KCNJ11 and DEND syndrome: In about 20%–30% of the patients, the potassium channel mutations (mainly Kir6.2 mutations) also affect the KATP channel complexes in multiple neurons in the brain [83] leading to deactivation of the inhibitory neurons and more severe syndromes involving neurological and psychological manifestations in addition to NDM [76,83,84,85], such as developmental delay and epilepsy (DEND syndrome), intermediate DEND syndrome without epilepsy, ataxia, muscle weakness, attention deficit hyperactivity syndrome, anxiety, autism, or sleeping disorders [84,86,87,88].