Book a test
On this page
⚠ Educational content only Not medical or genetic advice. Speak with a healthcare provider or genetic counsellor before acting on anything here.

SLC25A20

solute carrier family 25 member 20

The SLC25A20 gene encodes the carnitine-acylcarnitine translocase (CACT) protein, which is vital for transporting fatty acids into mitochondria for energy production. The SLC25A20 gene is responsible for producing the carnitine-acylcarnitine translocase (CACT) protein.

Chromosome 3p21.31 Autosomal recessive HGNC:1421 Tier C
SLC25A20 3p21.31 p arm q arm 3

SLC25A20 is located on the short (p) arm of chromosome 3, at band 3p21.31. Arm ratio per GRCh38 - banding schematic.

Explore chromosome 3 in the library →

Available at Jeen Health

Clinical tests that include this

Carrier Screening panel
SLC25A20 is 1 of 1,008 genes on this panel
Expanded carrier screening for recessive and X-linked conditions
Newborn Genetic Screening panel
SLC25A20 is 1 of 258 genes on this panel
Genomic newborn screening for actionable paediatric conditions

Overview

The SLC25A20 gene, also known as solute carrier family 25 member 20, provides the genetic instructions for creating the carnitine-acylcarnitine translocase (CACT) protein. This protein is fundamental for the body's ability to metabolise fats, specifically long-chain fatty acids, into energy. Proper function of SLC25A20 is essential for cellular energy production, particularly in tissues like the heart and muscles, and during periods of fasting.

What the gene does

The SLC25A20 gene directs the synthesis of the carnitine-acylcarnitine translocase (CACT) protein. This protein is a key component in the process of fatty acid oxidation, which occurs within the mitochondria, the energy-generating organelles of cells. CACT facilitates the transport of long-chain fatty acids, which are first linked to carnitine, into the mitochondrial matrix. Once inside, carnitine is removed from the fatty acid and subsequently transported back out of the mitochondria by the CACT protein, allowing for further transport cycles. This mechanism ensures that fats can be efficiently broken down to provide energy, which is particularly important for the heart and muscle function, and acts as a significant energy source for the liver and other tissues during fasting states.

Video: Genetics 101

Chromosome location

The SLC25A20 gene is located on chromosome 3 at position 3p21.31. This specific genomic location provides the physical address for the gene within the human genome.

Protein structure

The SLC25A20 gene codes for a protein that is 301 amino acids long. This protein contains several key structural regions: a Solcar 1 (Repeat) domain spanning amino acids 8-99, a Solcar 2 (Repeat) domain from amino acids 108-196, and a Solcar 3 (Repeat) domain situated between amino acids 207-293.

Domain map · 301 amino acids
Solcar 1 (8–99)Solcar 2 (108–196)Solcar 3 (207–293)Solcar 18–99Solcar 2108–196Solcar 3207–2931~151301
Repeat - repeating structural motif
🧬 Explore 3D structure on AlphaFold
UniProt:O43772Length:301 aaStructure:AlphaFold

Key variants

Genetic variations within the SLC25A20 gene can alter the structure and function of the carnitine-acylcarnitine translocase protein. These changes can impair the protein's ability to transport fatty acids, affecting the body's energy metabolism. Different genetic changes may impact the protein in various ways, but they generally lead to a reduced amount or activity of functional CACT protein.

The table below shows the top 10 pathogenic or likely-pathogenic variants currently classified in ClinVar for SLC25A20.
View all on ClinVar →

Sample of pathogenic variants

10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.

Variant (HGVS) Protein change Classification Evidence Associated condition
c.109C>T
single nucleotide variant
 p.Arg37Ter Pathogenic/Likely pathogenic ★★☆☆ Carnitine acylcarnitine translocase deficiency
c.121C>T
single nucleotide variant
 p.Gln41Ter Pathogenic/Likely pathogenic ★★☆☆ Carnitine acylcarnitine translocase deficiency
c.125del
Deletion
 p.Pro42fs Pathogenic/Likely pathogenic ★★☆☆ Carnitine acylcarnitine translocase deficiency
c.191_192del
Deletion
 p.Leu63_Phe64insTer Pathogenic ★★☆☆ Carnitine acylcarnitine translocase deficiency
c.244del
Deletion
 p.Val82fs Pathogenic/Likely pathogenic ★★☆☆ Carnitine acylcarnitine translocase deficiency
c.301C>T
single nucleotide variant
 p.Gln101Ter Pathogenic ★★☆☆ Carnitine acylcarnitine translocase deficiency
c.542del
Deletion
 p.Pro181fs Pathogenic/Likely pathogenic ★★☆☆ Carnitine acylcarnitine translocase deficiency
c.645dup
Duplication
 p.Gly216fs Pathogenic/Likely pathogenic ★★☆☆ Carnitine acylcarnitine translocase deficiency
c.706C>T
single nucleotide variant
 p.Arg236Ter Pathogenic ★★☆☆ Carnitine acylcarnitine translocase deficiency
c.718+1G>C
single nucleotide variant
 - Pathogenic ★★☆☆ Carnitine acylcarnitine translocase deficiency

Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.

Associated conditions

Pathogenic variants in the SLC25A20 gene are known to cause carnitine-acylcarnitine translocase deficiency. This inherited condition affects the body's capacity to convert long-chain fatty acids into energy, leading to a build-up of un-metabolised fats and a shortage of energy.

Inheritance pattern

Conditions caused by pathogenic SLC25A20 variants typically follow autosomal recessive inheritance.

♀ Carrier parent 1 altered copy ♂ Carrier parent 1 altered copy Affected Carrier Carrier Unaffected Affected Carrier Unaffected Circles = females · Squares = males

When both parents are carriers, each child has a 25% chance of being affected, 50% of being a carrier, and 25% of being unaffected.

Carrier frequency by population How common is heterozygous SLC25A20 carrier status across ancestry groups?

UK clinical status

SLC25A20 is recognised in several UK NHS national genomic medicine panels. It is listed as 'green' in the DDG2P, Foetal anomalies (R21), Hyperammonaemia, Likely inborn error of metabolism (R98), Mitochondrial disorders, Paediatric or syndromic cardiomyopathy (R135), and Undiagnosed metabolic disorders panels.

Green-listed
High evidence · clinically actionable in NHS testing
Included in NHS GMS signed-off panels
Fetal anomalies · R21 NHS GMS → Likely inborn error of metabolism · R98 NHS GMS → Paediatric or syndromic cardiomyopathy · R135 NHS GMS → DDG2P NHS GMS → Mitochondrial disorders NHS GMS →
NHS Genomic Medicine Service Jeen carrier screening

Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory

Frequently asked questions

What does the SLC25A20 gene do?

The SLC25A20 gene provides instructions for making the carnitine-acylcarnitine translocase (CACT) protein. This protein is essential for transporting long-chain fatty acids into mitochondria, where they are broken down to produce energy for the body.

What condition is associated with SLC25A20 gene variants?

Variants in the SLC25A20 gene are associated with carnitine-acylcarnitine translocase deficiency. This condition impairs the body's ability to use certain fats for energy, which can lead to various metabolic problems.

How do variants in SLC25A20 affect the body?

Variants in SLC25A20 can lead to a deficiency of the CACT protein. Without enough functional CACT protein, long-chain fatty acids cannot be effectively transported into mitochondria, disrupting the normal process of fatty acid oxidation and energy production.

References

  1. Longo N, Amat di San Filippo C, Pasquali M. Disorders of carnitine transport and the carnitine cycle. American journal of medical genetics. Part C, Seminars in medical genetics. 2006. PMID: 16602102
  2. Korman SH, Pitt JJ, Boneh A. A novel SLC25A20 splicing mutation in patients of different ethnic origin with neonatally lethal carnitine-acylcarnitine translocase (CACT) deficiency. Molecular genetics and metabolism. 2006. PMID: 16919490
  3. Iacobazzi V, Pasquali M, Singh R. Response to therapy in carnitine/acylcarnitine translocase (CACT) deficiency due to a novel missense mutation. American journal of medical genetics. Part A. 2004. PMID: 15057979
  4. Galron D, Birk OS, Kazanovitz A. Carnitine-acylcarnitine translocase deficiency: identification of a novel molecular defect in a Bedouin patient. Journal of inherited metabolic disease. 2004. PMID: 15159657
  5. Rubio-Gozalbo ME, Bakker JA, Waterham HR. Carnitine-acylcarnitine translocase deficiency, clinical, biochemical and genetic aspects. Molecular aspects of medicine. 2004. PMID: 15363639
  6. Iacobazzi V, Invernizzi F, Baratta S. Molecular and functional analysis of SLC25A20 mutations causing carnitine-acylcarnitine translocase deficiency. Human mutation. 2004. PMID: 15365988
  7. Costa C, Costa JM, Slama A. Mutational spectrum and DNA-based prenatal diagnosis in carnitine-acylcarnitine translocase deficiency. Molecular genetics and metabolism. 2003. PMID: 12559850
  8. Ramsay RR, Gandour RD, van der Leij FR. Molecular enzymology of carnitine transfer and transport. Biochimica et biophysica acta. 2001. PMID: 11257506
Educational content. This page is not medical or genetic advice, is not individually reviewed by a clinician for each reader, and should not replace a consultation with a qualified healthcare professional or genetic counsellor. If you are considering genetic testing or acting on a test result, book a consultation.
Data sources Last updated 11 October 2026. Content compiled from HGNC · MedlinePlus Genetics · ClinGen · Genomics England PanelApp · NHS National Genomic Test Directory · ClinVar · UniProt · AlphaFold .