Long QT syndrome
For example, an infant with MCAD deficiency might die by "classical SIDS" if found swaddled and prone, with its head covered, in an overheated room where parents were smoking. Genes indicating susceptibility to MCAD and Long QT syndrome do not protect an infant from dying of classical SIDS. Therefore, the presence of a susceptibility gene, such as for MCAD, means the infant might have died either from SIDS or from MCAD deficiency. It is currently impossible for a pathologist to distinguish between them.