ABCC8 and congenital isolated hyperinsulinism: Based on these findings, a diagnosis of CHI was made and genetic testing of the child and both parents showed that she is a compound heterozygote for an ABCC8 missense mutation, p.R1419C (c.4255C>T) and a deletion of ABCC8 exon 3 (c.291-?_412+?del) thus confirming diffuse disease.