Clinical and molecular data from 61 Brazilian cases of Congenital Hyperinsulinemic Hypoglycemia

Genetics and Natural History of Non-pancreatectomized Patients With Congenital Hyperinsulinism Due to Variants in ABCC8

CONTEXT

Patients with congenital hyperinsulinism due to ABCC8 variants generally present severe hypoglycemia and those who do not respond to medical treatment typically undergo pancreatectomy. Few data exist on the natural history of non-pancreatectomized patients.

OBJECTIVE

This work aims to describe the genetic characteristics and natural history in a cohort of non-pancreatectomized patients with congenital hyperinsulinism due to variants in the ABCC8 gene.

METHODS

Ambispective study of patients with congenital hyperinsulinism with pathogenic or likely pathogenic variants in ABCC8 treated in the last 48 years and who were not pancreatectomized. Continuous glucose monitoring (CGM) has been periodically performed in all patients since 2003. An oral glucose tolerance test was performed if hyperglycemia was detected in the CGM.

RESULTS

Eighteen non-pancreatectomized patients with ABCC8 variants were included. Seven (38.9%) patients were heterozygous, 8 (44.4%) compound heterozygous, 2 (11.1%) homozygous, and 1 patient carried 2 variants with incomplete familial segregation studies. Seventeen patients were followed up and 12 (70.6%) of them evolved to spontaneous resolution (median age 6.0 ± 4 years; range, 1-14). Five of these 12 patients (41.7%) subsequently progressed to diabetes with insufficient insulin secretion. Evolution to diabetes was more frequent in patients with biallelic variants in the ABCC8 gene.

CONCLUSION

The high remission rate observed in our cohort makes conservative medical treatment a reliable strategy for the management of patients with congenital hyperinsulinism due to ABCC8 variants. In addition, a periodic follow-up of glucose metabolism after remission is recommended, as a significant proportion of patients evolved to impaired glucose tolerance or diabetes (biphasic phenotype).

Congenital Hyperinsulinism Caused by a De Novo Mutation in the ABCC8 Gene - A Case Report

Congenital hyperinsulinism (CHI) is a rare genetic disorder characterized by inappropriate insulin secretion and severe hypoglycaemia. There are two histological subtypes: diffuse and focal form. Diffuse form is most common in autosomal recessive mutations in ABCC8/KCNJ11 gene, while focal CHI is caused a paternally inherited mutation and a somatic maternal allele loss. Here we report a case of a term male infant presented with severe hyperinsulinaemic hypoglycaemia. Gene panel testing was performed to give rapid genetic diagnosis. We detected the c.4415-13G>A heterozygous mutation in the ABCC8 gene. Targeted genetic testing of the parents proved the de novo origin of the mutation. The mutation has been previously described. The infant received octreotide treatment and is prepared for 18-fluoro-dopa PET-CT examination in order to localize the lesion. Rapid genetic testing might be crucial in the clinical management strategy, with decision algorithms taking into account of the genetic status of the patient.