SLC22A5 is a gene that provides instructions for making a protein involved in the transport of certain molecules across cell membranes. This protein primarily helps in the uptake of carnitine, a substance essential for energy production in cells, particularly in muscle and heart tissues. Mutations in the SLC22A5 gene can lead to a condition known as primary carnitine deficiency, which results in low levels of carnitine in the body. This deficiency can cause various health issues, including muscle weakness, heart problems, and metabolic disturbances, highlighting the importance of this gene in maintaining overall health.