Is there a relation between SIDS and long QT syndrome?

The condition of syndactyly with long QT syndrome is a very severe form of the disease, caused by a calcium channel dysfunction. 10 Jervell and Lange-Neilsen syndrome is also very severe, due to the co-inheritance of two potassium channel defects which also results in deafness, and presents with an autosomal recessive type of inheritance. 11 Long QT type Chromosome Gene Percentage of genotyped families affected Ion channel Typical trigger for syncope/sudden death Percentage of cardiac events occurring during rest/sleep 1 11 KCNQ1 (KVLQT1) 42% Potassium (Iks), loss of function Exercise (especially swimming) 3% 2 7 KCNH2 (HERG) 45% Potassium (Ikr), loss of function Emotion/loud noise (especially waking from sleep) 29% 3 3 SCN5A 7% Sodium (INa), gain of function Rest/sleep 39% Each of the genotypes has its own phenotype expressed as characteristic T wave abnormalities on the ECG and by the type of trigger for syncope or sudden death. 12 There is considerable overlap between the phenotypes; however, syncope or sudden death are classically triggered by physical exertion (especially swimming) in long QT type 1, and emotional excitement or loud noise (especially noises causing waking from sleep) in type 2. Future research may identify a link to milder forms of long QT syndrome, analogous to the heterogeneic response of the population to drugs known to prolong the QT interval. 7 However, infants usually respond to physiological stress by extreme bradycardia rather than ventricular tachycardia.