Sudden infant death.

The association between Long QT syndrome (LQTS) and sudden infant death syndrome (SIDS) remains highly topical and even polarizing. Because the landmark Italian study of the QT interval and SIDS triggered extensive controversy, there has been a substantial and commendable effort to establish LQTS as one of the true causes of SIDS. The motivation underlying this effort is based on the fact that true LQTS is a potentially preventable cause of sudden death. Many questions, however, remain. Where and how does LQTS fit into the spectrum of SIDS? Have we reached the stage where we can describe a typical phenotype for SIDS because of LQTS? Is it conceivable that some SIDS victims die with contribution from a channelopathy genetic variant, rather than because of it in isolation? After SIDS, can we identify those cases that are more likely to have been LQTS and, therefore, warrant genetic testing? When should family clinical screening be undertaken? To facilitate clarity of academic discussion, research and clinical care, we suggest a paradigm shift in how to analytically view the LQTS–SIDS association.