CPT1B, or Carnitine Palmitoyltransferase 1B, is an enzyme found in the mitochondria of cells. It plays a crucial role in the metabolism of fatty acids by facilitating the transport of long-chain fatty acids into the mitochondria, where they can be oxidized for energy. This process is essential for maintaining energy balance in the body. Mutations in the CPT1B gene can lead to various metabolic disorders, including CPT1B deficiency. This condition can result in symptoms such as hypoketotic hypoglycemia and muscle weakness, particularly during fasting or prolonged exercise. Understanding CPT1B is important for diagnosing and managing these metabolic issues.