In a patient with congenital hyperinsulinism, a previously undescribed variant c.4454A>C (HG38, chr11:17394357T>G, coverage depth 256×) in exon 37 of the ABCC8 gene was identified in a homozygous or hemizygous state, resulting in an amino acid substitution p.(Gln1485Pro). The gene discussed is ABCC8; the disease is familial hyperinsulinism.