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

Monogenic diabetes

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

Pediatric diabetes in China: Challenges and actions

Pediatric diabetes is growing in China. The annual incidence of childhood type 1 diabetes is about 2.02-5.3 per 100,000 person-years. Type 2 diabetes in children and adolescents is increasing dramatically with the high-speed urbanization of China. The prevalence of type 2 diabetes varies from 1.64/100, 000 to 15.16/100,000 based on the geography and economy. Monogenic diabetes used to be underestimated in China and now more cases are emerging. In this review, we give an overview of pediatric diabetes in China, present the progresses and challenges in management of pediatric diabetes, and discuss the government policy and potential actions in China, for better life quality of diabetic families.

Role of Actionable Genes in Pursuing a True Approach of Precision Medicine in Monogenic Diabetes

Monogenic diabetes is a genetic disorder caused by one or more variations in a single gene. It encompasses a broad spectrum of heterogeneous conditions, including neonatal diabetes, maturity onset diabetes of the young (MODY) and syndromic diabetes, affecting 1-5% of patients with diabetes. Some of these variants are harbored by genes whose altered function can be tackled by specific actions ("actionable genes"). In suspected patients, molecular diagnosis allows the implementation of effective approaches of precision medicine so as to allow individual interventions aimed to prevent, mitigate or delay clinical outcomes. This review will almost exclusively concentrate on the clinical strategy that can be specifically pursued in carriers of mutations in "actionable genes", including ABCC8, KCNJ11, GCK, HNF1A, HNF4A, HNF1B, PPARG, GATA4 and GATA6. For each of them we will provide a short background on what is known about gene function and dysfunction. Then, we will discuss how the identification of their mutations in individuals with this form of diabetes, can be used in daily clinical practice to implement specific monitoring and treatments. We hope this article will help clinical diabetologists carefully consider who of their patients deserves timely genetic testing for monogenic diabetes.

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.

Multifactorial Basis and Therapeutic Strategies in Metabolism-Related Diseases

Throughout the 20th and 21st centuries, the incidence of non-communicable diseases (NCDs), also known as chronic diseases, has been increasing worldwide. Changes in dietary and physical activity patterns, along with genetic conditions, are the main factors that modulate the metabolism of individuals, leading to the development of NCDs. Obesity, diabetes, metabolic associated fatty liver disease (MAFLD), and cardiovascular diseases (CVDs) are classified in this group of chronic diseases. Therefore, understanding the underlying molecular mechanisms of these diseases leads us to develop more accurate and effective treatments to reduce or mitigate their prevalence in the population. Given the global relevance of NCDs and ongoing research progress, this article reviews the current understanding about NCDs and their related risk factors, with a focus on obesity, diabetes, MAFLD, and CVDs, summarizing the knowledge about their pathophysiology and highlighting the currently available and emerging therapeutic strategies, especially pharmacological interventions. All of these diseases play an important role in the contamination by the SARS-CoV-2 virus, as well as in the progression and severity of the symptoms of the coronavirus disease 2019 (COVID-19). Therefore, we briefly explore the relationship between NCDs and COVID-19.

Generation of β Cells from iPSC of a MODY8 Patient with a Novel Mutation in the Carboxyl Ester Lipase (CEL) Gene

CONTEXT

Maturity-onset diabetes of the young (MODY) 8 is a rare form of monogenic diabetes characterized by a mutation in CEL (carboxyl ester lipase) gene, which leads to exocrine pancreas dysfunction, followed by β cell failure. Induced pluripotent stem cells can differentiate into functional β cells. Thus, β cells from MODY8 patients can be generated in vitro and used for disease modelling and cell replacement therapy.

METHODS

A genetic study was performed in a patient suspected of monogenic diabetes.

RESULTS

A novel heterozygous pathogenic variant in CEL (c.1818delC) was identified in the proband, allowing diagnosis of MODY8. Three MODY8-iPSC (induced pluripotent stem cell) clones were reprogrammed from skin fibroblasts of the patient, and their pluripotency and genomic stability confirmed. All 3 MODY8-iPSC differentiated into β cells following developmental stages. MODY8-iPSC-derived β cells were able to secrete insulin upon glucose dynamic perifusion. The CEL gene was not expressed in iPSCs nor during any steps of endocrine differentiation.

CONCLUSION

iPSC lines from a MODY8 patient with a novel pathogenic variant in the CEL gene were generated; they are capable of differentiation into endocrine cells, and β cell function is preserved in mutated cells. These results set the basis for in vitro modelling of the disease and potentially for autologous β cell replacement.

Tunisian Maturity-Onset Diabetes of the Young: A Short Review and a New Molecular and Clinical Investigation

INTRODUCTION/AIMS

Maturity-Onset Diabetes of the Young (MODY) is a monogenic non-autoimmune diabetes with 14 different genetic forms. MODY-related mutations are rarely found in the Tunisian population. Here, we explored MODY related genes sequences among seventeen unrelated Tunisian probands qualifying the MODY clinical criteria.

MATERIALS AND METHODS

The GCK and HNF1A genes were systematically analyzed by direct sequencing in all probands. Then, clinical exome sequencing of 4,813 genes was performed on three unrelated patients. Among them, 130 genes have been reported to be involved in the regulation of glucose metabolism, β-cell development, differentiation and function. All identified variants were analyzed according to their frequencies in the GnomAD database and validated by direct sequencing.

RESULTS

We identified the previously reported GCK mutation (rs1085307455) in one patient. The clinical features of the MODY2 proband were similar to previous reports. In this study, we revealed rare and novel alterations in GCK (rs780806456) and ABCC8 (rs201499958) genes with uncertain significance. We also found two likely benign alterations in HNF1A (rs1800574) and KLF11 (rs35927125) genes with minor allele frequencies similar to those depicted in public databases. No pathogenic variants have been identified through clinical exome analysis.

CONCLUSIONS

The most appropriate patients were selected, following a strict clinical screening approach, for genetic testing. However, the known MODY1-13 genes could not explain most of the Tunisian MODY cases, suggesting the involvement of unidentified genes in the majority of Tunisian affected families.

Monogenic diabetes characteristics in a transnational multicenter study from Mediterranean countries

BACKGROUND

Diagnosis of monogenic diabetes has important clinical implications for treatment and health expenditure. However, its prevalence remains to be specified in many countries, particularly from South Europe, North Africa and Middle-East, where non-autoimmune diabetes in young adults is increasing dramatically.

AIMS

To identify cases of monogenic diabetes in young adults from Mediterranean countries and assess the specificities between countries.

METHODS

We conducted a transnational multicenter study based on exome sequencing in 204 unrelated patients with diabetes (age-at-diagnosis: 26.1 ± 9.1 years). Rare coding variants in 35 targeted genes were evaluated for pathogenicity. Data were analyzed using one-way ANOVA, chi-squared test and factor analysis of mixed data.

RESULTS

Forty pathogenic or likely pathogenic variants, 14 of which novel, were identified in 36 patients yielding a genetic diagnosis rate of 17.6%. The majority of cases were due to GCK, HNF1A, ABCC8 and HNF4A variants. We observed highly variable diagnosis rates according to countries, with association to genetic ancestry. Lower body mass index and HbA1c at study inclusion, and less frequent insulin treatment were hallmarks of pathogenic variant carriers. Treatment changes following genetic diagnosis have been made in several patients.

CONCLUSIONS

Our data from patients in several Mediterranean countries highlight a broad clinical and genetic spectrum of diabetes, showing the relevance of wide genetic testing for personalized care of early-onset diabetes.

Disentangling the heterogeneity of adulthood-onset non-autoimmune diabetes: a little closer but lot more to do

Diabetes diagnosed in adults is a highly heterogeneous disorder. It mostly consists of what is referred to as type 2 diabetes but also comprises other entities (i.e. different diseases), including latent autoimmune diabetes, late onset forms of monogenic diabetes and familial diabetes of the adulthood, which has recently been the source of new diabetogenes discovery. Notably, type 2 diabetes is itself heterogeneous as it includes subtypes with onset at the extremes of age and/or weight distributions characterized by different degree of hyperglycemia and cardiovascular risk as compared to common forms of type 2 diabetes occurring in middle-aged, overweight/obese individuals. Understanding whether these are different presentations of one, highly heterogeneous disease or separate nosological entities with different clinical trajectories and requiring different treatments is essential to effectively pursue the path of precision medicine.

Systematic Genetic Study of Youth With Diabetes in a Single Country Reveals the Prevalence of Diabetes Subtypes, Novel Candidate Genes, and Response to Precision Therapy

Identifying gene variants causing monogenic diabetes (MD) increases understanding of disease etiology and allows for implementation of precision therapy to improve metabolic control and quality of life. Here, we aimed to assess the prevalence of MD in youth with diabetes in Lithuania, uncover potential diabetes-related gene variants, and prospectively introduce precision treatment. First, we assessed all pediatric and most young-adult patients with diabetes in Lithuania (n = 1,209) for diabetes-related autoimmune antibodies. We then screened all antibody-negative patients (n = 153) using targeted high-throughput sequencing of >300 potential candidate genes. In this group, 40.7% had MD, with the highest percentage (100%) in infants (diagnosis at ages 0-12 months), followed by those diagnosed at ages >1-18 years (40.3%) and >18-25 years (22.2%). The overall prevalence of MD in youth with diabetes in Lithuania was 3.5% (1.9% for GCK diabetes, 0.7% for HNF1A, 0.2% for HNF4A and ABCC8, 0.3% for KCNJ11, and 0.1% for INS). Furthermore, we identified likely pathogenic variants in 11 additional genes. Microvascular complications were present in 26% of those with MD. Prospective treatment change was successful in >50% of eligible candidates, with C-peptide >252 pmol/L emerging as the best prognostic factor.

Pathology in the era of "Personalized Medicine": The need to learn how to integrate multivariate immunohistochemical and "omics" data with clinicopathologic information in a clinically relevant way"

"Personalized medicine" has been proposed as a new paradigm for patient care that, based on the integration of genomics and other "omics" data with clinical and other multidisciplinary information, promises early disease detection, improved outcomes and reduced side effects to therapies. Pathologists have become important participants in this new approach as the guardians of tissues and experts in the performance of molecular and other laboratory tests. Large amounts of new laboratory data in multiple neoplasms and other entities are being reported but there has been limited discussion about how best to evaluate the clinical significance of this information and how to integrate it into currently available diagnostic and therapeutic modalities. This article introduces a variety of epistemological problems presented by the "personalized medicine" paradigm and briefly discusses various topics that will be evaluated in further detail in future articles of this new series on Evidence-Based Pathology.