In some cases, paternal isodisomy of chromosome 11p15 occurs in multiple tissues, causing Beckwith-Wiedemann Syndrome spectrum (BWSp); severe diazoxide-unresponsive HI can occur in BWSp due to 11pUPD when there is a concurrent paternally inherited ABCC8 or KCNJ11 disease-causing variant [82]. This evidence concerns the gene KCNJ11 and Beckwith-Wiedemann syndrome.