SLC22A5 (Solute Carrier Family 22 Member 5): SLC22A5 is a protein, also known as OCTN2, that acts as a key carnitine transporter in the body. It enables the cellular uptake of carnitine, a compound essential for transporting fatty acids into mitochondria for energy production. This process is crucial for energy metabolism in tissues such as the heart and muscles. Mutations in the SLC22A5 gene can lead to primary carnitine deficiency, a condition characterised by muscle weakness and cardiomyopathy, emphasising its vital role in metabolic health and energy balance.