SCN5A and overlapping connective tissue disease: To our knowledge only one prospective study of children with SCN5A mutations included 442 neonates, where most showed no ECG alterations at birth (44.3%) and the most frequent arrhythmogenic phenotype was isolated PCCD (25.6%), followed by overlap syndrome (15%), LQTS (10.6%) and BrS (1.8%) [15].