TRPM4 and cardiac arrhythmia: Patient 6 also had the heterozygous TRPM4 above, in addition to a second category 1.2 variant in the arrhythmia associated gene ABCC9—heterozygous c.2200G>A (p.V734I), NM_005691, rs61688134 (frequency of approximately 1% in the 1000G database and 0.9% in the ESP database and 0.7% in the ExAC database).