Drug induced torsades: a forme furste of LQTS

A new study published in Circulation: Arrhythmia and Electrophysiology found LQTS mutations as frequently in drug induced cases as in congenital cases:

Conclusions— dLQTS had a similar positive mutation rate compared with cLQTS, whereas the functional changes of these mutations identified in dLQTS were mild. When IKr-blocking agents produce excessive QT prolongation (dLQTS), the underlying genetic background of the dLQTS subject should also be taken into consideration, as would be the case with cLQTS; dLQTS can be regarded as a latent form of long-QT syndrome.

We've suspected this for a long time to explain the fact that drug induced TDP appears to be idiosyncratic.