# Congenital Hyperinsulinemic Hypoglycemia With a New HADH Mutation and Pancreatic Overexpression of GLP-1 Receptors

## TL;DR

A new mutation in the HADH gene causes congenital hyperinsulinemic hypoglycemia, with long-term management involving diazoxide and somatostatin analogues.

## Contribution

A novel homozygous HADH gene mutation is identified in two related CHH patients, along with pancreatic overexpression of GLP-1 receptors.

## Key findings

- A new HADH gene variant (c.796G > T) was found in two patients with CHH.
- 68Ga-DOTA exendin imaging showed increased GLP-1 receptor expression in the pancreas.
- Diazoxide and somatostatin analogues were effective in managing hypoglycemic episodes.

## Abstract

The most common cause of endogenous hyperinsulinemic hypoglycemia in neonates [congenital hyperinsulinemic hypoglycemia (CHH)] is different monogenic forms of gene mutations. About 50% of the mutations are known. We present a new mutation within the short-chain L-3-hydroxyacyl-CoA dehydrogenase (HADH) gene causing CHH in 2 related patients.

The course of 2 consanguineous patients with CHH are presented with a follow-up of >30 years. NextSeq 500 sequencing was performed and confined on known genes with autosomal recessive inheritance, namely ABCC8 (MANE Select: NM_00352.6), HADH (MANE Select: NM_005327.7), and KCNJ11 (MANE Select: NM_00525.4). Acylcarnitine profiles were measured and 68Ga-DOTA exendin positron emission tomography/computer tomography was performed.

CHH was diagnosed in both patients in the neonatal period. A therapy with diazoxid was initiated, which initially stabilized the disease in both children. With advancing age, more hypoglycemic events occurred with an increase in carbohydrate intake, leading to obesity in both patients. In addition to diazoxide, somatostatin analogues were successfully added in adulthood. A genetic analysis documented a new homozygote mutation in the HADH gene (HADH-variant c.796G > T). An acylcarnitine profile showed an increased plasma butyryl-carnitine, consistent with a dysfunction of the HADH enzyme. 68Gallium-DOTA-exendin showed an increased uptake in the whole pancreas in both patients.

Clinical presentation, biochemical workup, and therapeutical response to diazoxide and somatostatin analogues are consistent with previous reports of HADH mutations. The overexpression of glucagon-like peptide 1 receptors in this context warrants further research.