Abstract: It is reported that the incidence of congenital long QT syndrome (cLQTS) is very low, with the incidence of LQTS caused by transient receptor potential melastatin 4 (TRPM4) being even lower, leading to less research on the gene TRPM4. We reported a case of an elderly male patient presenting with frequent syncopal episodes since the age of 20. Electrocardiography showed sinus bradycardia (mean heart rate 59 beats), prolonged QT interval (540ms), and torsade de pointes. His sister also had experienced an episode of syncope, but his other families had not. A novel mutation in the TRPM4 gene was discovered in this patient and his sister, according to genetic analysis. All in all, we provided a new heterozygous shift mutation (NM_017636: exon4: c.434delC, p. Ala145ValfsTer133) on TRPM4, which has never been reported in the past and thus may hopefully serve as useful feedback information for genetic pathogenesis of cLQTS caused by TRPM4 variants.
Keywords: long QT syndrome, LQTS, TRPM4, mutation