Congenital long QT syndromes: clinical features, molecular genetics and genetic testing.
Congenital long QT syndrome (LQTS) is a primary electrical disease characterized by a prolonged QT interval in the surface electrocardiogram and increased predisposition to a typical polymorphic ventricular tachycardia, termed Torsade de Pointes. Most patients with LQTS are asymptomatic and are diagnosed incidentally based on an electrocardiogram. Symptomatic patients may suffer from severe cardiac events, such as syncope and/or sudden cardiac death. Autosomal dominant forms are caused by heterozygous mutations in genes encoding the components of the ion channels. The autosomal recessive form with congenital deafness is also known as Jervell and Lang-Nielsen syndrome. It is caused by homozygous mutations or certain compound heterozygous mutations. Depending on the genetic defects, there are differences in the age of onset, severity of symptoms, and number of cardiac events and event triggers. With advances in gene technology, it is now feasible to perform genetic testing for LQTS, especially for those with family history. Identification of the mutation will lead to better management of symptoms and more targeted treatment, depending on the underlying genetic defect, resulting in a reduction of mortality and cardiac events.
Ching
Chi-Keong
CK
National Heart Centre, Department of Cardiology, National Heart Centre, Mistri Wing 17 Third Hospital Avenue, Singapore 168752, Republic of Singapore.
Tan
Ene-choo
EC
D051638:Ether-A-Go-Go Potassium Channels / Q000235:genetics; D005799:Genes, Dominant; D005808:Genes, Recessive; D020022:Genetic Predisposition to Disease; D005821:Genetic Techniques; D005820:Genetic Testing / Q000379:methods*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis* / Q000235:genetics*; D008967:Molecular Biology / Q000379:methods; D025202:Molecular Diagnostic Techniques; D009154:Mutation
D051638:Ether-A-Go-Go Potassium Channels