Short QTc interval (331 ms) as well as narrow and peaked T waves observed in two male 9-year-old identical twins, also showing epilepsy and severe signs and symptoms of autism spectrum disorder. Novel heterozygous variant in KCNJ2 identified, which was also found in the mother. When 8-year-old, a novel heterozygous variant in KCNJ10, encoding the Kir4.1 protein and also inherited from the mother, was reported in relation to the neurological findings. The gene discussed is KCNJ10; the disease is autism spectrum disorder.