Conducted a systematic review following PRISMA guidelines. Searched PubMed and Embase databases up to October 2019. Used specific search strategies focusing on intellectual disability and potassium channelopathies. Included cohorts, case-controls, cross-sectionals, case series, and case reports. Selected studies with patients having ID/GDD and potassium channel gene mutations. Excluded studies with other channelopathies or gene mutations. This evidence concerns the gene KCNA3 and Global developmental delay.