Can obesity exacerbate hyperinsulinaemia in the presence of the mutation of an insulin receptor gene?

Insulin receptor gene (INSR) mutations are a relatively rare and diverse cause of insulin resistance (IR), typically associated with a lean phenotype. However, we present a unique case of severe obesity and Type A severe IR syndrome in a patient with a heterozygous mutation of the INSR gene. Next Generation Sequencing (NGS) analysis was conducted to identify the genetic variant. A 16-year-old girl with severe obesity (BMI-SDS +2.79) exhibited markedly elevated basal insulin levels (>800 mcU/L). Despite obesity being a known cause of hyperinsulinism, further investigation was pursued due to the severity of hyperinsulinaemia. A heterozygous nucleotide variant at the donor splicing site of intron 13 (c.2682 + 1G > A) of the INSR gene was identified. This mutation was also present in the proband's normal-weight mother and her two younger brothers with obesity. Metformin treatment provided limited benefits, but subsequent liraglutide therapy resulted in weight loss and decreased IR 3 months after initiation. Our findings suggest that obesity can exacerbate hyperinsulinaemia in individuals with an INSR gene mutation. Although INSR signalling defects play a minor role in the aetiology of IR, they should still be considered in the diagnostic pathway, particularly in severe phenotypes. Clinicians should not overlook the possibility of genetic causes in patients with obesity and IR, as they may require personalized management approaches.

The Pathogenic Diagnosis in Pediatric Diabetology: Next Generation Sequencing and Precision Therapy.

In pediatric diabetology, a precise diagnosis is very important because it allows early and correct clinical management of the patient. Monogenic diabetes (MD), which accounts for 1-6% of all pediatric-adolescent diabetes cases, is the most relevant example of precision medicine. The definitive diagnosis of MD, possible only by genetic testing, allows us to direct patients to more appropriate therapy in relation to the identified mutation. In some cases, MD patients can avoid insulin and be treated with oral hypoglycemic drugs with a perceptible impact on both the quality of life and the healthcare costs. However, the genetic and phenotypic heterogeneity of MD and the overlapping clinical characteristics between different forms, can complicate the diagnostic process. In recent years, the development of Next-Generation Sequencing (NGS) methodology, which allows the simultaneous analysis of multiple genes, has revolutionized molecular diagnostics, becoming the cornerstone of MD precision diagnosis. We report two cases of patients with clinical suspects of MD in which a genetic test was carried out, using a NGS multigenic panel, and it clarified the correct pathogenesis of diabetes, allowing us to better manage the disease both in probands and other affected family members.

Metabolic Treatment of Wolfram Syndrome.

Wolfram Syndrome (WS) is a very rare genetic disorder characterized by several symptoms that occur from childhood to adulthood. Usually, the first clinical sign is non-autoimmune diabetes even if other clinical features (optic subatrophy, neurosensorial deafness, diabetes insipidus) may be present in an early state and may be diagnosed after diabetes' onset. Prognosis is poor, and the death occurs at the median age of 39 years as a consequence of progressive respiratory impairment, secondary to brain atrophy and neurological failure. The aim of this paper is the description of the metabolic treatment of the WS. We reported the experience of long treatment in patients with this syndrome diagnosed in pediatric age and followed also in adult age. It is known that there is a correlation between metabolic control of diabetes, the onset of other associated symptoms, and the progression of the neurodegenerative alterations. Therefore, a multidisciplinary approach is necessary in order to prevent, treat and carefully monitor all the comorbidities that may occur. An extensive understanding of WS from pathophysiology to novel possible therapy is fundamental and further studies are needed to better manage this devastating disease and to guarantee to patients a better quality of life and a longer life expectancy.

NGS Analysis Revealed Digenic Heterozygous GCK and HNF1A Variants in a Child with Mild Hyperglycemia: A Case Report.

Monogenic diabetes (MD) represents a heterogeneous group of disorders whose most frequent form is maturity-onset diabetes of the young (MODY). MD is predominantly caused by a mutation in a single gene. We report a case of a female patient with suspected MD and a positive family history for diabetes and obesity. In this patient, two gene variants have been identified by next-generation sequencing (NGS): one in the Glucokinase (GCK) gene reported in the Human Gene Mutation Database (HGMD) and in the literature associated with GCK/MODY, and the other in the hepatocyte nuclear factor 1A (HNF1A) gene not previously described. The GCK variant was also identified in the hyperglycemic father, whereas the HNF1A variant was present in the mother. This new case of digenic GCK/HNF1A variants identified in a hyperglycemic subject, evidences the importance of NGS analysis in patients with suspected MD. In fact, this methodology will allow us to both increase the number of diagnoses and to identify mutations in more than one gene, with a better understanding of the genetic cause, and the clinical course, of the disease.

Cystic Fibrosis-Related Diabetes (CFRD): Overview of Associated Genetic Factors.

Cystic fibrosis (CF) is the most common autosomal recessive disease in the Caucasian population and is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene that encodes for a chloride/bicarbonate channel expressed on the membrane of epithelial cells of the airways and of the intestine, as well as in cells with exocrine and endocrine functions. A common nonpulmonary complication of CF is cystic fibrosis-related diabetes (CFRD), a distinct form of diabetes due to insulin insufficiency or malfunction secondary to destruction/derangement of pancreatic betacells, as well as to other factors that affect their function. The prevalence of CFRD increases with age, and 40-50% of CF adults develop the disease. Several proposed hypotheses on how CFRD develops have emerged, including exocrine-driven fibrosis and destruction of the entire pancreas, as well as contrasting theories on the direct or indirect impact of CFTR mutation on islet function. Among contributors to the development of CFRD, in addition to CFTR genotype, there are other genetic factors related and not related to type 2 diabetes. This review presents an overview of the current understanding on genetic factors associated with glucose metabolism abnormalities in CF.

A Real-World Experience of Clinical, Biochemical and Genetic Assessment of Patients with Homozygous Familial Hypercholesterolemia.

Homozygous familial hypercholesterolemia (HoFH), the severest form of familial hypercholesterolemia (FH), is characterized by very high LDL-cholesterol levels and a high frequency of coronary heart disease. The disease is caused by the presence of either a pathogenic variant at homozygous status or of two pathogenic variants at compound heterozygous status in the LDLR, APOB, PCSK9 genes. We retrospectively analyzed data of 23 HoFH patients (four children and 19 adults) identified during the genetic screening of 724 FH patients. Genetic screening was performed by sequencing FH causative genes and identifying large rearrangements of LDLR. Among the HoFH patients, four out of 23 (17.4%) were true homozygotes, whereas 19 out of 23 (82.6%) were compound heterozygotes for variants in the LDLR gene. Basal LDL-cholesterol was 12.9 ± 2.9 mmol/L. LDL-cholesterol levels decreased to 7.2 ± 1.8 mmol/L when treated with statin/ezetimibe and to 5.1 ± 3.1 mmol/L with anti-PCSK9 antibodies. Homozygous patients showed higher basal LDL-cholesterol and a poorer response to therapy compared with compound heterozygotes. Since 19 unrelated patients were identified in the Campania region (6,000,000 inhabitants) in southern Italy, the regional prevalence of HoFH was estimated to be at least 1:320,000. In conclusion, our results revealed a worse phenotype for homozygotes compared with compound heterozygotes, thereby highlighting the role of genetic screening in differentiating one genetic status from the other.