Genetic Variants in Potassium Channel Genes and Their Clinical Implications in Kazakhstani Patients with Cardiac Arrhythmias.

Background/Objectives: Cardiac arrhythmias are among the leading causes of sudden cardiac death (SCD). Pathogenic variants in potassium channel genes play a key role in inherited arrhythmia syndromes, yet their contribution in Central Asian populations remains poorly characterized. Methods: We performed targeted next-generation sequencing (NGS) using a 96-gene custom Haloplex panel in 79 Kazakhstani patients with clinically diagnosed arrhythmias, including atrioventricular block, sick sinus syndrome, and atrial fibrillation. Detected variants in potassium channel genes were classified according to ACMG guidelines and correlated with clinical phenotypes. Results: A total of 52 variants were identified across 11 potassium channel genes. Two likely pathogenic variants (KCNH2 p.Cys66Gly and p.Arg176Trp) and six variants of uncertain significance (VUS) in KCNQ1, KCNE2, KCNE3, and KCNJ8 were detected. Two novel previously unreported variants were found in KCNE5 and KCND3. Patients harboring pathogenic variants commonly presented with early-onset arrhythmias or a positive family history of cardiovascular disease. Carriers of KCNH2 variants exhibited mild QT prolongation and recurrent syncope. Conclusions: This is the first genetic study of potassium channel gene mutations in Kazakhstani patients with cardiac arrhythmias. The detection of pathogenic and novel variants highlights the clinical utility of integrating genetic testing into diagnostic and management pathways for arrhythmia syndromes. Population-specific genomic data are essential for improving risk stratification, guiding medication safety, and enabling cascade family screening in Central Asia.