Sick Sinus Syndrome 1, also known as sinus node disease, familial, autosomal recessive, is related to sick sinus syndrome 2 and sick sinus syndrome 3. An important gene associated with Sick Sinus Syndrome 1 is SCN5A (Sodium Voltage-Gated Channel Alpha Subunit 5). Affiliated tissues include heart and colon, and related phenotypes are prolonged qt interval and atrioventricular block