The Romano Ward long QT syndrome (LQTS) has an autosomal dominant mode of inheritance. Patients suffer from syncopal attacks often resulting in sudden cardiac death. The main diagnostic parameter is a prolonged QT(c) interval as judged by electro-cardiographic investigation. LQTS is a genetically heterogeneous disease with four loci having been identified to date: chromosome 11p15.5 (LQT1), 7q35-36 (LQT2), 3p21-24 (LQT3) and 4q25-26 (LQT4). The corresponding genes code for potassium channels KVLQT1 (LQT1) and HERG (LQT2) and the sodium channel SCN5A (LQT3). The KVLQT1 gene is characterized by six transmembrane domains (S1-S6), a pore region situated between the S5 and S6 domains and a C-terminal domain accounting for approximately 60% of the channel. This domain is thought to be co-associated with another protein, viz. minK (minimal potassium channel). We have studied a Romano Ward family with several affected individuals showing a severe LQTS phenotype (syncopes and occurrence of sudden death). Most affected individuals had considerable prolongations of QT(c). By using haplotyping with a set of markers covering the four LQT loci, strong linkage was established to the LQT1 locus, whereas the other loci (LQT2, LQT3 and LQT4) could be excluded. Single-strand conformation polymorphism analysis and direct sequencing were used to screen the KVLQT1 gene for mutations in the S1-S6 region, including the pore domain. We identified a Gly-216-Arg substitution in the S6 transmembrane domain of KVLQT1. The mutation was present in all affected family members but absent in normal control individuals, providing evidence that the mutated KVLQT1-gene product indeed caused LQTS in this family. The mutated KVLQT1-gene product thus probably results in a dominant negative suppression of channel activity.
The Romano Ward long QT syndrome ( LQTS ) has an autosomal dominant mode of inheritance . Patients suffer from syncopal attacks often resulting in sudden cardiac death . The main diagnostic parameter is a prolonged QT(c ) interval as judged by electro - cardiographic investigation . LQTS is a genetically heterogeneous disease with four loci having been identified to date : chromosome 11p15.5 ( LQT1 ) , 7q35 - 36 ( LQT2 ) , 3p21 - 24 ( LQT3 ) and 4q25 - 26 ( LQT4 ) . The corresponding genes code for potassium channels KVLQT1 ( LQT1 ) and HERG ( LQT2 ) and the sodium channel SCN5A ( LQT3 ) . The KVLQT1 gene is characterized by six transmembrane domains ( S1-S6 ) , a pore region situated between the S5 and S6 domains and a C - terminal domain accounting for approximately 60 % of the channel . This domain is thought to be co - associated with another protein , viz . minK ( minimal potassium channel ) . We have studied a Romano Ward family with several affected individuals showing a severe LQTS phenotype ( syncopes and occurrence of sudden death ) . Most affected individuals had considerable prolongations of QT(c ) . By using haplotyping with a set of markers covering the four LQT loci , strong linkage was established to the LQT1 locus , whereas the other loci ( LQT2 , LQT3 and LQT4 ) could be excluded . Single - strand conformation polymorphism analysis and direct sequencing were used to screen the KVLQT1 gene for mutations in the S1-S6 region , including the pore domain . We identified a Gly-216-Arg substitution in the S6 transmembrane domain of KVLQT1 . The mutation was present in all affected family members but absent in normal control individuals , providing evidence that the mutated KVLQT1-gene product indeed caused LQTS in this family . The mutated KVLQT1-gene product thus probably results in a dominant negative suppression of channel activity .
What is the mode of inheritance of Romano Ward long QT syndrome?
What is the mode of inheritance of Romano Ward long QT syndrome ?
autosomal dominant
autosomal dominant