Taken together, studies from teratogens and basic research on potassium channel function suggest that overactivity of these ion channels and increased K+ conductance underlie the clinical similarities seen in a subgroup of potassium channelopathies characterized by DD/ID, epilepsy, coarse facial features, gingival enlargement, hypertrichosis, and/or nail and phalangeal aplasia or hypoplasia. This evidence concerns the gene KCNA3 and hypertrichosis.