1. Centre for Inherited Cardiovascular Diseases, Great Ormond Street Hospital, London, United Kingdom (G.N., E.F., K.D., J.T., E.C., J.P.K.).
2. Institute of Cardiovascular Science, University College London, United Kingdom (G.N., V.K., E.F., J.T., E.C., J.P.K.).
3. Department of Pediatric Cardiology, Royal Hospital for Children, Glasgow, United Kingdom (KML).
4. West of Scotland Centre for Genomic Medicine, Glasgow, United Kingdom (R.M.G.).