Congenital disorders of glucose metabolism in adults with nondiabetic hypoglycemia

Abstract

BACKGROUND: Recent clinical descriptions have shown that in adult patients, the cause of nondiabetic hypoglycemia (NDH) may be various genetically determined disorders of glucose metabolism or insulin synthesis/bioavailability. In this connection, in adult patients with NDH of unclear genesis, it is important to conduct a genetic study in order to search for mutations in genes associated with congenital disorders of glucose metabolism (CDGM).AIM: To evaluate the effectiveness of genetic testing to exclude CDGM in adult patients with idiopathic NDH.MATERIALS AND METHODS: Based on the analysis of the literature, a targeted panel has been developed, including 30 genes, mutations in which are associated with the following groups of diseases: 1) congenital hyperinsulinism (KCNJ11, ABCC8, GLUD1, HADH, UCP2, HNF4A, HNF1A, GCK, INSR, SLC16A1); 2) glycogen storage diseases (AGL); 3) other carbohydrate metabolism disorders (ALDOB, FBP1); 4) glycosylation defects (PMM2, ALG3, PGM1, MPI); 4) defects in fatty acid oxidation (ACADM, ETFA, ETFB, ETFDH, FLAD1, SLC25A32, SLC52A1, SLC52A2, SLC52A3); 5) disorders of ketone body metabolism (CPT1A, CPT2, HMGCL); 6) mitochondrial disorders (DLD). Twenty nine patients (n=29: with idiopathic NDH n=17 and with insulinoma n=12) aged 19 to 66 years underwent a genetic study using this custom panel.RESULTS: As a result of the examination 12 genetic variants (all heterozygous) were identified in 8 patients with idiopathic NDH (47%, 95% CI (23%; 72%)), at that two mutations were detected in three patients: in the genes AGL and HMGCL; ACADM and FLAD1, respectively; and one patient had three mutations: one mutation in the ETFA gene and two mutations in the ABCC8 gene. Frequencies of genetic variants: AGL — 18%, 95% CI (4%; 43%), ETFA — 12% (1%; 36%), HMGCL — 6% (0%; 29%), ALDOB — 6% (0%; 29%), CPT1A — 6% (0%; 29%), ABCC8 — 6% (0%; 29%), ACADM — 6% (0%; 29%), FLAD1 — 6% (0%; 29%). 5 genetic variants (all heterozygous) were identified in 5 patients with insulinoma (42%, 95% ДИ (15%; 72%)). Frequencies of genetic variants: ABCC8 — 17%, 95% CI (2%; 48%), HNF1A — 8% (0%; 38%), ETFDH — 8% (0%; 38%), MPI — 8% (0%; 38%). We did not include benign variants in this analysis. At the same time, clinically significant variants were identified only in one patient from the group with idiopathic NDH (6%, 95% CI (0%; 29%)) in the ABCC8 gene and in one patient from the group with insulinoma (8%, 95% CI (0%; 38%)) in the same gene congenital hyperinsulinism (CHI).CONCLUSION: A panel of 30 genes has been developed, variants of which are associated with a CDGM. The results of our study confirm the possibility of detecting CDGM in adulthood, in particular CHI, and indicate the need for genetic testing, primarily in patients with idiopathic NDH.