SLC25A20

The SLC25A20 gene provides instructions for making a transporter called carnitine-acylcarnitine translocase. Carnitine, a naturally occurring substance obtained mainly from the diet, is necessary for cells to break down fats for energy. The carnitine-acylcarnitine translocase transporter is made in large amounts in the heart, muscles used for movement (skeletal muscles), and the liver. This transporter transfers carnitine linked to fats called long-chain fatty acids into mitochondria, the energy-producing centers within cells. Carnitine-acylcarnitine translocase also transports free carnitine out of the mitochondria.

carnitine-acylcarnitine translocase deficiency - caused by mutations in the SLC25A20 gene

At least 26 mutations responsible for carnitine-acylcarnitine translocase deficiency have been identified in the SLC25A20 gene. Many of these mutations lead to the improper substitution of one amino acid (a building block of proteins) for another amino acid in carnitine-acylcarnitine translocase. These substitutions dramatically reduce the activity of this transporter. Other mutations delete part of the SLC25A20 gene or insert a premature stop signal in the gene's instructions for making this transporter. As a result, very little functional carnitine-acylcarnitine translocase is made.

With a shortage of functional carnitine-acylcarnitine translocase, long-chain fatty acids cannot be broken down and processed. As a result, these fatty acids are not converted to energy, which can lead to characteristic signs and symptoms of carnitine-acylcarnitine translocase deficiency, such as low blood sugar (hypoglycemia) and muscle weakness. Excess long-chain fatty acids, with or without carnitine attached to them can affect the electrical properties of cardiac (heart) cells. This accumulation of fatty-acids can cause an irregular heartbeat (arrhythmia) that can lead to cardiac arrest. Fatty acids may also build up in tissues and can damage the heart, liver, and muscles, causing more serious complications.