Timothy syndrome – Cardiology MCQ

All of the following are features of Timothy syndrome except:

a) CACNA1C mutation

b) Named after Katherine W. Timothy

c) Phase 1 of action potential is affected by gene mutation

d) Multisystem disorder

Correct answer: c) Phase 1 of action potential is affected by gene mutation

Cav1.2 calcium channel is affected by CACNA1C mutation in Timothy syndrome. This channel is important in the phase 2 (plateau phase) of cardiac action potential. Timothy syndrome is characterised by marked prolongation of QT interval, syndactyly, congenital heart disease, cognitive abnormalities, and intermittent hypoglycemia. It is designated as LQT8.