Sick sinus syndrome 1

The term 'sick sinus syndrome' encompasses a variety of conditions caused by sinus node dysfunction. The most common clinical manifestations are syncope, presyncope, dizziness, and fatigue. Electrocardiogram typically shows sinus bradycardia, sinus arrest, and/or sinoatrial block. Episodes of atrial tachycardias coexisting with sinus bradycardia ('tachycardia-bradycardia syndrome') are also common in this disorder. SSS occurs most often in the elderly associated with underlying heart disease or previous cardiac surgery, but can also occur in the fetus, infant, or child without heart disease or other contributing factors, in which case it is considered to be a congenital disorder (Benson et al., 2003). Genetic Heterogeneity of Sick Sinus Syndrome Sick sinus syndrome-2 (SSS2; 163800) is caused by mutation in the HCN4 gene (605206). Susceptibility to sick sinus syndrome-3 (SSS3; 614090) is influenced by variation in the MYH6 gene (160710). Sick sinus syndrome-4 (SSS4; 619464) is caused by mutation in the GNB2 gene (139390). [from OMIM]