Specific mutations in KCNJ11 and ABCC8 cause a syndromic form of neonatal diabetes characterised by severe development delay and neurological features (DEND [Developmental delay, Epilepsy and Neonatal Diabetes] and iDEND syndrome).5, 7 The most common of these mutations is KCNJ11 p.Val59Met which was detected in 26 patients in our cohort. Here, KCNJ11 is linked to Global developmental delay.