Phenotypic heterogeneity in the Romano-Ward syndrome
The Romano-Ward syndrome is a familial disorder inherited as an autosomal dominant trait, the gene of which has been linked to the HLA locus on chromosome 6 or the Harvey-ras oncogene on chromosome 11. The genetic linkage, left and right ventricular function, and the integrity of the baroreflex were studied in subjects from two unrelated families with this condition. Neither family showed genetic linkage to either the HLA locus or to the Harvey-ras gene. Blood pool tomography was used to assess left and right ventricular function: left ventricular wall motion abnormalities were seen only in one family; the degree of dysfunction was related to the presence of symptoms. Minor disturbances of right ventricular function were seen in some subjects from both families, but did not correlate to the presence nor to the severity of symptoms. Using 14 frequencies of cyclical neck suction, the frequency response of the carotid baroreceptor heart-rate reflex was studied. One family had essentially a normal baroreflex. However, all members of the other family had similarly abnormal responses: a higher sensitivity at high and low suction frequencies, suggesting abnormalities of parasympathetic and sympathetic tone respectively. The Romano-Ward syndrome is a heterogeneous disorder: differences in genetic linkage (compared with historical controls), left ventricular function, and baroreflex sensitivity have been demonstrated.