DIAGNOSTIC OF LONG QT-SYNDROME

Electrocardiographic and clinical characteristics are currently used a s diagnostic criteria for the long QT-syndrome. In borderline electroc ardiographic findings associated with unclear syncope, it is often dif ficult to ensure or exclude long QT-syndrome. Schwartz and coworkers t herefore created a point system as a guide in clinical decision making . In recent years genetic diagnostics have entered the arena of long-Q T assessment. Aside from new insights into the pathophysiology of the long QT-disorder, it is expected that genetic diagnostics will offer s ubstantial help to ascertain long QT-syndrome in patients with borderl ine electrocardiographic and clinical findings and improve risk strati fication in long-QT family members.Performing linkage analysis, coupli ng of autosomal-dominant congenital long QT-syndrome (Romano-Ward Synd rome) to chromosomes 11 (LQT1/11p15.5), 3 (LQT3/3p21), 7 (LQT2/7q35), and 4 (LQT4/4q25-27) was demonstrated. More recently, the disease gene s in long QT-syndrome 1, 2, and 3 could be identified. Analysis of the base-pair sequence allowed detection of several different mutations i n different families illustrating genetic heterogeneity. Aside from di agnostic aspects, molecular genetics may also guide pharmacological th erapy by identifying the specific ion-channel disorder leading to QT-p rolongation and sudden death.