Clinical presentation and long-term outcome of patients with KCNJ11/ABCC8 variants: Neonatal diabetes or MODY in the DPV registry from Germany and Austria

Zebrafish as a preclinical model for diabetes mellitus and its complications: From monogenic to gestational diabetes and beyond

With diabetes currently affecting 537 million people globally, innovative research approaches are urgently required. Zebrafish (Danio rerio) has emerged as a pivotal model organism in diabetes research, particularly valuable for developmental biology studies and preclinical therapeutic validation. Its rapid life cycle, optical transparency, and genetic tractability collectively enable efficient longitudinal observation of pathological progression and pharmacological responses. Utilizing zebrafish models, researchers have elucidated fundamental mechanisms governing islet development, β-cell dysfunction, and metabolic dysregulation. These experimental systems have significantly advanced our understanding of various diabetes subtypes, including type 1, type 2, gestational, and monogenic forms, while also facilitating mechanistic studies of diabetic complications such as retinopathy and nephropathy. Recent model refinements, particularly in simulating monogenic disorders and pregnancy-associated metabolic changes, promise to deepen our comprehension of disease pathophysiology and therapeutic interventions. Nevertheless, a persistent limitation lies in their incomplete recapitulation of human-specific physiological complexity and multi-organ metabolic interactions, factors that may influence translational applicability. Despite these constraints, zebrafish-based research continues to provide an indispensable platform for diabetes investigation, holding significant promise for alleviating the escalating global burden of this metabolic disorder.

Clinical and Genetic Characteristics and Outcome in Patients with Neonatal Diabetes Mellitus from a Low Middle-income Country

Neonatal diabetes mellitus (NDM) is a disorder characterized by persistent, severe hyperglycemia presenting during the first six months of life. These disorders are rare and the incidence is approximately 1 in 90,000 live births. The aim was to describe the clinical presentation, molecular genetics and outcome of patients with NDM from a single paediatric endocrine center from a low-middle income country, Sri Lanka. A retrospective study was conducted on patients diagnosed with NDM. Medical records were reviewed for demographic data and data on clinical, biochemical and genetic analysis. The majority (96%) who underwent mutation analysis had pathogenic genetic mutations on Sanger sequencing. Permanent NDM (PNDM) was diagnosed in 19 patients with three having a syndromic diagnosis. The most common mutation was in KCNJ11. The majority of patients with PNDM (63%) presented with severe diabetic ketoacidosis. All patients with Transient NDM remitted by six months of age. Nearly half (47%) with PNDM were switched to sulfonylurea therapy with good glycemic control (glycosylated haemoglobin A1c ranged 6-7.5%). Data from the Sri Lankan cohort is comparable with other populations. The majority of cases are due to KCNJ11 mutations resulting in PNDM.

Identification of heterozygous mutations of ABCC8 gene responsible for maturity-onset diabetes of the young with exome sequencing

BACKGROUND

Although the MODY12 subtype, caused by ABCC8 mutations, is rare, it is highly sensitive to sulfonylureas. The identification of ABCC8 mutations in patients clinically diagnosed with MODY has the ability to contribute to the precise management of diabetes.

METHODS

Genetic analysis of two families with MODY were conducted using whole-exome sequencing (WES) and Sanger sequencing. The spatial structures of the mutant proteins were constructed using MODELLER and PyMOL software to provide further evidence of pathogenicity.

RESULTS

The heterozygous missense mutations V357I and R1393H in ABCC8 were found in probands of two unrelated MODY pedigrees, which co-segregated with the hyperglycemic phenotypes in these two pedigrees. Detection of the V357I mutation enabled the proband of family A to successfully transfer from insulin to sulfonylurea (SU). After 3 months of follow-up for the SU trial, the HbA1c level of proband A improved from 12.4% at the initial diagnosis to 7.20%. Proband B was treated with insulin because of pregnancy and poor islet function. In silico analysis indicated that the R1393H mutation resulted in a longer hydrogen bond distance to L1389 and cleavage of carbon-hydrogen bonds to V1395, A1390, and L1389.

CONCLUSIONS

We have described two pathogenic missense mutations in ABCC8 in Chinese families with MODY. Our findings support the heterogeneity in the clinical features of MODY12 caused by ABCC8 mutations.

Clinical characteristics, treatment, and treatment switch after molecular-genetic classification in individuals with maturity-onset diabetes of the young: Insights from the multicenter real-world DPV registry

BACKGROUND

Individuals with maturity-onset diabetes of the young (MODY) are often misdiagnosed as type 1 or type 2 diabetes and receive inappropriate care. We aimed to investigate the characteristics and treatment of all MODY types in a multicenter, real-world setting.

METHODS

Individuals with MODY from the diabetes prospective follow-up (DPV) registry were studied. We compared clinical parameters during the first year of diabetes and the most recent treatment year after MODY diagnosis.

RESULTS

A total of 1640 individuals were identified with GCK-MODY (n = 941) and HNF1A-MODY (n = 417) as the most frequent types. Among these, 912 individuals were available with information during the first and the most recent treatment year (median duration of follow-up: 4.2 years [2.6-6.6]). Positive beta cell autoantibodies were present in 20.6% (15.2% IAA). Median age at diagnosis ranged from 9.9 years in GCK-MODY (Q1-Q3: 6.2-13.1 years) and INS-MODY (2.7-13.7 years) to 14.3 years (5.0-17.1) in KCNJ11-MODY. Frequency of oral antidiabetic agents (OAD) use increased and insulin decreased in HNF4A-MODY (OAD: 18% to 39%, insulin: 34% to 23%) and in HNF1A-MODY (OAD: 18% to 31%, insulin: 35% to 25%). ABCC8-MODY was characterized by a decrement in nonpharmacological treatment (26% to 16%) and "insulin only" treatment (53% to 42%), while the proportion of individuals treated with OAD but no insulin increased from 0% to 21%.

CONCLUSIONS

Our results indicate that some teams caring for individuals with MODY are hesitant with regard to current recommendations. Registries are an essential source of information and provide a basis for discussing treatment guidelines for MODY.

Insulin Secretion Defect in Children and Adolescents with Obesity: Clinical and Molecular Genetic Characterization

Introduction

Childhood obesity is increasing worldwide and presents as a global health issue due to multiple metabolic comorbidities. About 1% of adolescents with obesity develop type 2 diabetes (T2D); however, little is known about the genetic and pathophysiological background at young age. The objective of this study was to assess the prevalence of impaired glucose regulation (IGR) in a large cohort of children and adolescents with obesity and to characterize insulin sensitivity and insulin secretion. We also wanted to investigate adolescents with insulin secretion disorder more closely and analyze possible candidate genes of diabetes in a subcohort.

Methods

We included children and adolescents with obesity who completed an oral glucose tolerance test (OGTT, glucose + insulin) in the outpatient clinic. We calculated Matsuda index, the area under the curve (AUC (Ins/Glu)), and an oral disposition index (ISSI-2) to estimate insulin resistance and beta-cell function. We identified patients with IGR and low insulin secretion (maximum insulin during OGTT < 200 mU/l) and tested a subgroup using next generation sequencing to identify possible mutations in 103 candidate genes.

Results

The total group consisted of 903 children and adolescents with obesity. 4.5% showed impaired fasting glucose, 9.4% impaired glucose tolerance, and 1.2% T2D. Matsuda index and Total AUC (Ins/Glu) showed a hyperbolic relationship. Out of 39 patients with low insulin secretion, we performed genetic testing on 12 patients. We found five monogenetic defects (ABCC8 (n = 3), GCK (n = 1), and GLI2/PTF1A (n = 1)).

Conclusion

Using surrogate parameters of beta-cell function and insulin resistance can help identify patients with insulin secretion disorder. A prevalence of 40% mutations of known diabetes genes in the subgroup with low insulin secretion suggests that at least 1.7% of patients with adolescent obesity have monogenic diabetes. A successful molecular genetic diagnosis can help to improve individual therapy.

A synonymous KCNJ11 variant leading to MODY13: A case report and literature review

Background

Maturity-onset diabetes of the young, type 13 (MODY13) is a specific subclass of monogenic diabetes mellitus that does not exhibit the typical clinical manifestations of diabetes, necessitating the use of genetic testing for accurate diagnosis. With the progression of monogenic diabetes and MODY, the number of reported MODY13 cases has reached a minimum of 22. Nevertheless, there remains a dearth of information regarding patients diagnosed with MODY13 presenting synonymous variants.

Case presentation

This study presents a description of the clinical and genetic features of a 9-year-old male patient diagnosed with MODY13. A noteworthy finding in this case was the occurrence of a "separation phenomenon" between C-peptide and insulin during the standard meal test. Whole exome sequencing (WES) identified a KCNJ11 c.843C > T (p.L281=) mutation in exon 1, which contradicted the previously reported phenotype. Following the onset of ketosis, the patient underwent insulin therapy for a duration of one month, during which the insulin dosage was gradually modified based on blood glucose levels. In order to maintain normoglycemia, he adhered to a diabetic dietary regimen and participated in 1-2 h of moderate exercise daily.

Conclusion

The study implies that patient with KCNJ11 variant shows a "separation phenomenon" between C-peptide and insulin in standard meal test. Our report also enriched the genotype and phenotype spectrums of MODY13 and highlighted the importance of genetic testing in patients without characteristic clinical symptoms of diabetes.

Case report: Better late than never, but sooner is better: switch from CSII to sulfonylureas in two patients with neonatal diabetes due to KCNJ11 variants

Neonatal diabetes mellitus (NDM) is a rare genetic disease characterized by severe hyperglycemia requiring insulin therapy with onset mostly within the first 6 months and rarely between 6-12 months of age. The disease can be classified into transient (TNDM) or permanent neonatal diabetes mellitus (PNDM), or it can be a component of a syndrome. The most frequent genetic causes are abnormalities of the 6q24 chromosomal region and mutations of the ABCC8 or KCNJ11 genes coding for the pancreatic beta cell's potassium channel (KATP). After the acute phase, patients with ABCC8 or KCNJ11 mutations treated with insulin therapy can switch to hypoglycemic sulfonylureas (SU). These drugs close the KATP channel binding the SUR1 subunit of the potassium channel and restoring insulin secretion after a meal. The timing of this switch can be different and could affect long-term complications. We describe the different management and clinical outcome over the time of two male patients with NDM due to KCNJ11 pathogenetic variants. In both cases, continuous subcutaneous insulin infusion pumps (CSII) were used to switch therapy from insulin to SU, but at different times after the onset. The two patients kept adequate metabolic control after the introduction of glibenclamide; during the treatment, insulin secretion was evaluated with c-peptide, fructosamine, and glycated hemoglobin (HbA1c), which were within the normal range. In neonates or infants with diabetes mellitus, genetic testing is an indispensable diagnostic tool and KCNJ11 variants should be considered. A trial of oral glibenclamide must be considered, switching from insulin, the first line of NDM treatment. This therapy can improve neurological and neuropsychological outcomes, in particular in the case of earlier treatment initiation. A new modified protocol with glibenclamide administered several times daily according to continuous glucose monitoring profile indications, was used. Patients treated with glibenclamide maintain good metabolic control and prevent hypoglycemia, neurological damage, and apoptosis of beta cells during long-term administration.

Next Generation Sequencing Analysis of MODY-X Patients: A Case Report Series

BACKGROUND

Classic criteria for a maturity-onset diabetes of the young (MODY) diagnosis are often unable to identify all subjects, and traditional Sanger sequencing, using a candidate gene approach, leads to a high prevalence of missed genetic diagnosis, classified as MODY-X. Next generation sequencing (NGS) panels provide a highly sensitive method even for rare forms.

METHODS

We investigated 28 pediatric subjects suspected for MODY-X, utilizing a 15-gene NGS panel for monogenic diabetes (MD).

RESULTS

NGS detected variants of uncertain significance (VUS), likely pathogenic or pathogenic for rarer subtypes of MODY, in six patients. We found variants in the wolframin gene (WFS1), traditionally not considered in MD genetic screening panels, in three patients; KCNJ11 gene mutation, typically responsible for neonatal diabetes and rarely causing isolated diabetes in adolescents; INS gene mutation; a variant in the HNF1B gene in a young male with diabetes on sulfonylurea treatment.

CONCLUSION

In our cohort, the availability of an NGS panel for MD was determined for the correct identification of MD subtypes in six patients with MODY-X. Our study underlines how a precise diagnosis utilizing NGS may have an impact on the management of different forms of MODY and, thus, lead to a tailored treatment and enable genetic counselling of other family members.