Developmental changes in cardiac expression of KCNQ1 and SCN5A spliceoforms: Implications for sudden unexpected infant death

Sudden unexpected infant death (SUID) occurs unpredictably and remains unexplained after scene investigation and autopsy. Approximately 1 in 7 cases of SUID can be related to a cardiac cause, and developmental regulation of cardiac ion channel genes may contribute to SUID. The goal of this study was to investigate the developmental changes in the spliceoforms of SCN5A and KCNQ1, 2 genes implicated in SUID. Using reverse transcription quantitative real-time polymerase chain reaction, we quantified expression of SCN5A (adult and fetal) and KCNQ1 (KCNQ1a and b) spliceoforms in 153 human cardiac tissue samples from decedents that succumbed to SUID (“unexplained”) and other known causes of death (“explained noncardiac”). There is a stepwise increase in the adult/fetal SCN5A spliceoform ratio from