Congenital long QT syndrome (LQTS) is a rare heart condition characterized by a prolonged QT interval on ECG/EKG and polymorphic ventricular arrhythmias (torsade de pointes). These cardiac arrhythmias may result in recurrent syncope, seizure, or sudden death. Variants in various genes encoding ion channels are associated with different forms of LQTS. The long QT syndrome 1 (LQT1) is caused by variants in the KCNQ1 gene. LQT1 can be inherited in both autosomal dominant and autosomal recessive patterns. Autosomal dominant LQT1 is manifested with variable penetrance.
A 2-bp deletion, c.451_452delCT (p.Leu151Glyfs), in exon 2 of the KCNQ1 gene is the most frequent pathogenic variant found in Amish patients. The homozygous c.451_452delCT variant has been reported in Old Order Amish patients with long QT syndrome and deafness. Heterozygous variants in the KCNQ1 gene have been reported in familial long QT syndrome patients with no hearing loss. This targeted test will specifically analyze the c.451_452delCT variant.
1 - 2 weeks