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SLC25A20 gene

Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SLC25A20 gene

The SLC25A20 gene provides instructions for the carnitine-acylcarnitine translocase (CACT) protein, which is essential for converting fats into energy.

Normal Function

The SLC25A20 gene provides instructions for making a protein called carnitine-acylcarnitine translocase (CACT). This protein is essential for fatty acid oxidation, a multistep process that breaks down (metabolizes) fats and converts them into energy. Fatty acid oxidation takes place within mitochondria, which are the energy-producing centers in cells. A group of fats called long-chain fatty acids must be attached to a substance known as carnitine to enter mitochondria. Once these fatty acids are joined with carnitine, the CACT protein transports them into mitochondria. Carnitine is then removed from the long-chain fatty acid and transported back out of mitochondria by the CACT protein. Fatty acids are a major source of energy for the heart and muscles. During periods of fasting, fatty acids are also an important energy source for the liver and other tissues.

Health Conditions Related to Genetic Changes

Carnitine-acylcarnitine translocase deficiency

At least 27 mutations in the SLC25A20 gene have been found to cause carnitine-acylcarnitine translocase (CACT) deficiency. Although these mutations change the structure of the CACT protein in different ways, they all lead to a shortage (deficiency) of the protein. Without enough functional CACT protein, long-chain fatty acids cannot be transported into mitochondria. As a result, these fatty acids are not converted to energy. Reduced energy production can lead to some of the features of CACT deficiency, such as low blood glucose (hypoglycemia) and low levels of the products of fat breakdown (hypoketosis). Fatty acids and long-chain acylcarnitines (fatty acids still attached to carnitine) may also build up in cells and damage the liver, heart, and muscles. This abnormal buildup causes the other signs and symptoms of the disorder.

Other Names for This Gene

  • CAC
  • CACT
  • carnitine-acylcarnitine carrier
  • carnitine/acylcarnitine translocase
  • MCAT_HUMAN
  • solute carrier family 25 (carnitine/acylcarnitine translocase), member 20

Frequently Asked Questions

Infants often present within the first few days of life with poor feeding, lethargy, seizures, profound hypoglycemia, low ketone bodies (hypoketosis), and hepatomegaly. Laboratory tests may reveal elevated long‑chain acylcarnitines (C14‑C18) and a characteristic pattern on newborn screening.
Initial suspicion is based on the acylcarnitine profile from dried blood spots. Confirmation requires enzymatic studies in fibroblasts or muscle tissue showing reduced CACT activity, followed by molecular genetic testing (sequencing of SLC25A20) to identify pathogenic mutations.
Management focuses on limiting long‑chain fatty acid intake and providing a high‑carbohydrate, low‑fat diet supplemented with medium‑chain triglycerides (MCT oil), which can bypass the CACT step. Frequent meals or continuous nocturnal feeds help maintain glucose stability, and during illness, intravenous glucose (10 % dextrose) is often required.
Rapid correction of hypoglycemia with intravenous 10 % dextrose, avoidance of fasting, and administration of carnitine (if not contraindicated) are first‑line. In severe cases, extracorporeal membrane oxygenation (ECMO) or liver transplantation may be considered, but early metabolic stabilization is critical.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.