A long QT syndrome that has_material_basis_in autosomal dominant inheritance of a mutation in the KCNJ2 gene which disrupts the rhythm of the heart's lower chambers (ventricular arrhythmia) and results_in an unusually small lower jaw (micrognathia), low-set ears, and an abnormal curvature of the fingers called clinodactyly. [ http://purl.obolibrary.org/obo/ECO_0007638 ]