The trio‐exome analysis revealed a clear pathogenic nonsense variant in ABCC8 inherited from the clinically nonaffected mother, resulting in a premature stop codon (ABCC8, NM_000352.6:c.2800C>T, depth: 92×, allele distribution 43/49) which strengthened the suspicion of a diffuse autosomal recessive form of familial hyperinsulinism, due to the mostly paternal inheritance of the monoallelic‐recessive focal forms of CHI. Here, ABCC8 is linked to hyperinsulinism.