In this study we describe a familial case of cardiac-only TS presenting with complex clinical phenotype including prolongation of QT interval, atrial fibrillation, congenital heart disorder, ventricular tachycardia, and cardiac conduction defects caused by mutation R518C and sought to explore computationally possible structural consequences of mutations R518C/H, G402S, and G406R. The gene discussed is CACNA1C; the disease is atrial fibrillation.