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SLC22A5 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SLC22A5 gene

The SLC22A5 gene provides instructions for making the OCTN2 protein, which is essential for transporting carnitine into cells to produce energy for the heart and muscles.

Normal Function

The SLC22A5 gene provides instructions for making a protein called OCTN2 that is found in the heart, liver, muscles, kidneys, and other tissues. This protein is positioned within the cell membrane, where it transports a substance known as carnitine into the cell. Carnitine is mainly obtained from food and is needed to bring certain types of fats (fatty acids) into mitochondria, which are the energy-producing centers within cells. Fatty acids are a major source of energy for the heart and muscles. During periods without food (fasting), fatty acids become the most important energy source for the heart and other muscles.

Health Conditions Related to Genetic Changes

Primary carnitine deficiency

Many variants (also called mutations) in the SLC22A5 gene have been found to cause primary carnitine deficiency. Some of these variants create a premature stop signal in the instructions for making the OCTN2 protein, resulting in an abnormally short, nonfunctional protein. Other variants change single protein building blocks (amino acids) in the OCTN2 protein or prevent the protein from being produced at all.

A lack of functional OCTN2 proteins creates a shortage (deficiency) of carnitine within cells. Without carnitine, fatty acids cannot enter mitochondria and be used to make energy. Reduced energy production can lead to some of the features of primary carnitine deficiency, such as muscle weakness and hypoglycemia. Fatty acids can also build up in cells and damage the liver, heart, and muscles. This abnormal buildup causes the other signs and symptoms of the disorder.

Crohn's disease

MedlinePlus Genetics provides information about Crohn's disease.

Other Names for This Gene

  • CDSP
  • high-affinity sodium dependent carnitine cotransporter
  • novel organic cation transporter 2
  • OCTN2
  • organic cation transporter 5
  • organic cation/carnitine transporter 2
  • S22A5_HUMAN
  • SCD
  • solute carrier family 22 (organic cation transporter), member 5
  • solute carrier family 22 (organic cation/carnitine transporter), member 5

Genomic Location

The SLC22A5 gene is found on chromosome 5.

Frequently Asked Questions

DNA test that sequences the SLC22A5 gene can identify pathogenic variants. If a mutation is found, first‑degree relatives can be offered carrier testing. Identifying carriers allows for early monitoring and, if necessary, preventive supplementation to avoid complications.===
diagnosis is confirmed with a combination of blood tests that measure free carnitine levels (usually below 5 µmol/L is abnormal) and a genetic test that looks for pathogenic variants in the SLC22A5 gene. A urine organic acid profile may also show elevated propionylcarnitine, supporting the diagnosis.
Yes, severe deficiency can cause arrhythmias, cardiomyopathy, or sudden cardiac arrest, especially during fasting or illness. Watch for unexplained fatigue, palpitations, fainting, or chest pain, and seek immediate medical attention if these occur.
Patients are advised to consume a balanced diet rich in carnitine‑containing foods such as red meat, dairy, and fish. In many cases, oral L‑carnitine supplements (typically 50–100 mg/kg/day divided into 2–3 doses) are prescribed to raise tissue carnitine levels and prevent symptoms.
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.

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