SCN4A is a gene that provides instructions for making a protein called sodium channel type IV alpha subunit. This protein is essential for the proper functioning of nerve and muscle cells, as it helps regulate the flow of sodium ions across cell membranes. Sodium channels play a crucial role in generating and transmitting electrical signals in these cells. Mutations in the SCN4A gene can lead to various health conditions, including myotonia and periodic paralysis. These disorders affect muscle function, causing symptoms like muscle stiffness or weakness. Understanding SCN4A is important for diagnosing and developing treatments for these genetic conditions.