The congenital long QT syndrome is characterised by the presence of syncopes due 
to torsades de pointe which may degenerate to ventricular fibrillation and cause 
sudden death. These syncopes occur in young subjects with electrocardiographic 
abnormalities and prolongation of the QT interval. Patients with the autosomally 
dominant transmitted Romano-Ward syndrome with normal audition are classically 
opposed to those with the Jervell and Lange-Nielsen autosomally recessive 
syndrome who have bilateral total deafness. Our understanding of the congenital 
long QT syndrome has improved in recent years with respect to the 
physiopathology, diagnosis and treatment, due to research in the fields of 
genetics, electrocardiography and electrophysiology. The diagnosis is based on 
analysis of the phenotype and genotypes. A family enquiry is always necessary to 
detect unrecognised forms. Five culprit genes have been identified for the 
Romano-Ward syndrome. All code for subunits of sodium or potassium channels: two 
a subunits of the potassium channels (QVLQT1 for LQT1, HERG for LQT2), the a 
subunit of the sodium channel INa (SCN5A for LQT3), and two regulatory subunits 
of potassium channels (KCNE1 for LQT5 regulating the KvLQT1 channel and MiRP1 
regulating HERG). The concept of genetic heterogeneity of the congenital long QT 
syndrome may thus be understood: different genes may be responsible for the same 
phenotype. Except for specific cases, the usual treatment is life-long 
betablocker therapy and the avoidance of a large number of drugs, the list of 
which is continually updated. A multicentre trial is underway to validate 
betablocker therapy for the prevention of cardiac events in a LQT1 genotype 
population. Prospective studies will be necessary to assess gene-specific 
treatments.