Focal congenital hyperinsulinism resulting from biallelic loss of function of gene.

Congenital hyperinsulinism (CHI) characterised by inappropriate secretion of insulin despite low blood glucose can result in irreversible brain damage if not promptly treated. The most common genetic cause of hyperinsulinism is the pathogenic variants in and , causing dysregulated insulin secretion. Rapid testing is crucial for all patients because finding a mutation significantly impacts this condition's clinical management. We report a rare case of focal CHI after a homozygous mutation who underwent a selective lesionectomy and required octreotide for euglycaemia.