likely pathogenic variants in the 21 participants. Functional analyses revealed that 1 in 3 variants was pathogenic. MLPA analysis applied to the remaining 13 undetermined samples identified 4 cases with pathogenic CNVs: 3 in HNF4A and 1 in HNF1B. Pathogenic variants were identified in 12 participants (12/21, 57.1%) - relatively high rate reported to date. Notably, one-third of the participants had CNVs in HNF4A or HNF1B, indicating a limitation of WES-only screening.

Monogenic Diabetes: A Comprehensive Overview and Therapeutic Management of Subtypes of Mody

BACKGROUND

Monogenic diabetes often occurs as a result of single-gene mutations. The illness is minimally affected by environmental and behavioral factors, and it constitutes around one to five percent of all cases of diabetes.

METHODS

Newborn diabetes mellitus (NDM) and maturity-onset diabetes of the young (MODY) are the predominant causes of monogenic diabetes, accounting for a larger proportion of cases, while syndromic diabetes represents a smaller percentage. MODY, a group of inherited non-autoimmune diabetes mellitus disorders, is quite common. However, it remains frequently misdiagnosed despite increasing public awareness. The condition is characterized by insulin resistance, the development of diabetes at a young age (before 25 years), mild high blood sugar levels, inheritance in an autosomal dominant pattern, and the preservation of natural insulin production.

RESULTS

Currently, there are 14 distinct subtypes of MODY that have been identified. Each subtype possesses distinct characteristics in terms of their frequency, clinical symptoms, severity of diabetes, related complications, and response to medicinal interventions. Due to the clinical similarities, lack of awareness, and high expense of genetic testing, distinguishing between type I (T1D) and type II diabetes mellitus (T2D) can be challenging, resulting in misdiagnosis of this type of diabetes. As a consequence, a significant number of individuals are being deprived of adequate medical attention. Accurate diagnosis enables the utilization of novel therapeutic strategies and enhances the management of therapy in comparison to type II and type I diabetes.

CONCLUSION

This article offers a concise overview of the clinical subtypes and characteristics of monogenic diabetes. Furthermore, this article discusses the various subtypes of MODY, as well as the process of diagnosing, managing, and treating the condition. It also addresses the difficulties encountered in detecting and treating MODY.

A case series of maturity-onset diabetes of the young highlighting atypical presentations and the implications of genetic diagnosis

Maturity-onset diabetes of the young (MODY) is a clinically heterogeneous group of monogenic diabetes characterized by onset at a young age and an autosomal dominant mode of inheritance. Notably, MODY accounts for 2%-5% of all diabetes cases, and its distinction from types 1 (T1DM) and 2 (T2DM) diabetes mellitus is often challenging. We report herein the cases of two girls and a boy who presented initially with diabetic ketoacidosis. In view of the strong family history of diabetes in all three of them, the diagnosis of MODY was considered and confirmed by molecular testing. The patient in Case 1 (a 10-year-old girl) had a variation in the HNF1A gene (MODY 3). The patient in Case 2 (a 13-year-old girl) had a variation in the HNF1B gene (MODY 5) and was also clinically diagnosed with HNF1B MODY due to short stature, abnormal renal function, renal cysts, unicornuate uterus, and diabetic ketoacidosis at presentation. The patient in Case 3 (a 14-year-old boy) had a variation in the KCNJ11 gene (MODY 13) and presented with diabetic ketoacidosis; after initially being treated as having T1DM, he developed progressive weight gain, acanthosis nigricans, and decreased requirement of insulin. The patients in Cases 1 and 3 were subsequently treated with oral sulfonylureas and insulin was gradually tapered and interrupted, resulting in drastic improvement in glucose control. The patient in Case 2 remained on insulin, as this is the appropriate management for MODY 5. This case series demonstrates that atypical cases of MODY with ketoacidosis do occur, underscoring the potential for this complication within the phenotypic spectrum of MODY. In patients with atypical presentations, a thorough family history taking may reveal the diagnosis of MODY.

Clinical screening for GCK-MODY in 2,989 patients from the Brazilian Monogenic Diabetes Study Group (BRASMOD) and the Brazilian Type 1 Diabetes Study Group (BrazDiab1SG)

Objectives

To evaluate the accuracy of routinely available parameters in screening for GCK maturity-onset diabetes of the young (MODY), leveraging data from two large cohorts - one of patients with GCK-MODY and the other of patients with type 1 diabetes (T1D).

Materials and methods

The study included 2,687 patients with T1D, 202 patients with clinical features of MODY but without associated genetic variants (NoVar), and 100 patients with GCK-MODY (GCK). Area under the receiver-operating characteristic curve (ROC-AUC) analyses were used to assess the performance of each parameter - both alone and incorporated into regression models - in discriminating between groups.

Results

The best parameter discriminating between GCK-MODY and T1D was a multivariable model comprising glycated hemoglobin (HbA1c), fasting plasma glucose, age at diagnosis, hypertension, microvascular complications, previous diabetic ketoacidosis, and family history of diabetes. This model had a ROC-AUC value of 0.980 (95% confidence interval [CI] 0.974-0.985) and positive (PPV) and negative (NPV) predictive values of 43.74% and 100%, respectively. The best model discriminating between GCK and NoVar included HbA1c, age at diagnosis, hypertension, and triglycerides and had a ROC-AUC value of 0.850 (95% CI 0.783-0.916), PPV of 88.36%, and NPV of 97.7%; however, this model was not significantly different from the others. A novel GCK variant was also described in one individual with MODY (7-44192948-T-C, p.Ser54Gly), which showed evidence of pathogenicity on in silico prediction tools.

Conclusions

This study identified a highly accurate (98%) composite model for differentiating GCK-MODY and T1D. This model may help clinicians select patients for genetic evaluation of monogenic diabetes, enabling them to implement correct treatment without overusing limited resources.

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.

Monogenic diabetes in children: An underdiagnosed and poorly managed clinical dilemma

Monogenic diabetes, constituting 1%-2% of global diabetes cases, arises from single gene defects with distinctive inheritance patterns. Despite over 50 ass-ociated genetic disorders, accurate diagnoses and management of monogenic diabetes remain inadequate, underscoring insufficient clinician awareness. The disease spectrum encompasses maturity-onset diabetes of the young (MODY), characterized by distinct genetic mutations affecting insulin secretion, and neonatal diabetes mellitus (NDM) - a heterogeneous group of severe hyperglycemic disorders in infants. Mitochondrial diabetes, autoimmune monogenic diabetes, genetic insulin resistance and lipodystrophy syndromes further diversify the monogenic diabetes landscape. A tailored approach based on phenotypic and biochemical factors to identify candidates for genetic screening is recommended for suspected cases of MODY. NDM diagnosis warrants immediate molecular genetic testing for infants under six months. Identifying these genetic defects presents a unique opportunity for precision medicine. Ongoing research aimed to develop cost-effective genetic testing methods and gene-based therapy can facilitate appropriate identification and optimize clinical outcomes. Identification and study of new genes offer a valuable opportunity to gain deeper insights into pancreatic cell biology and the pathogenic mechanisms underlying common forms of diabetes. The clinical review published in the recent issue of World Journal of Diabetes is such an attempt to fill-in our knowledge gap about this enigmatic disease.

Management of pregnancy in women with monogenic diabetes due to mutations in GCK, HNF1A and HNF4A genes

Women with maturity-onset diabetes of the young (MODY) need tailored antenatal care and monitoring of their offspring. Each MODY subtype has different implications for glycaemic targets, treatment choices and neonatal management. Hyperglycaemia of MODY is often first diagnosed in adolescence or early adulthood and therefore is clinically relevant to pregnant women. MODY remains an under-recognised and undiagnosed condition. Pregnancy represents an opportune time to make a genetic diagnosis of MODY and provide precision treatment. This review describes the nuance of antenatal care in women with MODY and the implications for pregnancies affected by a positive paternal genotype. Mutations in hepatic nuclear factor 1-alpha (HNF1A) and 4-alpha (HNF4A) genes are associated with progressive β-cell dysfunction resulting in early onset diabetes. Patients are largely managed with sulphonylureas outside of pregnancy. Macrosomia and persistent neonatal hypoglycaemia are reported in 54% and 15% of HNF4A genotype positive offspring respectively with a median increase in birthweight of 790 g. Close observation of foetal growth in utero allows optimal timing of delivery to minimise peri- and postpartum materno-foetal complications. Glucokinase (GCK)-MODY causes mild fasting hyperglycaemia which does not require treatment outside of pregnancy. Birthweight of offspring of maternal carriers is dependent on foetal genotype; heterozygous mutation carriers are usually normal weight while genotype negative offspring are large for gestational age (600 g heavier). Affected offspring of paternal carriers may be small for gestational age (500 g lighter). Serial growth scans with measurement of the abdominal circumference indirectly differentiate foetal genotype. Measurement of cell free foetal DNA in maternal blood from the late first trimester is superior to traditionally used ultrasound to distinguish foetal genotype. Cost and accessibility may limit its use.

The MODY-associated KCNK16 L114P mutation increases islet glucagon secretion and limits insulin secretion resulting in transient neonatal diabetes and glucose dyshomeostasis in adults

The gain-of-function mutation in the TALK-1 K+ channel (p.L114P) is associated with maturity-onset diabetes of the young (MODY). TALK-1 is a key regulator of β-cell electrical activity and glucose-stimulated insulin secretion. The KCNK16 gene encoding TALK-1 is the most abundant and β-cell-restricted K+ channel transcript. To investigate the impact of KCNK16 L114P on glucose homeostasis and confirm its association with MODY, a mouse model containing the Kcnk16 L114P mutation was generated. Heterozygous and homozygous Kcnk16 L114P mice exhibit increased neonatal lethality in the C57BL/6J and the CD-1 (ICR) genetic background, respectively. Lethality is likely a result of severe hyperglycemia observed in the homozygous Kcnk16 L114P neonates due to lack of glucose-stimulated insulin secretion and can be reduced with insulin treatment. Kcnk16 L114P increased whole-cell β-cell K+ currents resulting in blunted glucose-stimulated Ca2+ entry and loss of glucose-induced Ca2+ oscillations. Thus, adult Kcnk16 L114P mice have reduced glucose-stimulated insulin secretion and plasma insulin levels, which significantly impairs glucose homeostasis. Taken together, this study shows that the MODY-associated Kcnk16 L114P mutation disrupts glucose homeostasis in adult mice resembling a MODY phenotype and causes neonatal lethality by inhibiting islet insulin secretion during development. These data suggest that TALK-1 is an islet-restricted target for the treatment for diabetes.

Bioinformatics pipeline for the systematic mining genomic and proteomic variation linked to rare diseases: The example of monogenic diabetes

Monogenic diabetes is characterized as a group of diseases caused by rare variants in single genes. Like for other rare diseases, multiple genes have been linked to monogenic diabetes with different measures of pathogenicity, but the information on the genes and variants is not unified among different resources, making it challenging to process them informatically. We have developed an automated pipeline for collecting and harmonizing data on genetic variants linked to monogenic diabetes. Furthermore, we have translated variant genetic sequences into protein sequences accounting for all protein isoforms and their variants. This allows researchers to consolidate information on variant genes and proteins linked to monogenic diabetes and facilitates their study using proteomics or structural biology. Our open and flexible implementation using Jupyter notebooks enables tailoring and modifying the pipeline and its application to other rare diseases.

Clinical characteristics in children with maturity-onset diabetes of the young detected by urine glucose screening at schools in the Tokyo Metropolitan Area

This study aimed to examine the clinical characteristics of young children diagnosed with maturity-onset diabetes (MODY) using urine glucose screening at schools. The study participants were 70 non-obese children who were clinically diagnosed with type 2 diabetes through urine glucose screening at schools in Tokyo between 1974 and 2020. Of these children, 55 underwent genetic testing, and 21 were finally diagnosed with MODY: MODY2 in eight, MODY3 in eight, MODY1 in four and MODY5 in one. A family history of diabetes was found in 76.2% of the patients. Fasting plasma glucose levels did not differ between the different MODY subtypes, while patients with MODY 3, 1, and 5 had significantly higher levels of glycosylated hemoglobin and 2-hour glucose in an oral glucose tolerance test than those with MODY2. In contrast, most patients exhibit mild insulin resistance and sustained β-cell function. In the initial treatment, all patients with MODY2 were well controlled with diet and exercise, whereas the majority of those with MODY3, 1, and 5 required pharmacological treatment within one month of diagnosis. In conclusion, urine glucose screening in schools appears to be one of the best opportunities for early detection of the disease and providing appropriate treatment to patients.

MODY Probability Calculator Is Suitable for MODY Screening in China: A Population-based Study

Context

Selecting appropriate individuals for genetic testing is essential due to the optimal treatment for maturity-onset diabetes of the young (MODY). However, how to effectively screen for MODY in China remains unclear.

Objective

To validate the performance of current screening strategies in selecting patients with MODY based on a nationwide type 2 diabetes cohort.

Methods

A panel of 14 MODY genes was analyzed from 1911 type 2 diabetes patients who were ages 15 to 35 years. Variants were evaluated according to the American College of Medical Genetics and Genomics guidelines. Based on this cohort, we simulated the 2 most frequently used screening strategies, including the traditional MODY criteria and the MODY probability calculator (MPC), to assess their ability to select patients with MODY.

Results

From a total of 1911 participants, 42 participants harbored pathogenic/likely pathogenic variants. The performance of the traditional criteria was sensitivity: 19.0%, specificity: 72.9%, positive predictive value (PPV): 1.6%, and missing rate: 81.0%. The optimal cut-off for MPC was 40.7%. Based on this cut-off value, the performance was sensitivity: 54.8%, specificity: 81.0%, PPV: 6.1%, and missing rate: 45.2%. Moreover, hemoglobin A1c, insulin treatment, and family history of diabetes have poor discrimination between MODY and young-onset type 2 diabetes.

Conclusion

The MPC is better than traditional criteria in terms of both sensitivity and PPV. To ensure more MODY patients benefit from optimal treatment, we therefore suggest that routine genetic testing be performed on all type 2 diabetes patients who are between the ages of 15 and35 years and have MPC probability value over 40.7%.

Semaglutide as a potential therapeutic alternative for HNF1B-MODY: a case study

Maturity-onset diabetes of the young (MODY) is a grouping of monogenic disorders. It is characterized by dominantly inherited, non-insulin-dependent diabetes. MODY is relatively rare, encompassing up to 3.5% in those diagnosed under 30 years of age. Specific types are most commonly treated with sulfonylurea, particularly those identified as HNF4A-MODY and HNF1A-MODY. HNF1B-MODY is another type that is most frequently managed with insulin therapy but lacks a defined precision treatment. We present an 18-year-old, non-obese female patient diagnosed with HNF1B-MODY. She displays complete gene deletion, a renal cyst, and hypomagnesemia. Her treatment plan includes both long- and short-acting insulin, though she frequently encountered hypoglycemia and hyperglycemia. Semaglutide, a GLP-1RA, was administered weekly over 4 months. The patient's glucose level was continuously tracked using Dexcom's Continuous Glucose Monitoring system. The data suggested a notable improvement in her condition: time-in-range (TIR) increased from 70% to 88%, with some days achieving 100%, and the frequency of hypoglycemic episodes, indicated by time-below-range values, fell from 5% to 1%. The time-above-range values also dropped from 25% to 10%, and her HbA1c levels declined from 7% to 5.6%. During the semaglutide therapy, we were able to discontinue her insulin treatment. Additionally, her body mass index (BMI) was reduced from 24.1 to 20.1 kg/m2. However, the semaglutide treatment was halted after 4 months due to side effects such as nausea, vomiting, and reduced appetite. Other contributing factors included exam stress and a COVID-19 infection, which forced a switch back to insulin. Her last recorded HbA1c level under exclusive insulin therapy rose to 7.1%, and her BMI increased to 24.9 kg/m2. In conclusion, semaglutide could potentially replace insulin to improve glucose variability, TIR, and HbA1c in patients with HNF1B-MODY. However, more extensive studies are required to confirm its long-term safety and efficacy.

Monogenic Diabetes with GATA6 Mutations: Characterization of a Novel Family and a Comprehensive Analysis of the GATA6 Clinical and Genetics Traits

Monogenic diabetes caused by GATA6 mutations were almost described as neonatal diabetes, and the phenotypic spectrum has expanded since then. Our study underscores the broad phenotypic spectrum by reporting a de novo GATA6 mutation in a family. Furthermore, we reviewed related literature to summarize the clinical and genetic characteristics of monogenic diabetes with GATA6 mutations (n = 39) in order to improve clinicians' understanding of the disease. We conclude that the GATA6 missense mutation (c. 749G > T, p. Gly250Val) is not reported presently, characterized by adult-onset diabetes with pancreatic dysplasia and located in transcriptional activation region. Carries with GATA6 mutations (n = 55) have a variable spectrum of diabetes, ranging from neonatal (72.7%), childhood-onset (20%) to adults-onset (7.5%). 83.5% of patients with abnormal pancreatic development. Heart and hepatobillary defects are the most common abnormalities of extrapancreatic features. Most mutations with GATA6 are loss of function (LOF, 71.8%) and located in functional region. Functional studies mostly support loss-of-function as the pathophysiological mechanism. In conclusion, there are various types of diabetes with GATA6 mutations, which can also occur in adult diabetes. Phenotypic defects with GATA6 mutations are most frequently malformations of pancreas and heart. This highlights the importance of comprehensive clinical evaluation of identified carriers to evaluate their full phenotypic spectrum.

Implementing genetic testing in diabetes: Knowledge, perceptions of healthcare professionals, and barriers in a developing country

INTRODUCTION

Maturity-Onset Diabetes of the Young (MODY) is an unusual type of diabetes often missed in clinical practice, especially in Africa. Treatment decisions for MODY depend on a precise diagnosis, only made by genetic testing. We aimed to determine MODY knowledge among Nigerian healthcare professionals (HCPs), their perceptions, and barriers to the implementation of genetic testing in diabetes patients.

METHODS

A cross-sectional survey was conducted among doctors and nurses in three levels of public and private healthcare institutions in Ibadan, Nigeria, from December 2018 to June 2019. In all, 70% and 30% of a total 415 participants were recruited from public and private centers, respectively. HCPs were recruited in a 60:40% ratio, respectively. A 51-item instrument was used to assess MODY knowledge, perceptions of HCPs, and barriers to the implementation of genetic testing in diabetes patients.

RESULTS

In the survey, 43.4% self-rated their current MODY knowledge to be at least moderate. About 68%, 73% and 86%, respectively, correctly answered 3 of 5 questions on basic genetics' knowledge. However, only 1 of 7 MODY-specific questions was answered correctly by 72.7% of the respondents. The mean basic genetics and MODY-specific knowledge scores were 2.6/5 (SD=1.0) and 1.8/9 (SD=1.3), respectively. Multiple linear regression showed higher mean scores among those aged 30-49 years, those with degrees and fellowships (except PhD), and general practitioners; 360 (80.0%) perceived that genetic testing plays a central role in diabetes care. Barriers to genetic testing were lack of access to testing facilities, guidance on the use of and updates/educational materials on genetic testing (82.7%, 62.1% and 50.3%, respectively).

CONCLUSIONS

The level of MODY awareness and knowledge among Nigerian HCPs is unacceptably low with a lack of access to genetic testing facilities. These can hinder the implementation of precision diabetes medicine. Increased awareness, provision of decision support aids, and genetic testing facilities are urgently needed.

The MODY-associated KCNK16 L114P mutation increases islet glucagon secretion and limits insulin secretion resulting in transient neonatal diabetes and glucose dyshomeostasis in adults

The gain-of-function mutation in the TALK-1 K + channel (p.L114P) is associated with maturity-onset diabetes of the young (MODY). TALK-1 is a key regulator of β-cell electrical activity and glucose-stimulated insulin secretion (GSIS). The KCNK16 gene encoding TALK-1, is the most abundant and β-cell-restricted K + channel transcript. To investigate the impact of KCNK16 L114P on glucose homeostasis and confirm its association with MODY, a mouse model containing the Kcnk16 L114P mutation was generated. Heterozygous and homozygous Kcnk16 L114P mice exhibit increased neonatal lethality in the C57BL/6J and the mixed C57BL/6J:CD-1(ICR) genetic background, respectively. Lethality is likely a result of severe hyperglycemia observed in the homozygous Kcnk16 L114P neonates due to lack of glucose-stimulated insulin secretion and can be reduced with insulin treatment. Kcnk16 L114P increased whole-cell β-cell K + currents resulting in blunted glucose-stimulated Ca 2+ entry and loss of glucose-induced Ca 2+ oscillations. Thus, adult Kcnk16 L114P mice have reduced glucose-stimulated insulin secretion and plasma insulin levels, which significantly impaired glucose homeostasis. Taken together, this study shows that the MODY-associated Kcnk16 L114P mutation disrupts glucose homeostasis in adult mice resembling a MODY phenotype and causes neonatal lethality by inhibiting islet hormone secretion during development. These data strongly suggest that TALK-1 is an islet-restricted target for the treatment of diabetes.

Identification of monogenic diabetes in an Australian cohort using the Exeter maturity-onset diabetes of the young (MODY) probability calculator and next-generation sequencing gene panel testing

AIMS

This study aims to describe the prevalence of monogenic diabetes in an Australian referral cohort, in relation to Exeter maturity-onset diabetes of the young (MODY) probability calculator (EMPC) scores and next-generation sequencing with updated testing where relevant.

METHODS

State-wide 5-year retrospective cohort study of individuals referred for monogenic diabetes genetic testing.

RESULTS

After excluding individuals who had cascade testing for a familial variant (21) or declined research involvement (1), the final cohort comprised 40 probands. Incorporating updated testing, the final genetic result was positive (likely pathogenic/pathogenic variant) in 11/40 (27.5%), uncertain (variant of uncertain significance) in 8/40 (20%) and negative in 21/40 (52.5%) participants. Causative variants were found in GCK, HNF1A, MT-TL1 and HNF4A. Variants of uncertain significance included a novel multi-exonic GCK duplication. Amongst participants with EMPC scores ≥ 25%, a causative variant was identified in 37%. Cascade testing was positive in 9/10 tested relatives with diabetes and 0/6 tested relatives with no history of diabetes.

CONCLUSIONS

Contemporary genetic testing produces a high yield of positive results in individuals with clinically suspected monogenic diabetes and their relatives with diabetes, highlighting the value of genetic testing for this condition. An EMPC score cutoff of ≥ 25% correctly yielded a positive predictive value of ≥ 25% in this multiethnic demographic. This is the first Australian study to describe EMPC scores in the Australian clinic setting, albeit a biased referral cohort. Larger studies may help characterise EMPC performance between ethnic subsets, noting differences in the expected probability of monogenic diabetes relative to type 2 diabetes.

Management of monogenic diabetes in pregnancy: A narrative review

Pregnancy in women with monogenic diabetes is potentially complex, with significant implications for both maternal and fetal health. Among these, maturity-onset diabetes of the young (MODY) stands out as a prevalent monogenic diabetes subtype frequently encountered in clinical practice. Each subtype of MODY requires a distinct approach tailored to the pregnancy, diverging from management strategies in non-pregnant individuals. Glucokinase MODY (GCK-MODY) typically does not require treatment outside of pregnancy, but special considerations arise when a woman with GCK-MODY becomes pregnant. The glycemic targets in GCK-MODY pregnancies are not exclusively dictated by the maternal/paternal MODY genotype but are also influenced by the genotype of the developing fetus. During pregnancy, the choice between sulfonylurea or insulin for treating hepatocyte nuclear factor 1-alpha (HNF1A)-MODY and HNF4A-MODY depends on the mother's specific circumstances and the available expertise. Management of other rarer MODY subtypes is individualized, with decisions made on a case-by-case basis. Therefore, a collaborative approach involving expert diabetes and obstetric teams is crucial for the comprehensive management of MODY pregnancies.

2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes-2024

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, an interprofessional expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Two novel GCK mutations in Chinese patients with maturity-onset diabetes of the young

PURPOSE

Heterozygous inactivating mutations in the glucokinase (GCK) gene result in the asymptomatic fasting hyperglycemia named as GCK-MODY or MODY2. The genetic testing can effectively avoid the misdiagnosis and inappropriate treatment for GCK-MODY.

METHODS

A total of 25 unrelated families with MODY were screened for mutations in coding region of GCK by using direct sequencing. Three different bioinformatics tools such as PolyPhen2, Mutation Taster and PROVEAN were performed to predict the function of mutant proteins. The glucose profile was recorded by continuous glucose monitoring system (CGMS) to evaluate the glycemic variability for the GCK-MODY patient.

RESULTS

Our study identified five GCK mutations in 24% of the families (6/25): two novel mutations (I126fs and G385A) and three already described mutations (G44S, H50fs and S383L). In silico analyses predicted that these mutations altered structural conformational changes. The values of mean amplitude of glycemic excursions (MAGE), an important index of blood glucose fluctuation in CGMS system, were 0.81 in the first 24 h and 1.61 in the second 24 h record in the patient with GCK-MODY (F3), suggesting little glucose fluctuation.

CONCLUSION

The genetic testing is suggested to be important to differentiate GCK-MODY from other types of diabetes. CGMS might be used to screen GCK-MODY cases prior to genetic testing.

Genetic perspectives on childhood monogenic diabetes: Diagnosis, management, and future directions

Monogenic diabetes is caused by one or even more genetic variations, which may be uncommon yet have a significant influence and cause diabetes at an early age. Monogenic diabetes affects 1 to 5% of children, and early detection and gene-tically focused treatment of neonatal diabetes and maturity-onset diabetes of the young can significantly improve long-term health and well-being. The etiology of monogenic diabetes in childhood is primarily attributed to genetic variations affecting the regulatory genes responsible for beta-cell activity. In rare instances, mutations leading to severe insulin resistance can also result in the development of diabetes. Individuals diagnosed with specific types of monogenic diabetes, which are commonly found, can transition from insulin therapy to sulfonylureas, provided they maintain consistent regulation of their blood glucose levels. Scientists have successfully devised materials and methodologies to distinguish individuals with type 1 or 2 diabetes from those more prone to monogenic diabetes. Genetic screening with appropriate findings and interpretations is essential to establish a prognosis and to guide the choice of therapies and management of these interrelated ailments. This review aims to design a comprehensive literature summarizing genetic insights into monogenetic diabetes in children and adolescents as well as summarizing their diagnosis and mana-gement.

Early-onset diabetes in Africa: A mini-review of the current genetic profile

Early-onset diabetes is poorly diagnosed partly due to its heterogeneity and variable presentations. Although several genes have been associated with the disease, these genes are not well studied in Africa. We sought to identify the major neonatal, early childhood, juvenile, or early-onset diabetes genes in Africa; and evaluate the available molecular methods used for investigating these gene variants. A literature search was conducted on PubMed, Scopus, Africa-Wide Information, and Web of Science databases. The retrieved records were screened and analyzed to identify genetic variants associated with early-onset diabetes. Although 319 records were retrieved, 32 were considered for the current review. Most of these records (22/32) were from North Africa. The disease condition was genetically heterogenous with most cases possessing unique gene variants. We identified 22 genes associated with early-onset diabetes, 9 of which had variants (n = 19) classified as pathogenic or likely pathogenic (PLP). Among the PLP variants, IER3IP1: p.(Leu78Pro) was the variant with the highest number of cases. There was limited data from West Africa, hence the contribution of genetic variability to early-onset diabetes in Africa could not be comprehensively evaluated. It is worth mentioning that most studies were focused on natural products as antidiabetics and only a few studies reported on the genetics of the disease. ABCC8 and KCNJ11 were implicated as major contributors to early-onset diabetes gene networks. Gene ontology analysis of the network associated ion channels, impaired glucose tolerance, and decreased insulin secretions to the disease. Our review highlights 9 genes from which PLP variants have been identified and can be considered for the development of an African diagnostic panel. There is a gap in early-onset diabetes genetic research from sub-Saharan Africa which is much needed to develop a comprehensive, efficient, and cost-effective genetic panel that will be useful in clinical practice on the continent and among the African diasporas.

Unknown presentation of a rare genetic disorder: Monogenic diabetes in young type 4 presenting with hepatic cysts and procoagulant state

Maturity onset diabetes in young (MODY) is the most common form of monogenic diabetes, which characteristically presents in adolescents and young adults. Till date, pathogenic variations involving 14 different genes have been causally implicated with the development of MODY. Maturity onset diabetes in young type 4 (MODY-4) is a very rare form of MODY. We present here case of 28-year-old nonobese male patient with distinct family history of diabetes spanning two generations, incidentally, detected to have a rare form of diabetes on genetic analysis when he presented with recurrent thromboembolic manifestations: deep vein thrombosis and pulmonary thromboembolism. Our case highlights a previously unknown disease association of a rare genetic disorder. Increasing awareness about this genetic disorder and early identification of such cases will enhance our understanding of hitherto unknown disease associations and the pathophysiological role of genetic mutations. This may contribute to the improved treatment and prevention of debilitating diseases such as diabetes.

Characterisation of HNF1A variants in paediatric diabetes in Norway using functional and clinical investigations to unmask phenotype and monogenic diabetes

AIMS/HYPOTHESIS

Correctly diagnosing MODY is important, as individuals with this diagnosis can discontinue insulin injections; however, many people are misdiagnosed. We aimed to develop a robust approach for determining the pathogenicity of variants of uncertain significance in hepatocyte nuclear factor-1 alpha (HNF1A)-MODY and to obtain an accurate estimate of the prevalence of HNF1A-MODY in paediatric cases of diabetes.

METHODS

We extended our previous screening of the Norwegian Childhood Diabetes Registry by 830 additional samples and comprehensively genotyped HNF1A variants in autoantibody-negative participants using next-generation sequencing. Carriers of pathogenic variants were treated by local healthcare providers, and participants with novel likely pathogenic variants and variants of uncertain significance were enrolled in an investigator-initiated, non-randomised, open-label pilot study (ClinicalTrials.gov registration no. NCT04239586). To identify variants associated with HNF1A-MODY, we functionally characterised their pathogenicity and assessed the carriers' phenotype and treatment response to sulfonylurea.

RESULTS

In total, 615 autoantibody-negative participants among 4712 cases of paediatric diabetes underwent genetic sequencing, revealing 19 with HNF1A variants. We identified nine carriers with novel variants classified as variants of uncertain significance or likely to be pathogenic, while the remaining ten participants carried five pathogenic variants previously reported. Of the nine carriers with novel variants, six responded favourably to sulfonylurea. Functional investigations revealed their variants to be dysfunctional and demonstrated a correlation with the resulting phenotype, providing evidence for reclassifying these variants as pathogenic.

CONCLUSIONS/INTERPRETATION

Based on this robust classification, we estimate that the prevalence of HNF1A-MODY is 0.3% in paediatric diabetes. Clinical phenotyping is challenging and functional investigations provide a strong complementary line of evidence. We demonstrate here that combining clinical phenotyping with functional protein studies provides a powerful tool to obtain a precise diagnosis of HNF1A-MODY.

Prevalence and Clinical Characteristics of PDX1 Variant Induced Diabetes in Chinese Early-Onset Type 2 Diabetes

CONTEXT

Maturity-onset diabetes of the young 4 (MODY4) is caused by mutations of PDX1; its prevalence and clinical features are not well known.

OBJECTIVE

This study aimed to investigate the prevalence and clinical characteristics of MODY4 in Chinese people clinically diagnosed with early-onset type 2 diabetes (EOD), and to evaluate the relationship between the PDX1 genotype and the clinical phenotype.

METHOD

The study cohort consisted of 679 patients with EOD. PDX1 mutations were screened by DNA sequencing, and their pathogenicity was evaluated by functional experiments and American College of Medical Genetics and Genomics guidelines. MODY4 was diagnosed in individuals with diabetes who carry a pathogenic or likely pathogenic PDX1 variant. All reported cases were reviewed for analyzing the genotype-phenotype relationship.

RESULT

4 patients with MODY4 were identified, representing 0.59% of this Chinese EOD cohort. All the patients were diagnosed before 35 years old, either obese or not obese. Combined with previously reported cases, the analysis revealed that the carriers of homeodomain variants were diagnosed earlier than those with transactivation domain variants (26.10 ± 11.00 vs 41.85 ± 14.66 years old, P < .001), and the proportions of overweight and obese individuals with missense mutation were higher than those with nonsense or frameshift mutations (27/34 [79.4%] vs 3/8 [37.5%], P = .031).

CONCLUSION

Our study suggested that MODY4 was prevalent in 0.59% of patients with EOD in a Chinese population. It was more difficult to identify clinically than other MODY subtypes owning to its clinical similarity to EOD. Also, this study revealed that there is some relationship between genotype and phenotype.

The case for precision medicine in the prevention, diagnosis, and treatment of cardiometabolic diseases in low-income and middle-income countries

Cardiometabolic diseases are the leading preventable causes of death in most geographies. The causes, clinical presentations, and pathogenesis of cardiometabolic diseases vary greatly worldwide, as do the resources and strategies needed to prevent and treat them. Therefore, there is no single solution and health care should be optimised, if not to the individual (ie, personalised health care), then at least to population subgroups (ie, precision medicine). This optimisation should involve tailoring health care to individual disease characteristics according to ethnicity, biology, behaviour, environment, and subjective person-level characteristics. The capacity and availability of local resources and infrastructures should also be considered. Evidence needed for equitable precision medicine cannot be generated without adequate data from all target populations, and the idea that research done in high-income countries will transfer adequately to low-income and middle-income countries (LMICs) is problematic, as many migration studies and transethnic comparisons have shown. However, most data for precision medicine research are derived from people of European ancestry living in high-income countries. In this Series paper, we discuss the case for precision medicine for cardiometabolic diseases in LMICs, the barriers and enablers, and key considerations for implementation. We focus on three propositions: first, failure to explore and implement precision medicine for cardiometabolic disease in LMICs will enhance global health disparities. Second, some LMICs might already be placed to implement cardiometabolic precision medicine under appropriate circumstances, owing to progress made in treating infectious diseases. Third, improvements in population health from precision medicine are most probably asymptotic; the greatest gains are more likely to be obtained in countries where health-care systems are less developed. We outline key recommendations for implementation of precision medicine approaches in LMICs.

Glucokinase Variant Proteins Are Resistant to Fasting-Induced Uridine Diphosphate Glucose-Dependent Degradation in Maturity-Onset Diabetes of the Young Type 2 Patients

We previously reported that glucokinase undergoes ubiquitination and subsequent degradation, a process mediated by cereblon, particularly in the presence of uridine diphosphate glucose (UDP-glucose). In this context, we hereby present evidence showcasing the resilience of variant glucokinase proteins of maturity-onset diabetes of the young type 2 (MODY2) against degradation and, concomitantly, their influence on insulin secretion, both in cell lines and in the afflicted MODY2 patient. Hence, glucose-1-phodphate promotes UDP-glucose production by UDP-glucose pyrophosphorylase 2; consequently, UDP-glucose-dependent glucokinase degradation may occur during fasting. Next, we analyzed glucokinase variant proteins from MODY2 or persistent hyperinsulinemic hypoglycemia in infancy (PHHI). Among the eleven MODY2 glucokinase-mutated proteins tested, those with a lower glucose-binding affinity exhibited resistance to UDP-glucose-dependent degradation. Conversely, the glucokinaseA456V-mutated protein from PHHI had a higher glucose affinity and was sensitive to UDP-glucose-dependent degradation. Furthermore, in vitro studies involving UDP-glucose-dependent glucokinase variant proteins and insulin secretion during fasting in Japanese MODY2 patients revealed a strong correlation and a higher coefficient of determination. This suggests that UDP-glucose-dependent glucokinase degradation plays a significant role in the pathogenesis of glucose-homeostasis-related hereditary diseases, such as MODY2 and PHHI.

Cardio-cerebrovascular Outcomes in MODY, Type 1 Diabetes, and Type 2 Diabetes: A Prospective Cohort Study

CONTEXT

Cardio-cerebrovascular events are severe complications of diabetes.

OBJECTIVE

We aim to compare the incident risk of cardio-cerebrovascular events in maturity onset diabetes of the young (MODY), type 1 diabetes, and type 2 diabetes.

METHODS

Type 1 diabetes, type 2 diabetes, and MODY were diagnosed by whole exome sequencing. The primary endpoint was the occurrence of the first major adverse cardiovascular event (MACE), including acute myocardial infarction, heart failure, stroke, unstable angina pectoris, and cardio-cerebrovascular-related mortality. Cox proportional hazards models were applied and adjusted to calculate hazard ratios (HRs) and 95% CIs for the incident risk of MACE in type 1 diabetes, type 2 diabetes, MODY, and MODY subgroups compared with people without diabetes (control group).

RESULTS

Type 1 diabetes, type 2 diabetes, and MODY accounted for 2.7%, 68.1%, and 11.4% of 26 198 participants with diabetes from UK Biobank. During a median follow-up of 13 years, 1028 MACEs occurred in the control group, contrasting with 70 events in patients with type 1 diabetes (HR 2.15, 95% CI 1.69-2.74, P < .05), 5020 events in patients with type 2 diabetes (HR 7.02, 95% CI 6.56-7.51, P < .05), and 717 events in MODY (HR 5.79, 95% CI 5.26-6.37, P < .05). The hazard of MACE in HNF1B-MODY was highest among MODY subgroups (HR 11.00, 95% CI 5.47-22.00, P = 1.5 × 10-11).

CONCLUSION

MODY diagnosed by genetic analysis represents higher prevalence than the clinical diagnosis in UK Biobank. The risk of incident cardio-cerebrovascular events in MODY ranks between type 1 diabetes and type 2 diabetes.

Maturity-onset diabetes of the young type 9 or latent autoimmune diabetes in adults: A case report and review of literature

BACKGROUND

Maturity-onset diabetes of the young (MODY) is a monogenic genetic disease often clinically misdiagnosed as type 1 or type 2 diabetes. MODY type 9 (MODY9) is a rare subtype caused by mutations in the PAX4 gene. Currently, there are limited reports on PAX4-MODY, and its clinical characteristics and treatments are still unclear. In this report, we described a Chinese patient with high autoimmune antibodies, hyperglycemia and a site mutation in the PAX4 gene.

CASE SUMMARY

A 42-year-old obese woman suffered diabetes ketoacidosis after consuming substantial amounts of beverages. She had never had diabetes before, and no one in her family had it. However, her autoantibody tested positive, and she managed her blood glucose within the normal range for 6 mo through lifestyle inter-ventions. Later, her blood glucose gradually increased. Next-generation sequencing and Sanger sequencing were performed on her family. The results revealed that she and her mother had a heterozygous mutation in the PAX4 gene (c.314G>A, p.R105H), but her daughter did not. The patient is currently taking liraglutide (1.8 mg/d), and her blood glucose levels are under control. Previous cases were retrieved from PubMed to investigate the relationship between PAX4 gene mutations and diabetes.

CONCLUSION

We reported the first case of a PAX4 gene heterozygous mutation site (c.314G>A, p.R105H), which does not appear pathogenic to MODY9 but may facilitate the progression of latent autoimmune diabetes in adults.

Identification of appropriate biochemical parameters and cut points to detect Maturity Onset Diabetes of Young (MODY) in Asian Indians in a clinic setting

Maturity Onset Diabetes of the Young (MODY) is a monogenic form of diabetes which is detected by genetic testing. We looked at clinical and biochemcial variables that could help detect possible MODY among Asian Indians with youth-onset diabetes. From the diabetes electronic medical records of a diabetes care centre in Chennai in southern India, demographic, anthropometric, and biochemical details of 34 genetically confirmed MODY participants were extracted. They were compared with patients with type 1 diabetes (T1D) (n = 1011) and type 2 diabetes (T2D) (n = 1605), diagnosed below 30 years of age. Clinical and biochemical variables including body mass index (BMI), glycated hemoglobin, HDL cholesterol, and C-peptide (fasting and stimulated) were analyzed to determine whether cut points could be derived to identify individuals who could be sent for genetic testing to diagnose or rule out MODY in this ethnic group. The age at diagnosis was higher for T2D (26.5 ± 4.0 years) compared to T1D (18.2 ± 6.1 years) and MODY (17.8 ± 6.0 years). Individuals with MODY had BMI, glycated hemoglobin, total cholesterol, triglycerides, HDL cholesterol, and C-peptide levels which were intermediate between T1D and T2D. The identified probable parameters and their cut points to identify cases for MODY genetic screening were BMI 21.2-22.7 kg/m2, glycated hemoglobin 7.2-10%, HDL cholesterol 43-45 mg/dl, fasting C -peptide, 1.2-2.1 ng/ml and stimulated C-peptide, 2.1-4.5 ng/ml. Asian Indians with MODY have clinical features that are intermediate between T1D and T2D and selected biochemical parameters, especially stimulated C peptide cut points were the most useful to diagnose MODY.

Human gain-of-function variants in HNF1A confer protection from diabetes but independently increase hepatic secretion of atherogenic lipoproteins

Loss-of-function mutations in hepatocyte nuclear factor 1A (HNF1A) are known to cause rare forms of diabetes and alter hepatic physiology through unclear mechanisms. In the general population, 1:100 individuals carry a rare, protein-coding HNF1A variant, most of unknown functional consequence. To characterize the full allelic series, we performed deep mutational scanning of 11,970 protein-coding HNF1A variants in human hepatocytes and clinical correlation with 553,246 exome-sequenced individuals. Surprisingly, we found that ∼1:5 rare protein-coding HNF1A variants in the general population cause molecular gain of function (GOF), increasing the transcriptional activity of HNF1A by up to 50% and conferring protection from type 2 diabetes (odds ratio [OR] = 0.77, p = 0.007). Increased hepatic expression of HNF1A promoted a pro-atherogenic serum profile mediated in part by enhanced transcription of risk genes including ANGPTL3 and PCSK9. In summary, ∼1:300 individuals carry a GOF variant in HNF1A that protects carriers from diabetes but enhances hepatic secretion of atherogenic lipoproteins.

Genetic and Clinical Characterization of Patients with HNF1B-Related MODY in Croatia

BACKGROUND

Mutation of the gene encoding Hepatocyte Nuclear transcription Factor-1 Beta (HNF1B) causes a rare monogenetic subtype of Maturity-Onset Diabetes of the Young (MODY). HNF1B-related MODY results in the dysfunction of multiple organ systems. However, genetic analysis enables personalized medicine for patients and families.

AIMS

To understand the clinical characteristics and explore the gene mutations in Croatian patients.

METHODS

This was a retrospective observational study of individuals (and their relatives) who were, due to the clinical suspicion of MODY, referred to the Department of Laboratory Diagnostics at the University Hospital Centre Zagreb for genetic testing.

RESULTS

A total of 118 participants, 56% females, were screened. Seven patients (three females) from five families were identified to have HNF1B-related MODY. The median age at diagnosis was 31 (11-45) years, the median c-peptide was 0.8 (0.55-1.39) nmol/L, the median HbA1c was 9.1 (5.7-18.4)%, and the median BMI was 22.9 kg/m² (17-24.6). Patients had a variety of clinical manifestations; kidney disease was not as frequent as liver lesions, neuropsychiatric symptoms, hyperlipidemia, hyperuricemia, and hypomagnesemia. We identified two new pathogenic mutations (c.1006C > G protein p.His336Asp on exon 4 and c.1373T > G p protein Val458Gly on exon 7).

CONCLUSIONS

In a study involving Croatian patients, new genetic (two previously unknown mutations) and clinical (diverse range of clinical presentations) aspects of HNF1B-related MODY were found.

Identification of pathogenic GCK variants in patients with common type 2 diabetes can lead to discontinuation of pharmacological treatment

Background

Functionally disruptive variants in the glucokinase gene (GCK) cause a form of mild non-progressive hyperglycemia, which does not require pharmacological treatment. A substantial proportion of patients with type 2 diabetes (T2D) carry GCK variants. We aimed to investigate whether carriers of rare GCK variants diagnosed with T2D have a glycemic phenotype and treatment response consistent with GCK-diabetes.

Methods

Eight patients diagnosed with T2D from the Danish DD2 cohort who had previously undergone sequencing of GCK participated. Clinical examinations at baseline included an oral glucose tolerance test and continuous glucose monitoring. Carriers with a glycemic phenotype consistent with GCK-diabetes took part in a three-month treatment withdrawal.

Results

Carriers of pathogenic and likely pathogenic variants had lower median fasting glucose and C-peptide levels compared to carriers of variants of uncertain significance and benign variants (median fasting glucose: 7.3 (interquartile range: 0.4) mmol/l vs. 9.5 (1.6) mmol/l, p = 0.04; median fasting C-peptide 902 (85) pmol/l vs. 1535 (295) pmol/l, p = 0.03). Four participants who discontinued metformin treatment and one diet-treated participant were reevaluated after three months. There was no deterioration of HbA1c or fasting glucose (median baseline HbA1c: 49 (3) vs. 51 (6) mmol/mol after three months, p = 0.4; median baseline fasting glucose: 7.3 (0.4) mmol/l vs. 7.0 (0.6) mmol/l after three months, p = 0.5). Participants did not consistently fulfill best practice guidelines for GCK screening nor clinical criteria for monogenic diabetes.

Discussion

Carriers of pathogenic or likely pathogenic GCK variants identified by unselected screening in T2D should be reported, as they have a glycemic phenotype and treatment response consistent with GCK-diabetes. Variants of uncertain significance should be interpreted with care. Systematic genetic screening of patients with common T2D receiving routine care can lead to the identification and precise care of patients with misclassified GCK-diabetes who are not identifiable through common genetic screening criteria.

Genetic testing for misclassified monogenic diabetes in Māori and Pacific peoples in Aōtearoa New Zealand with early-onset type 2 diabetes

Aims

Monogenic diabetes accounts for 1-2% of diabetes cases yet is often misdiagnosed as type 2 diabetes. The aim of this study was to examine in Māori and Pacific adults clinically diagnosed with type 2 diabetes within 40 years of age, (a) the prevalence of monogenic diabetes in this population (b) the prevalence of beta-cell autoantibodies and (c) the pre-test probability of monogenic diabetes.

Methods

Targeted sequencing data of 38 known monogenic diabetes genes was analyzed in 199 Māori and Pacific peoples with BMI of 37.9 ± 8.6 kg/m² who had been diagnosed with type 2 diabetes between 3 and 40 years of age. A triple-screen combined autoantibody assay was used to test for GAD, IA-2, and ZnT8. MODY probability calculator score was generated in those with sufficient clinical information (55/199).

Results

No genetic variants curated as likely pathogenic or pathogenic were found. One individual (1/199) tested positive for GAD/IA-2/ZnT8 antibodies. The pre-test probability of monogenic diabetes was calculated in 55 individuals with 17/55 (31%) scoring above the 20% threshold considered for diagnostic testing referral.

Discussion

Our findings suggest that monogenic diabetes is rare in Māori and Pacific people with clinical age, and the MODY probability calculator likely overestimates the likelihood of a monogenic cause for diabetes in this population.

A comprehensive map of human glucokinase variant activity

BACKGROUND

Glucokinase (GCK) regulates insulin secretion to maintain appropriate blood glucose levels. Sequence variants can alter GCK activity to cause hyperinsulinemic hypoglycemia or hyperglycemia associated with GCK-maturity-onset diabetes of the young (GCK-MODY), collectively affecting up to 10 million people worldwide. Patients with GCK-MODY are frequently misdiagnosed and treated unnecessarily. Genetic testing can prevent this but is hampered by the challenge of interpreting novel missense variants.

RESULT

Here, we exploit a multiplexed yeast complementation assay to measure both hyper- and hypoactive GCK variation, capturing 97% of all possible missense and nonsense variants. Activity scores correlate with in vitro catalytic efficiency, fasting glucose levels in carriers of GCK variants and with evolutionary conservation. Hypoactive variants are concentrated at buried positions, near the active site, and at a region of known importance for GCK conformational dynamics. Some hyperactive variants shift the conformational equilibrium towards the active state through a relative destabilization of the inactive conformation.

CONCLUSION

Our comprehensive assessment of GCK variant activity promises to facilitate variant interpretation and diagnosis, expand our mechanistic understanding of hyperactive variants, and inform development of therapeutics targeting GCK.

Diagnosis, treatment and disclosure: A qualitative exploration of participant challenges in a Monogenic Diabetes Registry

PURPOSE

Maturity-onset diabetes of the young (MODY) represents a heterogenous group of monogenic diabetes. Despite its autosomal dominant inheritance, many MODY participants in the University of Chicago Monogenic Diabetes Registry have no family members enrolled. We aimed to gather data on the Registry participants' experiences in (1) receipt of an accurate diagnosis, (2) decisions regarding disclosure of their MODY genetic test results with biological relatives, and (3) recommendations toward our Registry's processes and outreach.

METHODS

We conducted 20 one-on-one semistructured interviews with adult Registry participants.

RESULTS

All participants found navigating the health care system challenging because of the providers' unfamiliarity with MODY and dismissal of its importance post diagnosis. All had shared their results with at least 1 relative, however many found their relatives resistant to engaging with their providers. Participants wanted to receive targeted information on their condition and connect with other participants who have faced similar diagnostic and treatment challenges.

CONCLUSION

Our results demonstrate that our probands faced resistance to reclassification of their diabetes from both health care providers and relatives. In an effort to improve cascade testing, the Registry is designing a portal to facilitate participant-research team communication and provide additional supports for participants to involve family members in testing.

Monogenic diabetes

Monogenic diabetes includes several clinical conditions generally characterized by early-onset diabetes, such as neonatal diabetes, maturity-onset diabetes of the young (MODY) and various diabetes-associated syndromes. However, patients with apparent type 2 diabetes mellitus may actually have monogenic diabetes. Indeed, the same monogenic diabetes gene can contribute to different forms of diabetes with early or late onset, depending on the functional impact of the variant, and the same pathogenic variant can produce variable diabetes phenotypes, even in the same family. Monogenic diabetes is mostly caused by impaired function or development of pancreatic islets, with defective insulin secretion in the absence of obesity. The most prevalent form of monogenic diabetes is MODY, which may account for 0.5-5% of patients diagnosed with non-autoimmune diabetes but is probably underdiagnosed owing to insufficient genetic testing. Most patients with neonatal diabetes or MODY have autosomal dominant diabetes. More than 40 subtypes of monogenic diabetes have been identified to date, the most prevalent being deficiencies of GCK and HNF1A. Precision medicine approaches (including specific treatments for hyperglycaemia, monitoring associated extra-pancreatic phenotypes and/or following up clinical trajectories, especially during pregnancy) are available for some forms of monogenic diabetes (including GCK- and HNF1A-diabetes) and increase patients' quality of life. Next-generation sequencing has made genetic diagnosis affordable, enabling effective genomic medicine in monogenic diabetes.

Prevalence and characteristics of misdiagnosed adult-onset type 1 diabetes mellitus in Thai people by random plasma C-peptide testing

Background

It is critical to determine the exact type of diabetes because misclassification led to inappropriate treatments. The classification of DM can be aided by the measurement of pancreatic autoantibodies and plasma C-peptide levels. Previous studies suggested that random plasma C-peptide testing in those with clinically diagnosed adult T1DM of at least 3 years duration has led to reclassification in some cases.

Aim

This study aimed to assess the prevalence and characteristics of misdiagnosed adult-onset type 1 diabetes mellitus in Thai people by random plasma C-peptide testing.

Methods

A cross-sectional study of adult Thai patients diagnosed with clinically diagnosed T1DM and DM duration of at least 3 years at Theptarin Hospital, a diabetes center in Bangkok, Thailand was studied. Clinically misdiagnosis of T1DM was defined by preserved endogenous insulin secretion. Characteristics of the misdiagnosed patients were compared with definite T1DM patients.

Results

A total of 73 patients (females 52.1%, mean age 42.2 ± 12.5 years, duration of DM 20.3 ± 11.3 years) were studied. The prevalence of available anti-GAD and anti-IA2 were 53.3% and 20.8%, respectively. Preserved endogenous insulin secretion evaluated by random C-peptide or stimulated C-peptide was found in 8 patients (11.0%). The misdiagnosed patients had higher prevalence of hypertension and diabetic complications. Three patients were suspected to have monogenic diabetes and five patients were reclassified as possible T2DM.

Conclusions

Approximately one-tenth of adult T1DM patients were misdiagnosed. Random plasma C-peptide testing at least 3 years after a diagnosis of T1DM was superior to the measurement of pancreatic autoantibodies. Our present study highlights the need to increase accuracy in the diagnosis of T1DM patients by re-assessing endogenous insulin production with measurement of random plasma C-peptide levels.

Novel gene mutation in maturity-onset diabetes of the young: A case report

BACKGROUND

Maturity-onset diabetes of the young (MODY) is the most common monogenic type of diabetes. Recently, 14 gene mutations have been found to be associated with MODY. In addition, the KLF11 gene mutation is the pathogenic gene of MODY7. To date, the clinical and functional characteristics of the novel KLF11 mutation c. G31A have not yet been reported.

CASE SUMMARY

We report of a 30-year-old male patient with a one-year history of nonketosis-prone diabetes and a 3-generation family history of diabetes. The patient was found to carry a KLF11 gene mutation. Therefore, the clinical data of family members were collected and investigated. A total of four members of the family were found to have heterozygous mutations in the KLF11 gene c. G31A, which resulted in a change in the corresponding amino acid p.D11N. Three patients had diabetes mellitus, and one patient had impaired glucose tolerance.

CONCLUSION

The heterozygous mutation of the KLF11 gene c.G31A (p. D11N) is a new mutation site of MODY7. Subsequently, the main treatment included dietary interventions and oral drugs.

De novo HNF1A mutation of young maturity-onset diabetes 3 of a young girl-Case report

Young maturity-onset diabetes of the young type3(MODY3) as a special type of diabetes, the probability of diagnosis is low. This article reports on a case and reviews the relevant knowledge of the disease. We report an 11-year-and-11-month-old girl whose grandmother died from diabetic complications while the rest of the families were non-diabetes. The proband was initially treated with insulin and metformin but the threatment proved inefficient. After an exome-targeted capture sequencing test, she was diagnosed with mature-onset diabetes of young type 3 (MODY3), and sulfonylureas make sense. The key to mody treatment is a correct and timely diagnosis, which contributes to helping patients overcome the problems of MODY3, especially for blood sugar control.

The Mutation Spectrum of Rare Variants in the Gene of Adenosine Triphosphate (ATP)-Binding Cassette Subfamily C Member 8 in Patients with a MODY Phenotype in Western Siberia

During differential diagnosis of diabetes mellitus, the greatest difficulties are encountered with young patients because various types of diabetes can manifest themselves in this age group (type 1, type 2, and monogenic types of diabetes mellitus, including maturity-onset diabetes of the young (MODY)). The MODY phenotype is associated with gene mutations leading to pancreatic-β-cell dysfunction. Using next-generation sequencing technology, targeted sequencing of coding regions and adjacent splicing sites of MODY-associated genes (HNF4A, GCK, HNF1A, PDX1, HNF1B, NEUROD1, KLF11, CEL, PAX4, INS, BLK, KCNJ11, ABCC8, and APPL1) was carried out in 285 probands. Previously reported missense variants c.970G>A (p.Val324Met) and c.1562G>A (p.Arg521Gln) in the ABCC8 gene were found once each in different probands. Variant c.1562G>A (p.Arg521Gln) in ABCC8 was detected in a compound heterozygous state with a pathogenic variant of the HNF1A gene in a diabetes patient and his mother. Novel frameshift mutation c.4609_4610insC (p.His1537ProfsTer22) in this gene was found in one patient. All these variants were detected in available family members of the patients and cosegregated with diabetes mellitus. Thus, next-generation sequencing of MODY-associated genes is an important step in the diagnosis of rare MODY subtypes.

Prevalence of maturity-onset diabetes of the young in phenotypic type 2 diabetes in young adults: a nationwide, multi-center, cross-sectional survey in China

BACKGROUND

Maturity-onset diabetes of the young (MODY) is the most common monogenic diabetes. The aim of this study was to assess the prevalence of MODY in phenotypic type 2 diabetes (T2DM) among Chinese young adults.

METHODS

From April 2015 to October 2017, this cross-sectional study involved 2429 consecutive patients from 46 hospitals in China, newly diagnosed between 15 years and 45 years, with T2DM phenotype and negative for standardized glutamic acid decarboxylase antibody at the core laboratory. Sequencing using a custom monogenic diabetes gene panel was performed, and variants of 14 MODY genes were interpreted as per current guidelines.

RESULTS

The survey determined 18 patients having genetic variants causing MODY (6 HNF1A , 5 GCK , 3 HNF4A , 2 INS , 1 PDX1 , and 1 PAX4 ). The prevalence of MODY was 0.74% (95% confidence interval [CI]: 0.40-1.08%). The clinical characteristics of MODY patients were not specific, 72.2% (13/18) of them were diagnosed after 35 years, 47.1% (8/17) had metabolic syndrome, and only 38.9% (7/18) had a family history of diabetes. No significant difference in manifestations except for hemoglobin A1c levels was found between MODY and non-MODY patients.

CONCLUSION

The prevalence of MODY in young adults with phenotypic T2DM was 0.74%, among which HNF1A -, GCK -, and HNF4A -MODY were the most common subtypes. Clinical features played a limited role in the recognition of MODY.