Introduction. Long QT syndrome is a repolarisation disorder of myocardium that results in prolonged QT interval on electrocardiogram. At least 16 genes are linked to this disorder. Long QT syndrome type 8 is caused by CACNA1C mutations. It makes up <1% of all the congenital long QT syndrome cases. CANCA1C gene codes ax subunit of calcium channel CaV1.2. Gain of funclion mutations in CACNA1C are common among Timothy syndrome and long QT syndrome type 8 cases. At least 16 different mutations in CACNA1C gene cause long QT syndrome type 8. Most of these mutations are reported only once, making it hard to establish phenotypic heterogenicity of different genetic variances.
The aim and methods. The aim of this article is to present two ultra-rare long QT syndrome type 8 variants in five individuals diagnosed in Vilnius University Hospital Santaros Klinikos and compare our clinical data with other authors’.
Results. Two of our patients had CACNA1C gene (NM_199460.2) c. 1552C>T р. (Arg518Cys) (rs1057517711) variant which has been linked to severe phenotype of long QT syndrome, hypertrophic cardiomyopathy, congenital heart disease and sudden cardiac death. We also present three individuals with CACNA1C gene (NM_199460.2) с. 2573G>A, p.(Arg858His) (rs786205753) variant which has been linked to syncope, electrical storm and sudden cardiac death. Three of our subjects were actively engaged in sports.
Conclusion. A lot of research has been made on long QT syndrome type 8 pathogenesis. However, due to rareness of the disease and its phenotypical heterogenicity, there is lacking data on treatment and follow-up recommendations
