We have over 20,000 different genes in the body. These genes are like instruction manuals for how to build a protein, and each protein has an important function that helps to keep our body working how it should. The SCN5A gene makes a protein called the SCN5A (or sodium voltage-gated channel alpha subunit 5) protein that helps to build sodium channels in the body. These sodium channels allow cells to make and transmit signals which help to make the heart beat at a normal rhythm. The sodium channels that are made by the SCN5A gene are primarily in the heart muscles.
If someone has a harmful change (called a pathogenic variant) in one of their SCN5A genes, then their body is not going to make enough of the SCN5A protein as it should. If there is not enough SCN5A protein, then there will not be enough sodium channels. This would mean that the heart’s ability to send these signals is not going to work as well as it should. This can lead to several different types of heart conditions, including Brugada syndrome, familial dilated cardiomyopathy, Romano-Ward syndrome (a common type of Long QT syndrome), and left ventricular noncompaction.
Pathogenic variants in the SCN5A gene are passed through a family in an autosomal dominant pattern, meaning that anyone who carries the variant has a 50% chance to pass it down to any children they have. Women and men both have the SCN5A gene and have the same chances to inherit and pass down pathogenic variants.
Genetic testing for pathogenic variants in SCN5A is currently available, but there are a few different ways to approach testing: