Monogenic Diabetes in Children and Adolescents: Recognition and Treatment Options

Comparison of the optical coherence tomography-angiography (OCT-A) vascular measurements between molecularly confirmed MODY and age-matched healthy controls

AIMS

Previous structural, vascular density, and perfusion studies have mostly comprised type 1 and type 2 diabetes, even in the absence of retinopathy. The current study aimed to compare macular vessel density (VD) measurements between maturity-onset diabetes of the young (MODY) patients and controls.

METHODS

The macular VD of superficial, deep retina, and choriocapillaris (CC), and central macular thickness (CMT), foveal avascular zone (FAZ), FAZ perimetry, VD of the total retina at 300 µm around the FAZ (FD), and acirculatory index (AI) measurements were taken and analyzed via OCT-A (RTVue XR 100-2 Avanti, AngioVue) and were compared between molecularly confirmed MODY (glucokinase (GCK) variants) patients and healthy controls.

RESULTS

Twenty-five MODY patients and 30 healthy controls were included in the study. The mean plasma hemoglobin A1c level in the MODY group was 6.39 ± 0.38. The mean age was 13.8 ± 2.1 in the MODY group and was 12.6 ± 2.5 years among controls. There was no significant difference in terms of the age, superficial and deep retinal VD, FAZ, FAZ perimetry, CMT, FD, or AI between the groups. Compared to the healthy controls, a slight but significant increase in the CC-VD was detected in the MODY group, but only in the parafoveal and perifoveal regions (p = 0.034, p = 0.009).

CONCLUSION

The significant CC-VD increase in the MODY group might be associated with hyperglycemia and/or relatively poor and vulnerable peripheral vascular CC perfusion compared to the central. Previous thickness and VD results of childhood or adolescent diabetes were distributed in a wider range, suggesting that various factors, including some not yet clearly defined, may affect the choroidal vasculature independently of glycemia or as a contributing factor.

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.

Heterozygous missense variant in GLI2 impairs human endocrine pancreas development

Missense variants are the most common type of coding genetic variants. Their functional assessment is fundamental for defining any implication in human diseases and may also uncover genes that are essential for human organ development. Here, we apply CRISPR-Cas9 gene editing on human iPSCs to study a heterozygous missense variant in GLI2 identified in two siblings with early-onset and insulin-dependent diabetes of unknown cause. GLI2 is a primary mediator of the Hedgehog pathway, which regulates pancreatic β-cell development in mice. However, neither mutations in GLI2 nor Hedgehog dysregulation have been reported as cause or predisposition to diabetes. We establish and study a set of isogenic iPSC lines harbouring the missense variant for their ability to differentiate into pancreatic β-like cells. Interestingly, iPSCs carrying the missense variant show altered GLI2 transcriptional activity and impaired differentiation of pancreatic progenitors into endocrine cells. RNASeq and network analyses unveil a crosstalk between Hedgehog and WNT pathways, with the dysregulation of non-canonical WNT signaling in pancreatic progenitors carrying the GLI2 missense variant. Collectively, our findings underscore an essential role for GLI2 in human endocrine development and identify a gene variant that may lead to diabetes.

Evaluation of Dry Eye Disease Characteristics of Children With Type 1 and Type 2 Diabetes Mellitus and MODY

PURPOSE

To assess dry eye disease characteristics of pediatric patients with diabetes.

METHODS

Twenty-one patients with type-1 diabetes mellitus (DM), 20 with type-2 DM, 19 with maturity-onset diabetes of the young (MODY), and 20 control participants were included in the study. Ocular Surface Disease Index (OSDI) questionnaire, tear film break-up time (TBUT) analysis, Schirmer test with anesthesia, and conjunctival impression cytologic analysis were performed.

RESULTS

In Group 1, the Schirmer test and TBUT values were lower than the control group. In groups 1 to 3, OSDI scores were higher than the control group. In Groups 1 and 2, the goblet cell density was lower than the control group.

CONCLUSIONS

Dry eye parameters of all three diabetic groups were adversely affected in favor of dry eye disease. Children with MODY have increased OSDI scores. Alterations in the conjunctival impression cytology were observed more prominently in patients with type-1 DM.

Challenges in Pediatric Diabetes Classification: A Case Report

Type 2 diabetes (T2DM) incidence and prevalence are increasing in pediatrics. All children aged > 10 years or postpubertal should be screened in primary care for T2DM if they are overweight with one risk factor or have signs of insulin resistance or associated conditions. Classifying pediatric diabetes is challenging. An accurate, timely diagnosis is critical to optimize care, as children with T2DM are at risk for more severe disease as adults. We describe a 10-year-old female referred to endocrine following abnormal laboratory results in primary care. Despite the initial presentation of diabetic ketoacidosis, the child was diagnosed with T2DM.

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.

Whole-exome sequencing reveals novel variants of monogenic diabetes in Tunisia: impact on diagnosis and healthcare management

Introduction: Monogenic diabetes (MD) accounts for 3%-6% of all cases of diabetes. This prevalence is underestimated due to its overlapping clinical features with type 1 and type 2 diabetes. Hence, genetic testing is the most appropriate tool for obtaining an accurate diagnosis. In Tunisia, few cohorts of MD have been investigated until now. The aim of this study is to search for pathogenic variants among 11 patients suspected of having MD in Tunisia using whole-exome sequencing (WES). Materials and methods: WES was performed in 11 diabetic patients recruited from a collaborating medical center. The pathogenicity of genetic variation was assessed using combined filtering and bioinformatics prediction tools. The online ORVAL tool was used to predict the likelihood of combinations of pathogenic variations. Then, Sanger sequencing was carried out to confirm likely pathogenic predicted variants among patients and to check for familial segregation. Finally, for some variants, we performed structural modeling to study their impact on protein function. Results: We identified novel variants related to MD in Tunisia. Pathogenic variants are located in several MODY and non-MODY genes. We highlighted the presence of syndromic forms of diabetes, including the Bardet-Biedl syndrome, Alström syndrome, and severe insulin resistance, as well as the presence of isolated diabetes with significantly reduced penetrance for Wolfram syndrome-related features. Idiopathic type 1 diabetes was also identified in one patient. Conclusion: In this study, we emphasized the importance of genetic screening for MD in patients with a familial history of diabetes, mainly among admixed and under-represented populations living in low- and middle-income countries. An accurate diagnosis with molecular investigation of MD may improve the therapeutic choice for better management of patients and their families. Additional research and rigorous investigations are required to better understand the physiopathological mechanisms of MD and implement efficient therapies that take into account genomic context and other related factors.

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.

eQTL mapping in fetal-like pancreatic progenitor cells reveals early developmental insights into diabetes risk

The impact of genetic regulatory variation active in early pancreatic development on adult pancreatic disease and traits is not well understood. Here, we generate a panel of 107 fetal-like iPSC-derived pancreatic progenitor cells (iPSC-PPCs) from whole genome-sequenced individuals and identify 4065 genes and 4016 isoforms whose expression and/or alternative splicing are affected by regulatory variation. We integrate eQTLs identified in adult islets and whole pancreas samples, which reveal 1805 eQTL associations that are unique to the fetal-like iPSC-PPCs and 1043 eQTLs that exhibit regulatory plasticity across the fetal-like and adult pancreas tissues. Colocalization with GWAS risk loci for pancreatic diseases and traits show that some putative causal regulatory variants are active only in the fetal-like iPSC-PPCs and likely influence disease by modulating expression of disease-associated genes in early development, while others with regulatory plasticity likely exert their effects in both the fetal and adult pancreas by modulating expression of different disease genes in the two developmental stages.

Atypical diabetes with spontaneous remission associated with systemic lupus erythematosus in an adolescent girl of African ancestry, a case report

BACKGROUND

New-onset diabetes in youth encompasses type 1 diabetes, type 2 diabetes, monogenic diabetes, and rarer subtypes like Type B insulin resistance syndrome and ketosis-prone atypical diabetes in African populations. Some cases defy classification, posing management challenges. Here, we present a case of a unique, reversible diabetes subtype.

CASE PRESENTATION

We describe an adolescent African girl recently diagnosed with systemic lupus erythematosus. At age 15, she presented with ketoacidosis, HbA1c of 108.7 mmol/mol (12.1%), and positive anti-insulin antibodies. Initially diagnosed with type 1 diabetes, insulin was prescribed. Due to the presence of obesity and signs of insulin resistance, we added metformin. Concurrently, she received treatment for lupus with hydroxychloroquine, mycophenolate mofetil, and prednisone. After discharge, she stopped insulin due to cultural beliefs. Five months later, her glycemia and HbA1c normalized (37 mmol/mol or 5.5%) without insulin, despite corticosteroid therapy and weight gain. Autoantibodies normalized, and lupus activity decreased. Genetic testing for monogenic diabetes was negative, and the type 1 genetic risk score was exceptionally low.

CONCLUSIONS

We present a complex, reversible diabetes subtype. Features suggest an autoimmune origin, possibly influenced by overlapping HLA risk haplotypes with lupus. Lupus treatment or immunomodulation may have impacted diabetes remission. Ancestry-tailored genetic risk scores are currently designed to improve diagnostic accuracy.

Linkage analysis using whole exome sequencing data implicates SLC17A1, SLC17A3, TATDN2 and TMEM131L in type 1 diabetes in Kuwaiti families

Type 1 diabetes (T1D) is characterized by the progressive destruction of pancreatic β-cells, leading to insulin deficiency and lifelong dependency on exogenous insulin. Higher estimates of heritability rates in monozygotic twins, followed by dizygotic twins and sib-pairs, indicate the role of genetics in the pathogenesis of T1D. The incidence and prevalence of T1D are alarmingly high in Kuwait. Consanguineous marriages account for 50-70% of all marriages in Kuwait, leading to an excessive burden of recessive allele enrichment and clustering of familial disorders. Thus, genetic studies from this Arab region are expected to lead to the identification of novel gene loci for T1D. In this study, we performed linkage analyses to identify the recurrent genetic variants segregating in high-risk Kuwaiti families with T1D. We studied 18 unrelated Kuwaiti native T1D families using whole exome sequencing data from 86 individuals, of whom 37 were diagnosed with T1D. The study identified three potential loci with a LOD score of ≥ 3, spanning across four candidate genes, namely SLC17A1 (rs1165196:pT269I), SLC17A3 (rs942379: p.S370S), TATDN2 (rs394558:p.V256I), and TMEM131L (rs6848033:p.R190R). Upon examination of missense variants from these genes in the familial T1D dataset, we observed a significantly increased enrichment of the genotype homozygous for the minor allele at SLC17A3 rs56027330_p.G279R accounting for 16.2% in affected children from 6 unrelated Kuwaiti T1D families compared to 1000 genomes Phase 3 data (0.9%). Data from the NephQTL database revealed that the rs1165196, rs942379, rs394558, and rs56027330 SNPs exhibited genotype-based differential expression in either glomerular or tubular tissues. Data from the GTEx database revealed rs942379 and rs394558 as QTL variants altering the expression of TRIM38 and IRAK2 respectively. Global genome-wide association studies indicated that SLC17A1 rs1165196 and other variants from SLC17A3 are associated with uric acid concentrations and gout. Further evidence from the T1D Knowledge portal supported the role of shortlisted variants in T1D pathogenesis and urate metabolism. Our study suggests the involvement of SLC17A1, SLC17A3, TATDN2, and TMEM131L genes in familial T1D in Kuwait. An enrichment selection of genotype homozygous for the minor allele is observed at SLC17A3 rs56027330_p.G279R variant in affected members of Kuwaiti T1D families. Future studies may focus on replicating the findings in a larger T1D cohort and delineate the mechanistic details of the impact of these novel candidate genes on the pathophysiology of T1D.

Next Generation Sequencing (NGS) Target Approach for Undiagnosed Dysglycaemia

Next-generation sequencing (NGS) has revolutionized the field of genomics and created new opportunities for basic research. We described the strategy for the NGS validation of the "dysglycaemia panel" composed by 44 genes related to glucose metabolism disorders (MODY, Wolfram syndrome) and familial renal glycosuria using Ion AmpliSeq technology combined with Ion-PGM. Anonymized DNA of 32 previously genotyped cases with 33 different variants were used to optimize the methodology. Standard protocol was used to generate the primer design, library, template preparation, and sequencing. Ion Reporter tool was used for data analysis. In all the runs, the mean coverage was over 200×. Twenty-nine out of thirty three variants (96.5%) were detected; four frameshift variants were missed. All point mutations were detected with high sensitivity. We identified three further variants of unknown significance in addition to pathogenic mutations previously identified by Sanger sequencing. The NGS panel allowed us to identify pathogenic variants in multiple genes in a short time. This could help to identify several defects in children and young adults that have to receive the genetic diagnosis necessary for optimal treatment. In order not to lose any pathogenic variants, Sanger sequencing is included in our analytical protocol to avoid missing frameshift variants.

Analysis of Corneal Deformation in Paediatric Patients Affected by Maturity Onset Diabetes of the Young Type 2

BACKGROUND

To evaluate corneal deformation in Maturity Onset Diabetes of the Young type 2 (MODY2), paediatric subjects were analysed using a Scheimpflug-based device. The purpose of this analysis was to find new biomarkers for MODY2 disease and to gain a better understanding of the pathogenesis of the disease.

METHODS

A total of 15 patients with genetic and metabolic diagnoses of MODY2 (mean age 12.8 ± 5.66 years) and 15 age-matched healthy subjects were included. The biochemical and anthropometric data of MODY2 patients were collected from clinical records, and a complete ophthalmic check with a Pentacam HR EM-3000 Specular Microscope and Corvis ST devices was performed in both groups.

RESULTS

Highest concavity (HC) deflection length, Applanation 1 (A1) deflection amplitude, and A1 deflection area showed significantly lower values in MODY2 patients compared to healthy subjects. A significant positive correlation was observed between Body Mass Index (BMI) and HC deflection area and between waist circumference (WC) and the following parameters: maximum deformation amplitude, HC deformation amplitude, and HC deflection area. The glycosylated hemoglobin level (HbA1c) showed a significant positive correlation with Applanation 2 time and HC time.

CONCLUSIONS

The obtained results show, for the first time, differences regarding corneal distortion features in the MODY2 population compared with healthy eyes.

"Pesto" Mutation: Phenotypic and Genotypic Characteristics of Eight GCK/MODY Ligurian Patients

Maturity Onset Diabetes of the Young (MODY) is a monogenic form of diabetes mellitus (DM) that accounts for around 2-5% of all types of diabetes. Autosomal dominant inheritance in pathogenic variations of 14 genes related to β-cell functions can lead to monogenic types of diabetes. In Italy, GCK/MODY is the most frequent form and it is caused by mutations of the glucokinase (GCK). Patients with GCK/MODY usually have stable mild fasting hyperglycaemia with mildly elevated HbA1c levels and rarely need pharmacological treatment. Molecular analysis of the GCK coding exons was carried out by Sanger sequencing in eight Italian patients. All the probands were found to be heterozygous carriers of a pathogenic gross insertion/deletion c.1279_1358delinsTTACA; p.Ser426_Ala454delinsLeuGln. It was previously described for the first time by our group in a large cohort of Italian GCK/MODY patients. The higher levels of HbA1c (6.57% vs. 6.1%), and the higher percentage of patients requiring insulin therapy (25% vs. 2%) compared to the previously studied Italian patients with GCK/MODY, suggest that the mutation discovered could be responsible for a clinically worse form of GCK/MODY. Moreover, as all the patients carrying this variant share an origin from the same geographic area (Liguria), we postulate a possible founder effect and we propose to name it the "pesto" mutation.

An effective preselection criterion for MODY with an increasingly positive genetic testing rate by NGS: results from two cohorts of Chinese children

The purpose of this study was to determine the frequency of maturity-onset diabetes of the young (MODY) in two selected cohorts of Chinese children with diabetes and clinically suspected MODY, using next-generation sequencing (NGS). Ninety-three children who met the comprehensive criteria of suspected MODY were enrolled in two cohorts. A custom NGS panel or a whole exon group was used for sequencing. We identified 55/93 (59.1%) children with pathogenic and likely pathogenic MODY variants. Forty-two (76.3%) were confirmed to have the GCK (MODY2) mutation. Additionally, five had the HNF1A (MODY3), two the HNF1B (MODY5), one the 17q12 microdeletion (MODY5), two the HNF4A (MODY1), two the ABCC8 (MODY12), and one the PDX1 mutation (MODY4). Of these, 13 novel variants were detected in different genes. By comparing the gene-positive with gene-negative children, we found that discriminatory factors for MODY at diagnosis included lower HbA1c [7.4% vs. 10.2% (53 vs. 86 mmol/mol); P = 0.002], lower body mass index z score (0.2 vs. 1.0; P = 0.01), lower onset age (8.1 vs. 11.2 years; P = 0.001), and lower C-peptide (1.4 vs. 2.5 ng/mL; P = 0.02). In conclusion, the criteria used in this study for screening MODY are effective, and MODY2 is the most common subtype (76%), followed by MODY3 and MODY5. Some rare MODY subtypes have been reported in Chinese children.NEW & NOTEWORTHY We proved the clinical suspicion of maturity-onset diabetes of the young (MODY) according to the comprehensive criterion for next-generation sequencing testing, which helps to identify both common and rare MODYs, leading to accurate diagnosis and personalized treatment.

IER3IP1 is critical for maintaining glucose homeostasis through regulating the endoplasmic reticulum function and survival of β cells

Recessive mutations in IER3IP1 (immediate early response 3 interacting protein 1) cause a syndrome of microcephaly, epilepsy, and permanent neonatal diabetes (MEDS). IER3IP1 encodes an endoplasmic reticulum (ER) membrane protein, which is crucial for brain development; however, the role of IER3IP1 in β cells remains unknown. We have generated two mouse models with either constitutive or inducible IER3IP1 deletion in β cells, named IER3IP1-βKO and IER3IP1-iβKO, respectively. We found that IER3IP1-βKO causes severe early-onset, insulin-deficient diabetes. Functional studies revealed a markedly dilated β-cell ER along with increased proinsulin misfolding and elevated expression of the ER chaperones, including PDI, ERO1, BiP, and P58IPK. Islet transcriptome analysis confirmed by qRT-PCR revealed decreased expression of genes associated with β-cell maturation, cell cycle, and antiapoptotic genes, accompanied by increased expression of antiproliferation genes. Indeed, multiple independent approaches further demonstrated that IER3IP1-βKO impaired β-cell maturation and proliferation, along with increased condensation of β-cell nuclear chromatin. Inducible β-cell IER3IP1 deletion in adult (8-wk-old) mice induced a similar diabetic phenotype, suggesting that IER3IP1 is also critical for function and survival even after β-cell early development. Importantly, IER3IP1 was decreased in β cells of patients with type 2 diabetes (T2D), suggesting an association of IER3IP1 deficiency with β-cell dysfunction in the more-common form of diabetes. These data not only uncover a critical role of IER3IP1 in β cells but also provide insight into molecular basis of diabetes caused by IER3IP1 mutations.

Pancreatic beta-cell function dynamics in youth with GCK, HNF1A, and KCNJ11 genes mutations during mixed meal tolerance test

OBJECTIVE

The aims were (1) to assess beta-cell function in GCK diabetes patients over 2-year period; (2) to evaluate the dynamics of beta-cell function in HNF1A and KCNJ11 patients after treatment optimization; using mixed meal tolerance test (MMTT) as a gold standard for non-invasive beta-cell function assessment.

RESEARCH DESIGN AND METHODS

Twenty-two GCK diabetes patients, 22 healthy subjects, 4 patients with HNF1A and 2 with KCNJ11 were recruited. Firstly, beta-cell function was compared between GCK patients versus controls; the dynamics of beta-cell function were assessed in GCK patients with two MMTTs in 2-year period. Secondly, the change of beta-cell function was evaluated in HNF1A and KCNJ11 patients after successful treatment optimization in 2-year period.

RESULTS

GCK diabetes patients had lower area under the curve (AUC) of C-peptide (CP), average CP and peak CP compared to controls. Also, higher levels of fasting, average, peak and AUC of glycemia during MMTT were found in GCK patients compared to healthy controls. No significant changes in either CP or glycemia dynamics were observed in GCK diabetes group comparing 1st and 2nd MMTTs. Patients with HNF1A and KCNJ11 diabetes had significantly improved diabetes control 2 years after the treatment was optimized (HbA1c 7.1% vs. 5.9% [54 mmol/mol vs. 41 mmol/mol], respectively, p = 0.028). Higher peak CP and lower HbA1c were found during 2nd MMTT in patients with targeted treatment compared to the 1st MMTT before the treatment change.

CONCLUSION

In short-term perspective, GCK diabetes group revealed no deterioration of beta-cell function. Individualized treatment in monogenic diabetes showed improved beta-cell function.

Type 2 diabetes in children and adolescents: distinct characteristics and evidence-based management

PURPOSE

Since the dramatic rise of obesity prevalence in childhood and adolescence has contributed to increased rates of type 2 diabetes (T2D) in youth, we sought to explore current evidence-based management options for pediatric T2D patients.

METHODS

A comprehensive literature search was performed for studies of T2D in childhood and adolescence until September 2021.

RESULTS

Special pathophysiological and diagnostic characteristics of T2D in this age are presented, while the main focus of the article is on management. Lifestyle interventions with healthy diet and exercise are of great importance for the treatment of T2D in children and adolescents. Metformin and insulin remain the traditional therapeutical means, while liraglutide recently gained indication for children older than 10 years both in USA and Europe. Data on the use, efficacy, safety and therapeutic considerations of other pharmacological treatments in children and adolescents with T2D are critically discussed.

CONCLUSION

Although many new and promising therapeutic strategies have been introduced during recent years for the management of T2D in adults, available therapeutic options for the management of pediatric T2D remain limited.

Study of ten causal genes in Turkish patients with clinically suspected maturity-onset diabetes of the young (MODY) using a targeted next-generation sequencing panel

BACKGROUND

Maturity-onset diabetes of the young (MODY), which is the most common cause of monogenic diabetes, has an autosomal dominant pattern of inheritance and exhibits marked clinical and genetic heterogeneity. The aim of the current study was to investigate molecular defects in patients with clinically suspected MODY using a next-generation sequencing (NGS)-based targeted gene panel.

METHODS

Candidate patients with clinical suspicion of MODY and their parents were included in the study. Molecular genetic analyses were performed on genomic DNA by using NGS. A panel of ten MODY-causal genes involving GCK, HNF1A, HNF1B, HNF4A, ABCC8, CEL, INS, KCNJ11, NEUROD1, PDX1 was designed and subsequently implemented to screen 40 patients for genetic variants.

RESULTS

Ten different pathogenic or likely pathogenic variants were identified in MODY-suspected patients, with a diagnostic rate of 25%. Three variants of uncertain significance were also detected in the same screen. A novel pathogenic variant in the gene HNF1A (c.505_506delAA [p.Lys169AlafsTer18]) was described for the first time in this report. Intriguingly, we were able to detect variants associated with rare forms of MODY in our study population.

CONCLUSIONS

Our results suggest that in heterogenous diseases such as MODY, NGS analysis enables accurate identification of underlying molecular defects in a timely and cost-effective manner. Although MODY accounts for 2-5% of all diabetic cases, molecular genetic diagnosis of MODY is necessary for optimal long-term treatment and prognosis as well as for effective genetic counseling.

Precision Diabetes: Lessons Learned from Maturity-Onset Diabetes of the Young (MODY)

Maturity‐onset of diabetes of the young (MODY) are monogenic forms of diabetes characterized by early onset diabetes with autosomal dominant inheritance. Since its first description about six decades ago, there have been significant advancements in our understanding of MODY from clinical presentations to molecular diagnostics and therapeutic responses. The prevalence of MODY is estimated as at least 1.1–6.5% of the pediatric diabetes population with a high degree of geographic variability that might arise from several factors in the criteria used to ascertain cases. GCK‐MODY, HNF1A‐MODY, and HNF4A‐MODY account for >90% of MODY cases. While some MODY forms do not require treatment (i.e., GCK‐MODY), some others are highly responsive to oral agents (i.e., HNF1A‐MODY). The risk of micro‐ and macro‐vascular complications of diabetes also differ significantly between MODY forms. Despite its high clinical impact, 50–90% of MODY cases are estimated to be misdiagnosed as type 1 or type 2 diabetes. Although there are many clinical features suggestive of MODY diagnosis, there is no single clinical criterion. An online MODY Risk Calculator can be a useful tool for clinicians in the decision‐making process for MODY genetic testing in some situations. Molecular genetic tests with a commercial gene panel should be performed in cases with a suspicion of MODY. Unresolved atypical cases can be further studied by exome or genome sequencing in a clinical or research setting, as available.

Expression and mechanism of microRNA 195 in diabetic retinopathy

We aimed to explore the role of microRNA 195 (miR-195) in diabetic retinopathy (DR). From January 2019 to July 2020, 50 patients with DR undergoing vitrectomy and 40 patients with idiopathic macular holes undergoing vitrectomy were selected as the observation group (OG) and control group (CG), respectively. The mRNA and protein expression levels of miR-195, SIRT1, BAX, and BCL-2 were detected in the retinal tissues obtained from the two groups during surgery. In addition, human retinal endothelial cells and human dermal microvascular endothelial cells were cultured in a high-glucose environment to detect the targeted relationship between miR-195 and SIRT1; determine the mRNA and protein expression levels of SIRT1, BAX, and BCL-2 after miR-195 knockdown; and assess the levels of cell proliferation and apoptosis. In OG, the mRNA and protein expression levels of miR-195 and BAX were high, whereas those of BCL-2 and SIRT1 were low. Moreover, we detected a targeted relationship between miR-195 and SIRT1. Conversely, miR-195 knockdown led to the downregulation of the mRNA and protein expression levels of BAX and the upregulation of the mRNA and protein expression levels of SIRT1 and BCL-2 as well as improvement in cell growth and a decrease in the apoptosis rate. miR-195 is overexpressed in DR, and its targeted relationship with SIRT1 inhibits the growth of cells in the retina and accelerates apoptosis.

Efficacy of epalrestat combined with alprostadil for diabetic nephropathy and its impacts on renal fibrosis and related factors of inflammation and oxidative stress

OBJECTIVE

To explore the efficacy of epalrestat (Ep) combined with alprostadil (Alp) in the treatment of diabetic nephropathy (DN) and its impacts on renal fibrosis (RF) and inflammation and oxidative stress (OS)-related factors.

METHODS

In this retrospective study, 120 patients with DN treated in the Cangzhou Central Hospital from January 2020 to January 2021 were selected as the research subjects. Among them, 80 cases treated with Ep combined with Alp were assigned to group A, and the rest 40 patients treated with Alp only were assigned to group B. The two groups were compared with respect to the following items: serum OS indexes (malondialdehyde, MDA; superoxide dismutase, SOD; total antioxidant capacity, TAOC), inflammatory factors (tumor necrosis factor-α, TNF-α; interleukin-2, IL-2), RF index transforming growth factor-β1 (TGF-β1), urinary protein indexes (urinary albumin excretion, UAE; serum albumin, ALB), blood glucose (fasting blood glucose, FBG), fasting C-peptide, postprandial 2hC peptide levels, overall response rate (ORR) and incidence of adverse reactions.

RESULTS

Compared with group B, the levels of MDA, TNF-α, IL-2 and TGF-β1 were lower, while SOD and TAOC were higher in group A. In addition, ALB was higher, while UAE and FBG were lower in group A as compared with group B. Moreover, group A had a higher ORR and fewer adverse reactions as compared with group B.

CONCLUSION

The combined therapy of Ep and Alp is more effective in the treatment of DN. This combination can effectively reduce RF and better alleviate inflammation and OS.

Meta-analysis of HNF1A-MODY3 variants among human population

Background

Previously, numerous case-control studies have highlighted variants responsible for Maturity onset diabetes of young (MODY). However, these studies have been conducted among diverse populations and hence yielded contradictory results. We, therefore, performed a meta-analysis to precisely find the association of SNPs with the disease for the HNF1A gene.

Objective

Meta-analysis of clinically defined studies deciphering mutations in the HNF1A gene responsible for the development of MODY3 was conducted among various populations to determine associations using statistical approaches.

Methods

The curation of 505 research articles published between the years 2000-2021 was carried out. Visualization of data-related protocols and statistical-analysis were conducted, which led to the identification of highly prevalent mutations among different populations (majorly Europe). Further comparison between the frequencies of the control (healthy population) and test (diseased population) dataset generated through curation was performed.

Results

We identified nine MODY3 mutations (rs587776825, rs1169288, rs1800574, rs2464196, rs137853244, rs137853238, rs587780357, rs137853240 and rs137853243) at the genome-wide significance level ( p < 5.0 × 10^-8). The present study confirmed that the data does not follow a normal distribution. Further, the data was confirmed to be a more homogenous type with frequencies having a significant association with the disease.

Conclusion

This meta-analysis found significant associations of mutations in HNF1A with MODY3, consistent with previous studies. Our findings should help elucidate the mutations in a compiled form responsible for causing MODY3.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-022-00975-8.

Genome Editing and Human Pluripotent Stem Cell Technologies for in vitro Monogenic Diabetes Modeling

Diabetes is a metabolic disease characterized by chronic hyperglycemia. Polygenic diabetes, which encompasses type-1 and type-2 diabetes, is the most prevalent kind of diabetes and is caused by a combination of different genetic and environmental factors, whereas rare phenotype monogenic diabetes is caused by a single gene mutation. Monogenic diabetes includes Neonatal diabetes mellitus and Maturity-onset diabetes of the young. The majority of our current knowledge about the pathogenesis of diabetes stems from studies done on animal models. However, the genetic difference between these creatures and humans makes it difficult to mimic human clinical pathophysiology, limiting their value in modeling key aspects of human disease. Human pluripotent stem cell technologies combined with genome editing techniques have been shown to be better alternatives for creating in vitro models that can provide crucial knowledge about disease etiology. This review paper addresses genome editing and human pluripotent stem cell technologies for in vitro monogenic diabetes modeling.

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

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

Diabetic kidney disease in children and adolescents: an update

Diabetic kidney disease (DKD), previously encountered predominantly in adult patients, is rapidly gaining center stage as a childhood morbidity and one that pediatric nephrologists are likely to encounter with increasing frequency. This is in large part due to the obesity epidemic and the consequent rise in type 2 diabetes in children and adolescents, as well as the more aggressive diabetes phenotype in today's youth with more rapid β-cell decline and faster development and progression of diabetes-related complications along with lower responsiveness to the treatments used in adults. DKD, an end-organ complication of diabetes, is at the very least a marker of, and more likely a predisposing factor for, the development of adverse cardiovascular outcomes and premature mortality in children with diabetes. On an optimistic note, several new therapeutic approaches are now available for the management of diabetes in adults, such as GLP1 receptor agonists, SGLT2 inhibitors, and DPP4 inhibitors, that have also been shown to have a favorable impact on cardiorenal outcomes. Also promising is the success of very low-energy diets in inducing remission of diabetes in adults. However, the addition of these pharmacological and dietary approaches to the management toolbox of diabetes and DKD in children and adolescents awaits thorough assessment of their safety and efficacy in this population. This review outlines the scope of diabetes and DKD, and new developments that may favorably impact the management of children and young adults with diabetes and DKD.

A case of monogenic diabetes mellitus caused by a novel heterozygous RFX6 nonsense mutation in a 14-year-old girl

OBJECTIVES

Monogenic diabetes mellitus (DM) is a single gene disorder, primarily characterized by impairment in the development or function of pancreatic beta cells.

CASE PRESENTATION

A 14-year-old girl was initially diagnosed with type 2 DM. The patient did not have any anti-islet autoantibody and showed acanthosis nigricans. She was managed with long-acting insulin and oral hypoglycemic agent, but HbA_1c was still 9.3% after 1 year of management. Her mother already had type 2 DM at 46-year-old and was on medication. Under the possibility of familial monogenic DM, targeted exome sequencing was performed which included 29 genes associated with monogenic DM. Nonsense mutation of the gene RFX6 (c.2661T>A, p.Tyr887∗) was found. After adding Glucagon-like peptide-1 (GLP-1) receptor agonist, HbA_1c improved from 8.8 to 6.8% and body mass index (BMI) also improved from 31.0 to 29.2 kg/m².

CONCLUSIONS

It may be worth investigating genetic etiology in early-onset autoantibody-negative DM for specific genetic diagnosis and better management.

Effect of high-quality nursing on blood glucose level, psychological state, and treatment compliance of patients with gestational diabetes mellitus

OBJECTIVE

This study was designed to determine the effect of high-quality nursing on patients with gestational diabetes mellitus (GDM).

METHODS

A total of 114 patients diagnosed with GDM in our hospital between December 2016 and December 2018 were enrolled, and assigned to a high-quality group (HQ group; n=64) and a normal group (Nor group; n=50). Patients in the HQ group were nursed under the high-quality nursing mode, while those in the Nor group were nursed under the routine nursing mode. The following items of all patients were determined: Blood glucose index, serum lipids index, insulin resistance index, mental health level, treatment compliance, total effective rate of diabetes mellitus treatment, incidence of adverse reactions, and satisfaction.

RESULTS

Compared with the Nor group, the HQ group showed higher levels of fasting blood glucose, 2-hour postprandial blood glucose, total cholesterol, triglyceride, low-density lipoprotein-cholesterol, and lower levels of high-density lipoprotein-cholesterol, and also showed lower Homa IR and incidence of adverse reactions, with lower Hamilton anxiety scale (HAMA) and Hamilton depression scale (HAMD) scores, and showed higher treatment compliance, total effective rate of diabetes mellitus treatment, and overall satisfaction.

CONCLUSION

High-quality nursing can effectively improve the blood glucose level and psychological state of patients with GDM, and contributes to higher treatment compliance.

NEUROD1 mutation in an Italian patient with maturity onset diabetes of the young 6: a case report

BACKGROUND

Maturity Onset Diabetes of the Young (MODY) is a monogenic, autosomal, dominant disease that results in beta-cells dysfunction with consequent hyperglycaemia. It represents a rare form of diabetes (1-2% of all the cases). Sulphonylureas (SUs) represent the first-line treatment for this form of diabetes mellitus. NEUROD1 is expressed by the nervous and the pancreatic tissues, and it is necessary for the proper development of beta cells. A neurogenic differentiation factor 1 (NEUROD1) gene mutation causes beta-cells dysfunction, inadequate insulin secretion, and hyperglycaemia (MODY 6).

CASE PRESENTATION

We have documented a new missense mutation (p.Met114Leu c.340A > C) of the NEUROD1 gene, pathogenetic for diabetes mellitus, in a 48 years-old man affected by diabetes since the age of 25 and treated with insulin basal-bolus therapy. Unfortunately, an attempt to replace rapid insulin with dapagliflozin has failed. However, after the genetic diagnosis of MODY6 and treatment with SUs, he was otherwise able to suspend rapid insulin and close glucose monitoring. Interestingly, our patient had an early onset dilated cardiomyopathy, though no data about cardiac diseases in patients with MODY 6 are available.

CONCLUSIONS

Diagnostic criteria for MODY can overlap with other kinds of diabetes and most cases of genetic diabetes are still misdiagnosed as diabetes type 1 or 2. We encourage to suspect this disease in patients with a strong family history of diabetes, normal BMI, early-onset, and no autoimmunity. The appropriate therapy simplifies disease management and improves the quality of the patient's life.

Multiallelic Rare Variants in BBS Genes Support an Oligogenic Ciliopathy in a Non-obese Juvenile-Onset Syndromic Diabetic Patient: A Case Report

Juvenile-onset diabetes may occur in the context of a rare syndromic presentation, suggesting a monogenic etiology rather than a common multifactorial diabetes. In the present study, we report the case of a young diabetic Tunisian patient presenting learning problems, speech deficits, short stature, brachydactyly, and a normal weight. Whole exome sequencing analysis revealed five heterozygous genetic variants in BBS1, BBS4, BBS8, MKS1, and CEP290. These genes are involved in the regulation of cilium biogenesis and function. We analyzed variant combinations pathogenicity using the recently developed ORVAL tool, and we hypothesized that cumulative synergetic effects of these variants could explain the syndromic phenotype observed in our patient. Therefore, our investigation suggested a genetic diagnosis of Bardet-Biedl syndrome with an oligogenic inheritance pattern rather than a monogenic diabetes. Although there is no curative therapy for this ciliopathy at the moment, a genetic diagnosis may offer other supportive care options, including the prevention of other possible clinical manifestations of this syndrome, mainly renal abnormalities, obesity, liver fibrosis, and hypertension, as well as the genetic counseling for family members.

The Epidemiology and Genetic Analysis of Children With Idiopathic Type 1 Diabetes in the State of Qatar

Context

Idiopathic type 1 diabetes is characterized by the absence of autoantibodies and the underlying mechanisms are not clear.

Objective

We aimed to study the epidemiology, describe the clinical characteristics, and report results of genetic studies in pediatric patients with idiopathic type 1 diabetes.

Methods

This was a prospective study of type 1 diabetes patients attending Sidra Medicine from 2018 to 2020. Autoantibodies (GAD65, IAA, IA-2A, and ZnT8) were measured and genetic testing was undertaken in patients negative for autoantibodies to rule out monogenic diabetes. Demographic and clinical data of patients with idiopathic type 1 diabetes were compared with patients with autoimmune type 1 diabetes.

Results

Of 1157 patients with type 1 diabetes, 63 were antibody-negative. Upon genome sequencing, 4 had maturity onset diabetes of the young (MODY), 2 had Wolfram syndrome, 1 had H syndrome, and 3 had variants of uncertain significance in MODY genes; 53 patients had idiopathic type 1 diabetes. The most common age of diagnosis was 10 to 14 years. C-peptide level was low but detectable in 30 patients (56.6%) and normal in 23 patients (43.4%) The average body mass index was in the normal range and 33% of the patients had a history of diabetic ketoacidosis (DKA).

Conclusion

Four percent of the children had idiopathic type 1 diabetes. There were statistically significant differences in the C-peptide level and insulin requirement between the 2 groups. DKA was less common in the idiopathic group. Mutations in MODY genes suggest the importance of autoantibody testing and genetic screening for known causes of monogenic diabetes in idiopathic type 1 diabetes. The mechanism of idiopathic type 1 diabetes is unknown but could be due to defects in antibody production or due to autoantibodies that are not yet detectable or discovered.

Genetic syndromes with diabetes: A systematic review

Previous reviews and clinical guidelines have identified 10-20 genetic syndromes associated with diabetes, but no systematic review has been conducted to date. We provide the first comprehensive catalog for syndromes with diabetes mellitus. We conducted a systematic review of MEDLINE, Embase, CENTRAL, PubMed, OMIM, and Orphanet databases for case reports, case series, and observational studies published between 1946 and January 15, 2020, that described diabetes mellitus in adults and children with monogenic or chromosomal syndromes. Our literature search identified 7,122 studies, of which 160 fulfilled inclusion criteria. Our analysis of these studies found 69 distinct diabetes syndromes. Thirty (43.5%) syndromes included diabetes mellitus as a cardinal clinical feature, and 56 (81.2%) were fully genetically elucidated. Sixty-three syndromes (91.3%) were described more than once in independent case reports, of which 59 (93.7%) demonstrated clinical heterogeneity. Syndromes associated with diabetes mellitus are more numerous and diverse than previously anticipated. While knowledge of the syndromes is limited by their low prevalence, future reviews will be needed as more cases are identified. The genetic etiologies of these syndromes are well elucidated and provide potential avenues for future gene identification efforts, aid in diagnosis and management, gene therapy research, and developing personalized medicine treatments.

Identification of Maturity-Onset-Diabetes of the Young (MODY) mutations in a country where diabetes is endemic

Genetic variants responsible for Maturity-Onset-Diabetes of the Young (MODY) in Kuwait were investigated. A newly established a National Referral Clinic, the Dasman Diabetes Institute (DDI-NRC), assessed forty-five members from 31 suspected MODY families by whole exome sequencing. Thirty-three of the 45 samples were independently sequenced at the DDI-NRI, Exeter University, UK (https://www.diabetesgenes.org/) using targeted 21-gene panel approach. Pathogenic mutations in GCK, HNF1A, HNF1B, HNF4A, and PDX1 confirmed MODY in 7 families, giving an overall positivity rate of 22.6% in this cohort. Novel variants were identified in three families in PDX1, HNF1B, and HNF1B. In this cohort, Multiplex Ligation-dependent Probe Amplification assay did not add any value to MODY variant detection rate in sequencing negative cases. In highly selected familial autoantibody negative diabetes, known MODY genes represent a minority and 77.3% of the familial cases have yet to have a causal variant described.

Monogenic Childhood Diabetes: Dissecting Clinical Heterogeneity by Next-Generation Sequencing in Maturity-Onset Diabetes of the Young

Diabetes is a common disorder with a heterogeneous clinical presentation and an enormous burden on health care worldwide. About 1-6% of patients with diabetes suffer from maturity-onset diabetes of the young (MODY), the most common form of monogenic diabetes with autosomal dominant inheritance. MODY is genetically and clinically heterogeneous and caused by genetic variations in pancreatic β-cell development and insulin secretion. We report here new findings from targeted next-generation sequencing (NGS) of 13 MODY-related genes. A sample of 22 unrelated pediatric patients with MODY and 13 unrelated healthy controls were recruited from a Turkish population. Targeted NGS was performed with Miseq 4000 (Illumina) to identify genetic variations in 13 MODY-related genes: HNF4A, GCK, HNF1A, PDX1, HNF1B, NEUROD1, KLF11, CEL, PAX4, INS, BLK, ABCC8, and KCNJ11. The NGS data were analyzed adhering to the Genome Analysis ToolKit (GATK) best practices pipeline, and variant filtering and annotation were performed. In the patient sample, we identified 43 MODY-specific genetic variations that were not present in the control group, including 11 missense mutations and 4 synonymous mutations. Importantly, and to the best of our knowledge, the missense mutations NEUROD1 p.D202E, KFL11 p.R461Q, BLK p.G248R, and KCNJ11 p.S385F were first associated with MODY in the present study. These findings contribute to the worldwide knowledge base on MODY and molecular correlates of clinical heterogeneity in monogenic childhood diabetes. Further comparative population genetics and functional genomics studies are called for, with an eye to discovery of novel diagnostics and personalized medicine in MODY. Because MODY is often misdiagnosed as type 1 or type 2 diabetes mellitus, advances in MODY diagnostics with NGS stand to benefit diabetes overall clinical care as well.

In celebration of a century with insulin - Update of insulin gene mutations in diabetes

Background

While insulin has been central to the pathophysiology and treatment of patients with diabetes for the last 100 years, it has only been since 2007 that genetic variation in the INS gene has been recognised as a major cause of monogenic diabetes. Both dominant and recessive mutations in the INS gene are now recognised as important causes of neonatal diabetes and offer important insights into both the structure and function of insulin. It is also recognised that in rare cases, mutations in the INS gene can be found in patients with diabetes diagnosed outside the first year of life.

Scope of Review

This review examines the genetics and clinical features of monogenic diabetes resulting from INS gene mutations from the first description in 2007 and includes information from 389 patients from 292 families diagnosed in Exeter with INS gene mutations. We discuss the implications for diagnosing and treating this subtype of monogenic diabetes.

Major Conclusions

The dominant mutations in the INS gene typically affect the secondary structure of the insulin protein, usually by disrupting the 3 disulfide bonds in mature insulin. The resulting misfolded protein results in ER stress and beta-cell destruction. In contrast, recessive INS gene mutations typically result in no functional protein being produced due to reduced insulin biosynthesis or loss-of-function mutations in the insulin protein. There are clinical differences between the two genetic aetiologies, between the specific mutations, and within patients with identical mutations.

•

Dominant and recessive mutations in the insulin (INS) gene are important causes of neonatal diabetes.

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Associated phenotypes are variable in terms of age at diabetes onset, birth weight and treatment requirements.

•

Dominant mutations affect the secondary structure of the insulin protein, resulting in beta-cell ER stress and destruction.

•

Recessive mutations result in reduced insulin biosynthesis or loss-of-function mutations of the insulin protein.

•

The studies of these forms of diabetes offer important insights into the structure, biosynthesis and secretion of insulin.

DPARD: rationale, design and initial results from the Dutch national diabetes registry

BACKGROUND

Treatment of diabetes mellitus has majorly improved over the past century, however, the disease burden is high and its prevalence still expanding. Further insight in the diabetes population is imperative to improve the quality of diabetes care by enhancement of knowledge-based diabetes management strategies. To this end, in 2017 a Dutch nationwide consortium of diabetologists, paediatric endocrinologists, and diabetes patients has founded a national outpatient diabetes care registry named Dutch Pediatric and Adult Registry of Diabetes (DPARD). We aim to describe the implementation of DPARD and to provide an overview of the characteristics of patients included during the first 2 years.

METHODS

For the DPARD cohort with long-term follow-up of observational nature, hospital data are gathered directly from electronic health records and securely transferred and stored. DPARD provides weekly updated clinical information on the diabetes population care on a hospital-level benchmarked against the national average.

RESULTS

Between November 2017 and January 2020, 20,857 patients were included from 8 (11%) Dutch hospitals with a level of care distribution representative of all diabetic outpatients in the Netherlands. Among patients with known diabetes type, 41% had type 1 diabetes, 51% type 2 diabetes, and 8% had diabetes due to other causes. Characteristics of the total patient population were similar to patients with unknown diabetes classification. HbA1c levels decreased over the years, while BMI levels showed an increase over time.

CONCLUSIONS

The national DPARD registry aims to facilitate investigation of prevalence and long-term outcomes of Dutch outpatients with diabetes mellitus and their treatment, thus allowing for quality improvement of diabetes care as well as allowing for comparison of diabetes care on an international level.

Type 2 Diabetes in Youth

The incidence of type 2 diabetes in children and adolescents in the United States rose at an annual rate of 4.8% between 2002-2003 and 2014-2015. Type 2 diabetes progresses more aggressively to complications than type 1 diabetes. For example, in one large epidemiological study, proliferative retinopathy affected 5.6% and 9.1% of children with type 1 and type 2 diabetes, respectively. Screening begins at age 10 or at onset of puberty, and is recommended among children with a BMI% ≥85 with risk factors such as a family history and belonging to a high risk racial or ethnic or racial group. HbA1C% is preferred for screening as it does not require fasting. As distinguishing between type 1 and type 2 diabetes is not straightforward, all children with new onset disease should undergo autoantibody testing. Results of lifestyle interventions for control of type 2 diabetes have been disappointing, but are still recommended for their educational value and the potential impact upon some participants. There is limited evidence for the benefit of newer mediations. Liraglutide, a GLP-1 agonist, however, has been shown to significantly reduce HbA1C% in one study and is now approved for children. Liraglutide should be considered as second line therapy.

Monogenic Diabetes in a Child with Cystic Fibrosis: A Case Report and Review of the Literature

Cystic fibrosis-related diabetes (CFRD) is associated with worsening pulmonary function, lower body mass index, increased infection frequency, and earlier mortality. While the incidence of CFRD is rising, its development in patients under the age of 10 years is uncommon. We present a 9-year-old girl with cystic fibrosis (CF) who presented with a 5-year history of nonprogressive hyperglycemia, demonstrated by abnormal oral glucose tolerance tests, glycated hemoglobin A1c (HbA1c) levels consistently >6.5%, and negative pancreatic autoantibodies. Subsequent genetic testing revealed a pathogenic heterozygous recessive mutation in the GCK gene at c.667G>A (p.Gly223Ser), consistent with a diagnosis of GCK-MODY. Significant dysglycemia in young children with CF should raise suspicion for alternative etiologies of diabetes and warrants further investigation. The clinical impact of underlying monogenic diabetes in patients with CF is unclear, and close follow-up is warranted. This case also offers unique insight on the impact of hyperglycemia in the absence of insulin deficiency on CF-specific outcomes.

Diagnosis of hepatic nuclear factor 1A monogenic diabetes mellitus (HNF1A-MODY) impacts antihyperglycemic treatment

Monogenic mutations of the hepatocyte nuclear factor 1 homeobox A maturity onset diabetes of the young (HNF1A-MODY) is characterized by early onset, typically before the age of 25 years. Patients are often not clinically recognized; however, the identification of HNF1A-MODY patients is crucial because they require different antihyperglycemic medical treatment than patients with type 1 or type 2 diabetes mellitus. We describe two adult patients with monogenic diabetes, both identified as HNF1A-MODY, genetically c.815G>A, p.Arg272His and c675delC, p.Ser225Argfs*8, respectively. They were misdiagnosed as having type 1 diabetes mellitus, and consequently, initiating insulin therapy led to hypoglycemia and unstable blood glucose control. Usually, sulfonylureas represent the basis of antidiabetic treatment in patients with HNF1A-MODY; however, all medical personnel involved in diabetes care should be aware of monogenic diabetes mellitus and the possibilities for genetic testing. The patients observed have shown the necessity of the identification and appropriate genetic diagnosis of HNF1A-MODY in order to discontinue insulin therapy and to initiate adjusted diabetes management.

The epidemiology, molecular pathogenesis, diagnosis, and treatment of maturity-onset diabetes of the young (MODY)

Background

The most common type of monogenic diabetes is maturity-onset diabetes of the young (MODY), a clinically and genetically heterogeneous group of endocrine disorders that affect 1–5% of all patients with diabetes mellitus. MODY is characterized by autosomal dominant inheritance but de novo mutations have been reported. Clinical features of MODY include young-onset hyperglycemia, evidence of residual pancreatic function, and lack of beta cell autoimmunity or insulin resistance. Glucose-lowering medications are the main treatment options for MODY. The growing recognition of the clinical and public health significance of MODY by clinicians, researchers, and governments may lead to improved screening and diagnostic practices. Consequently, this review article aims to discuss the epidemiology, pathogenesis, diagnosis, and treatment of MODY based on relevant literature published from 1975 to 2020.

Main body

The estimated prevalence of MODY from European cohorts is 1 per 10,000 in adults and 1 per 23,000 in children. Since little is known about the prevalence of MODY in African, Asian, South American, and Middle Eastern populations, further research in non-European cohorts is needed to help elucidate MODY’s exact prevalence. Currently, 14 distinct subtypes of MODY can be diagnosed through clinical assessment and genetic analysis. Various genetic mutations and disease mechanisms contribute to the pathogenesis of MODY. Management of MODY is subtype-specific and includes diet, oral antidiabetic drugs, or insulin.

Conclusions

Incidence and prevalence estimates for MODY are derived from epidemiologic studies of young people with diabetes who live in Europe, Australia, and North America. Mechanisms involved in the pathogenesis of MODY include defective transcriptional regulation, abnormal metabolic enzymes, protein misfolding, dysfunctional ion channels, or impaired signal transduction. Clinicians should understand the epidemiology and pathogenesis of MODY because such knowledge is crucial for accurate diagnosis, individualized patient management, and screening of family members.

A Computational Approach for Defining a Signature of β-Cell Golgi Stress in Diabetes

The Golgi apparatus (GA) is an important site of insulin processing and granule maturation, but whether GA organelle dysfunction and GA stress are present in the diabetic β-cell has not been tested. We used an informatics-based approach to develop a transcriptional signature of β-cell GA stress using existing RNA sequencing and microarray data sets generated using human islets from donors with diabetes and islets where type 1 (T1D) and type 2 (T2D) diabetes had been modeled ex vivo. To narrow our results to GA-specific genes, we applied a filter set of 1,030 genes accepted as GA associated. In parallel, we generated an RNA-sequencing data set from human islets treated with brefeldin A (BFA), a known GA stress inducer. Overlapping the T1D and T2D groups with the BFA data set, we identified 120 and 204 differentially expressed genes, respectively. In both the T1D and T2D models, pathway analyses revealed that the top pathways were associated with GA integrity, organization, and trafficking. Quantitative RT-PCR was used to validate a common signature of GA stress that included ATF3, ARF4, CREB3, and COG6 Taken together, these data indicate that GA-associated genes are dysregulated in diabetes and identify putative markers of β-cell GA stress.

The challenges of diagnosing diabetes in childhood

Diabetes is one of the most prevalent diseases worldwide, whereby type 1 diabetes mellitus (T1DM) alone involves nearly 15 million patients. Although T1DM and type 2 diabetes mellitus (T2DM) are the most common types, there are other forms of diabetes which may remain often under-diagnosed, or that can be misdiagnosed as being T1DM or T2DM. After an initial diagnostic step, the differential diagnosis among T1DM, T2DM, Maturity-Onset Diabetes of the Young (MODY) and others forms has important implication for both therapeutic and behavioral decisions. Although the criteria used for diagnosing diabetes mellitus are well defined by the guidelines of the American Diabetes Association (ADA), no clear indications are provided on the optimal approach to be followed for classifying diabetes, especially in children. In this circumstance, both routine and genetic blood test may play a pivotal role. Therefore, the purpose of this article is to provide, through a narrative literature review, some elements that may aid accurate diagnosis and classification of diabetes in children and young people.

Detection and analysis of glucose metabolism-related genes in childhood diabetes using targeted next-generation sequencing: In pediatric population-a hospital-based study

The aim of the present study was to explore the genetic causes of antibody-negative diabetes and investigate its characteristics. A total of 64 patients with new-onset diabetes (>6 m, <16 y) were identified and their initial clinical characteristics were analyzed. Of which, 32 cases with autoantibody-negative diabetes (male, 16 cases; female, 16 cases) were screened for auto-antibodies, including islet cell antibody, glutamic acid decarboxylase antibody and islet antigen-2, which were negative, and fasting C-peptide was ≥0.3 ng/ml. Peripheral blood DNA was extracted from the subjects and their parents for high-throughput sequencing of glucose metabolism-related genes. The group with the pathogenic variation was used as the experimental group. The control group comprised 32 cases of type 1 diabetes (T1D). Their baseline clinical characteristics were determined and statistically analyzed. Out of the 32 antibody-negative diabetes cases, 21 had possible related mutations. There were 2 HNF1B missense mutations, 1 GCK missense mutation and 1 de novo KCNJ11 missense mutation. GCGR c.118G>A p.G40S was present in patients with type 2 DM (T2DM); the locus is associated with T2DM susceptibility in China. An LIPC frameshift mutation was identified, which had not been previously reported; the gene was found to markedly affect protein function and be associated with glucose and lipid metabolism. It was concluded that children with antibody-negative T1D have monogenic diabetes. The present findings shed light on the etiology and mechanism of antibody-negative diabetes, which will enable the comprehensive analysis of antibody-negative diabetes genotypes and phenotypes and further help improved precision treatment.

Molecular and genetic regulation of pig pancreatic islet cell development

Reliance on rodents for understanding pancreatic genetics, development and islet function could limit progress in developing interventions for human diseases such as diabetes mellitus. Similarities of pancreas morphology and function suggest that porcine and human pancreas developmental biology may have useful homologies. However, little is known about pig pancreas development. To fill this knowledge gap, we investigated fetal and neonatal pig pancreas at multiple, crucial developmental stages using modern experimental approaches. Purification of islet β-, α- and δ-cells followed by transcriptome analysis (RNA-seq) and immunohistology identified cell- and stage-specific regulation, and revealed that pig and human islet cells share characteristic features that are not observed in mice. Morphometric analysis also revealed endocrine cell allocation and architectural similarities between pig and human islets. Our analysis unveiled scores of signaling pathways linked to native islet β-cell functional maturation, including evidence of fetal α-cell GLP-1 production and signaling to β-cells. Thus, the findings and resources detailed here show how pig pancreatic islet studies complement other systems for understanding the developmental programs that generate functional islet cells, and that are relevant to human pancreatic diseases.

Inadequate β-cell mass is essential for the pathogenesis of type 2 diabetes

For patients with type 1 diabetes, it is accepted among the scientific community that there is a marked reduction in β-cell mass; however, with type 2 diabetes, there is disagreement as to whether this reduction in mass occurs in every case. Some have argued that β-cell mass in some patients with type 2 diabetes is normal and that the cause of the hyperglycaemia in these patients is a functional abnormality of insulin secretion. In this Personal View, we argue that a deficient β-cell mass is essential for the development of type 2 diabetes. The main point is that there are enormous (≥10 fold) variations in insulin sensitivity and insulin secretion in the general population, with a very close correlation between these two factors for any individual. Although β-cell mass cannot be accurately measured in living patients, it is highly likely that it too is highly correlated with insulin sensitivity and secretion. Thus, our argument is that a person with type 2 diabetes can have a β-cell mass that is the same as a person without type 2 diabetes, but because they are insulin resistant, the mass is inadequate and responsible for their diabetes. Because the abnormal insulin secretion of diabetes is caused by dysglycaemia and can be largely reversed with glycaemic control, it is a less serious problem than the reduction in β-cell mass, which is far more difficult to restore.

Next generation sequencing targeted gene panel in Greek MODY patients increases diagnostic accuracy

BACKGROUND

Maturity Onset Diabetes of the Young (MODY) constitutes a genetically and clinically heterogeneous type of monogenic diabetes. It is characterized by early onset, autosomal dominant inheritance and a defect in pancreatic β-cell insulin secretion. To date, various MODY subtypes have been reported, each one of a distinct genetic etiology.

OBJECTIVE

The aim of this study was to identify the molecular defects of 50 patients with MODY employing the methodology of next generation sequencing (NGS) targeted gene panel.

METHODS

A panel of seven MODY genes was designed and employed to screen 50 patients fulfilling the MODY diagnostic criteria. Patients with no pathogenic, likely pathogenic or uncertain significance variants detected, were further tested by multiplex ligation-dependent probe amplification (MLPA) for copy number variations (CNVs).

RESULTS

Eight different pathogenic or likely pathogenic variants were identified in eight MODY patients (diagnostic rate 16%). Five variants of uncertain significance were also detected in seven MODY patients. Five novel pathogenic and likely pathogenic variants were detected in the genes GCK; p.Cys371X, HNF1A; p.Asn402Tyr, HNF4A; p.Glu285Lys, and ABCC8; p.Met1514Thr and p.Ser1386Phe. Two de novo heterozygous deletions of the entire HNF1B gene were detected in two patients, raising the diagnostic rate to 20%.

CONCLUSIONS

Although many MODY patients still remain without exact MODY type identification, the application of NGS methodology provided rapid results, increased diagnostic accuracy, and was cost-effective compared to Sanger sequencing. Accurate genetic diagnosis of the MODY subtype is important for treatment selection, disease prognosis, and family counseling.

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

BACKGROUND

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

MAIN BODY

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

CONCLUSIONS

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

Targeted sequencing identifies novel variants in common and rare MODY genes

BACKGROUND

Maturity-onset diabetes of the young (MODY) is a form of monogenic diabetes with autosomal dominant inheritance. To date, mutations in 11 genes have been frequently associated with this phenotype. In Brazil, few cohorts have been screened for MODY, all using a candidate gene approach, with a high prevalence of undiagnosed cases (MODY-X).

METHODS

We conducted a next-generation sequencing target panel (tNGS) study to investigate, for the first time, a Brazilian cohort of MODY patients with a negative prior genetic analysis. One hundred and two patients were selected, of which 26 had an initial clinical suspicion of MODY-GCK and 76 were non-GCK MODY.

RESULTS

After excluding all benign and likely benign variants and variants of uncertain significance, we were able to assign a genetic cause for 12.7% (13/102) of the probands. Three rare MODY subtypes were identified (PDX1/NEUROD1/ABCC8), and eight variants had not been previously described/mapped in genomic databases. Important clinical findings were evidenced in some cases after genetic diagnosis, such as MODY-PDX1/HNF1B.

CONCLUSION

A multiloci genetic approach allowed the identification of rare MODY subtypes, reducing the large percentage of MODY-X in Brazilian cases and contributing to a better clinical, therapeutic, and prognostic characterization of these rare phenotypes.

First Report of Diabetes Phenotype due to a Loss-of-Function ABCC8 Mutation Previously Known to Cause Congenital Hyperinsulinism

Monogenic Diabetes is relatively rare, representing only 1-2% of total diabetes cases; nevertheless, it is often misdiagnosed primarily as type 1 diabetes, leading to unnecessary insulin therapy and delayed recognition of affected family members. In the present article, we describe a case of a young, male patient who presented with hyperglycemia in the absence of ketosis and following genetic testing; he proved to harbor the loss-of-function p.Arg1353His (c.4058G>A) mutation in the ABCC8 gene, inherited from his mother. This mutation has been previously described in patients with Congenital Hyperinsulinism. Furthermore, different mutations in the ABCC8 gene have been linked with MODY 12, type 2, and gestational diabetes; however, to the best of our knowledge, this is the first report that associates this specific mutation with diabetes phenotype. ABCC8-related diabetes is characterized by remarkable heterogeneity in terms of clinical presentation and therapeutic approach. Early diagnosis and individualized treatment are essential to achieving metabolic targets and avoiding long-term diabetes complications.