The patient was reassured regarding the low statistical risk of CHI in her children (1/600) (9), as her ABCC8 variant had a recessive mechanism, would be maternally transmitted and there would be a low risk for her husband to be a carrier of a recessive variant in ABCC8. However, unfortunately, her twins were born with severe diffuse CHI due to the transmission of her ABCC8 pathogenic variant and an unexpected variant from her asymptomatic husband. Here, ABCC8 is linked to congenital isolated hyperinsulinism.