Syndromic forms of congenital hyperinsulinism

Large copy number variants are an important cause of congenital hyperinsulinism that should be screened for during routine testing

Introduction

Congenital hyperinsulinism (HI) is characterized by inappropriate insulin secretion from the pancreatic beta-cells which causes severe hypoglycemia. Copy number variants (CNVs) encompassing multiple genes (contiguous gene CNVs) can cause syndromic forms of HI although they are not typically screened for during routine genetic testing for this condition. We aimed to assess the prevalence of disease-causing contiguous gene CNVs in a cohort of individuals referred for HI genetic testing.

Methods

Our cohort consisted of 3,763 individuals, of which 1,916 had received a genetic diagnosis for their HI and 1,847 were genetically unsolved following routine testing. We screened for 6 different contiguous gene CNVs using next-generation sequencing data from all individuals in the genetically unsolved cohort and searched for patients in our solved cohort who had already been found to have one of these CNVs.

Results

We identified a contiguous gene CNV affecting 5 of the 6 genomic loci in 53 probands; 28 from the solved cohort and 25 from the genetically unsolved cohort. Variants on the X chromosome were most common, being detected in 24/53 children. Overall, these variants represented 2.7% (53/1,941) of genetic diagnoses, which is similar to the prevalence of variants in other commonly screened HI genes.

Discussion

These results confirm that contiguous gene CNVs are an important cause of HI which should be included in standard gene panel testing processes as this will improve pick-up rates for genetic diagnoses in HI.

Non-surgical Treatment May be Appropriate for Most Chinese Children With Monogenic Congenital Hyperinsulinism Based on a Retrospective Study of 121 Patients

Objective: There is a notable absence of extensive Chinese studies involving monogenic congenital hyperinsulinism (CHI). The purpose of this large retrospective Chinese cohort with monogenic CHI from a national children's medical center was to analyze the genetic and clinical characteristics. Methods: We compared clinical characteristics grouped by genotypes based on CHI-targeted next-generation sequencing (tNGS) and performed subgroup analyses by onset time. Results: Totally, 121 non-consanguineous patients were enrolled. Among them, 79 patients (65.3%) had variants in ATP-sensitive potassium channel (KATP) genes (62 heterozygotes and 17 compound heterozygotes), 35 (28.9%) in glutamate dehydrogenase 1 (GLUD1), and 7 (5.8%) in rare genes (hydroxyacyl-CoA dehydrogenase [HADH], glucokinase [GCK], and hepatocyte nuclear factor 4 alpha [HNF4A]). Ten patients had ATP binding cassette subfamily C member 8 (ABCC8) variants (p.G111R), and 12 had GLUD1 variants (p.S498L), suggesting two potential founder variants. Three ABCC8 variants (p.G1478R, p.L580_S581insFASL, and p.S986⁣ ∗ ) and two HNF4A variants (p.R63W and p.V382I) were previously reported to be associated with diabetes. Non-surgical treatment was effective in 65.9% of patients with KATP variants, while in 100% of those with non-KATP variants. For the subgroup of KATP variants, neonatal-onset patients tended to present with mild symptoms (67.9% versus 19.3%), had a higher proportion of surgical intervention (24.5% versus 3.8%), and displayed higher levels of serum insulin and C-peptide than non-neonatal onset ones (p < 0.001). Conclusion: The absence of homozygous variants in KATP genes and a quite higher proportion of GLUD1 variants than previous cohorts, may explain a high response rate of non-surgical treatment in this study. Surgery might be considered for neonatal-onset children, especially when KATP variants were discovered but not for those carried variants reported to cause diabetes in later life. While expanding the genotypic spectrum, we also highlight the clinical significance of genetic screening.

Clinical and genetic characteristics of a child with Sotos syndrome and attention-deficit/hyperactivity disorder: A case report

BACKGROUND

Sotos syndrome is an autosomal dominant disorder, whereas attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition. This report aimed to summarize the clinical and genetic features of a pediatric case of Soros syndrome and ADHD in a child exhibiting precocious puberty.

CASE SUMMARY

The patient presented with accelerated growth and advanced skeletal maturation; however, she lacked any distinct facial characteristics related to specific genetic disorders. Genetic analyses revealed a paternally inherited heterozygous synonymous mutation [c.4605C>T (p.Arg1535Arg)]. Functional analyses suggested that this mutation may disrupt splicing, and bioinformatics analyses predicted that this mutation was likely pathogenic. After an initial diagnosis of Sotos syndrome, the patient was diagnosed with ADHD during the follow-up period at the age of 8 years and 7 months.

CONCLUSION

The potential for comorbid ADHD in Sotos syndrome patients should be considered to avoid the risk of a missed diagnosis.

Etiology of the Neonatal Hypoglycemias

To provide a more appropriate foundation for dealing with the problem of hypoglycemia in newborn infants, this article focuses on the mechanisms which underlie the various forms of neonatal hypoglycemia and discusses their implications for newborn care. Evidence indicates that all of the major forms of neonatal hypoglycemia are the result of hyperinsulinism due to dysregulation of pancreatic islet insulin secretion. Based on these observations, the authors propose that routine measurement of B-hydroxybutyrate should be considered an essential part of glucose monitoring in newborn infants.

Trisomy 13 with unusual histological features typically described in Beckwith-Wiedemann Spectrum

Trisomy 13, known as Patau syndrome, is a common aneuploidy with a well-known clinical phenotype. This case report describes a trisomy 13 patient with unusual autopsy findings, including features resembling the Beckwith-Wiedemann Spectrum. Due to abnormalities of gestational ultrasounds, a prenatal karyotype of amniotic fluid cells was performed, which resulted in 47, XY+13. Autopsy microscopy studies identified leptomeningeal glioneuronal heterotopia, which was not described as belonging to Patau syndrome. Other atypical findings were diffuse hyperplasia of pancreatic islets of Langerhans and adrenals enlargement with marked adrenocortical cytomegaly, characteristically seen in the Beckwith-Wiedemann Spectrum. Molecular genetic tests were not performed for the Beckwith-Wiedemann Spectrum. Still, due to the rarity of both disorders, this report may support the evidence that trisomy 13 can affect tissue organization and lead to unusual histopathologic features resembling classic overgrowth disorders.

Congenital Hyperinsulinism in Humans and Insulin Secretory Dysfunction in Mice Caused by Biallelic DNAJC3 Variants

The BiP co-chaperone DNAJC3 protects cells during ER stress. In mice, the deficiency of DNAJC3 leads to beta-cell apoptosis and the gradual onset of hyperglycemia. In humans, biallelic DNAJC3 variants cause a multisystem disease, including early-onset diabetes mellitus. Recently, hyperinsulinemic hypoglycemia (HH) has been recognized as part of this syndrome. This report presents a case study of an individual with HH caused by DNAJC3 variants and provides an overview of the metabolic phenotype of individuals with HH and DNAJC3 variants. The study demonstrates that HH may be a primary symptom of DNAJC3 deficiency and can persist until adolescence. Additionally, glycemia and insulin release were analyzed in young DNACJ3 knockout (K.O.) mice, which are equivalent to human infants. In the youngest experimentally accessible age group of 4-week-old mice, the in vivo glycemic phenotype was already dominated by a reduced total insulin secretion capacity. However, on a cellular level, the degree of insulin release of DNAJC3 K.O. islets was higher during periods of increased synthetic activity (high-glucose stimulation). We propose that calcium leakage from the ER into the cytosol, due to disrupted DNAJC3-controlled gating of the Sec61 channel, is the most likely mechanism for HH. This is the first genetic mechanism explaining HH solely by the disruption of intracellular calcium homeostasis. Clinicians should screen for HH in DNAJC3 deficiency and consider DNAJC3 variants in the differential diagnosis of congenital hyperinsulinism.

Overgrowth syndromes, diagnosis and management

PURPOSE OF REVIEW

This review will focus on the current knowledge of the diagnosis and management of overgrowth syndromes with specific focus on mosaic conditions and treatment strategies.

RECENT FINDINGS

With the implementation of massively parallel sequencing, the genetic etiology of many classically described overgrowth syndromes have been identified. More recently, the role of mosaic genetic changes has been well described in numerous syndromes. Furthermore, the role of imprinting and methylation, especially of the 11p15 region, has been shown to be instrumental for growth. Perhaps most importantly, many overgrowth syndromes carry an increased risk of neoplasm formation especially in the first 10 years of life and possibly beyond. The systematic approach to the child with overgrowth will aide in timely diagnosis and efficiently align them with appropriate screening strategies. In some cases, precision medical interventions are available to target the perturbed growth signaling pathways.

SUMMARY

The systematic approach to the child with overgrowth aids in the standardization of the diagnostic pathway for these young patients, thereby expediting the diagnostic timeline, enabling rigorous monitoring, and delivering tailored therapeutic interventions.

Evaluation and management of neonatal onset hyperinsulinemic hypoglycemia: a single neonatal center experience

OBJECTIVES

To evaluate the clinical characteristics and treatment options of neonates requiring prolonged hospitalization due to persistent hyperinsulinemic hypoglycemia (HH).

METHODS

This retrospective cohort study included infants >34 weeks of gestation at birth who were born in our hospital between 2018 and 2021, diagnosed with HH, and required diazoxide within the first 28 days of life. The baseline clinical characteristics, age at the time of diagnosis and treatment options in diazoxide resistance cases were recorded. Genetic mutation analysis, if performed, was also included.

RESULTS

A total of 32 infants diagnosed with neonatal HH were followed up. Among the cohort, 25 infants were classified as having transient form of HH and seven infants were classified as having congenital hyperinsulinemic hypoglycemia (CHI). Thirty-one percent of the infants had no risk factors. The median birth weight was significantly higher in the CHI group, whereas no differences were found in other baseline characteristics. Patients diagnosed with CHI required higher glucose infusion rate, higher doses, and longer duration of diazoxide treatment than those in the transient HH group. Eight patients were resistant to diazoxide, and six of them required treatment with octreotide and finally sirolimus. Sirolimus prevented the need of pancreatectomy in five of six patients without causing major side effects. Homozygous mutations in the ABCC8 gene were found in four patients with CHI.

CONCLUSIONS

The risk of persistent neonatal hyperinsulinism should be considered in hypoglycemic neonates particularly located in regions with high rates of consanguinity. Our study demonstrated sirolimus as an effective treatment option in avoiding pancreatectomy in severe cases.

Hypoglycemia in Children: Major Endocrine-Metabolic Causes and Novel Therapeutic Perspectives

Hypoglycemia is due to defects in the metabolic systems involved in the transition from the fed to the fasting state or in the hormone control of these systems. In children, hypoglycemia is considered a metabolic-endocrine emergency, because it may lead to brain injury, permanent neurological sequelae and, in rare cases, death. Symptoms are nonspecific, particularly in infants and young children. Diagnosis is based on laboratory investigations during a hypoglycemic event, but it may also require biochemical tests between episodes, dynamic endocrine tests and molecular genetics. This narrative review presents the age-related definitions of hypoglycemia, its pathophysiology and main causes, and discusses the current diagnostic and modern therapeutic approaches.