In contrast to the Romano-Ward (R-W) syndrome, the Jervell and Lange-Nielsen 
(J-LN) syndrome is an autosomal recessive inherited disease characterized by 
QT-prolongation in the electrocardiogram (ECG) and recurrent syncopal attacks 
which are also typical for the R-W syndrome, but also by congenital deafness. 
Recently, defect alleles in the genes for KCNQ1 and KCNE1 have been identified 
in patients with the J-LN syndrome. These genes may be causative for the R-W 
syndrome as well but in J-LN patients, they are only present in the homozygote 
or compound heterozygote form. In the present paper, we review the clinical and 
genetic similarities and differences of the J-LN and the R-W syndrome as well as 
the diagnostic and therapeutic management of these patients and their family 
members.