GENETIC-LINKAGE ANALYSES OF ROMANO-WARD SYNDROME (RWS) IN 13 JAPANESEFAMILIES

Romano-Ward syndrome (RWS) is an autosomal dominant disorder character ized by prolongation of the electrocardiographic QT interval, with cli nical manifestations that include recurrent syncope and sudden death f rom ventricular arrhythmias. Presymptomatic diagnosis is difficult bec ause of the variability in these signs among carriers, but it is impor tant for clinical management to prevent sudden cardiac death. To find an LQT (long QT) locus in Japanese patients and to identify DNA marker s useful for presymptomatic diagnosis, linkage analyses were undertake n in 13 Japanese families with RWS patients by means of two DNA marker s located an 11p15.5. One of these marker loci, HRAS, was previously r eported to be tightly linked to the LQT locus in another ethnic group. Our analyses of homogeneity suggest evidence for genetic heterogeneit y of RWS within the Japanese population.