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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed January 2008

What is the official name of the ACAT1 gene?

The official name of this gene is “acetyl-CoA acetyltransferase 1.”

ACAT1 is the gene's official symbol. The ACAT1 gene is also known by other names, listed below.

What is the normal function of the ACAT1 gene?

The ACAT1 gene provides instructions for making an enzyme that is found in the energy-producing centers within cells (mitochondria). This enzyme plays an essential role in breaking down proteins and fats from the diet. Specifically, it helps process isoleucine, an amino acid that is a building block of many proteins. This enzyme is also involved in processing ketones, which are molecules that are produced when fats are broken down in the body.

During the breakdown of proteins, the ACAT1 enzyme is responsible for the last step in processing isoleucine. It converts a molecule called 2-methyl-acetoacetyl-CoA into two smaller molecules, propionyl-CoA and acetyl-CoA, that can be used to produce energy.

The ACAT1 enzyme carries out the last step in ketone breakdown (ketolysis) during the processing of fats. The enzyme converts a molecule called acetoacetyl-CoA into two molecules of acetyl-CoA, which can be used to produce energy. In the liver, the enzyme also carries out this chemical reaction in reverse, which is the first step in building new ketones (ketogenesis).

How are changes in the ACAT1 gene related to health conditions?

beta-ketothiolase deficiency - caused by mutations in the ACAT1 gene

More than 40 mutations in the ACAT1 gene have been identified in people with beta-ketothiolase deficiency. Some of these genetic changes disrupt the normal function of the enzyme, while other mutations prevent cells from producing any functional enzyme.

A shortage of the ACAT1 enzyme prevents the body from processing proteins and fats properly. As a result, chemical byproducts called organic acids can build up to toxic levels in the blood. These substances cause the blood to become too acidic (ketoacidosis), which can damage the body's tissues and organs, particularly in the nervous system. This damage leads to episodes of vomiting, dehydration, and other health problems associated with beta-ketothiolase deficiency.

Where is the ACAT1 gene located?

Cytogenetic Location: 11q22.3

Molecular Location on chromosome 11: base pairs 108,121,531 to 108,148,168

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The ACAT1 gene is located on the long (q) arm of chromosome 11 at position 22.3.

The ACAT1 gene is located on the long (q) arm of chromosome 11 at position 22.3.

More precisely, the ACAT1 gene is located from base pair 108,121,531 to base pair 108,148,168 on chromosome 11.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about ACAT1?

You and your healthcare professional may find the following resources about ACAT1 helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the ACAT1 gene or gene products?

  • ACAT
  • acetoacetyl Coenzyme A thiolase
  • acetyl-Coenzyme A acetyltransferase 1
  • acetyl-Coenzyme A acetyltransferase 1 (acetoacetyl Coenzyme A thiolase)
  • acetyl-Coenzyme A acetyltransferase 1 precursor
  • MAT
  • T2
  • THIL

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding ACAT1?

acids ; amino acid ; breakdown ; CoA ; coenzyme A ; deficiency ; dehydration ; enzyme ; gene ; isoleucine ; ketogenesis ; ketolysis ; ketone ; ketone body ; methyl ; mitochondria ; molecule ; nervous system ; precursor ; toxic

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Fukao T, Matsuo N, Zhang GX, Urasawa R, Kubo T, Kohno Y, Kondo N. Single base substitutions at the initiator codon in the mitochondrial acetoacetyl-CoA thiolase (ACAT1/T2) gene result in production of varying amounts of wild-type T2 polypeptide. Hum Mutat. 2003 Jun;21(6):587-92. (
  • Fukao T, Scriver CR, Kondo N; t2 Collaborative Working Group. The clinical phenotype and outcome of mitochondrial acetoacetyl-CoA thiolase deficiency (beta-ketothiolase or T2 deficiency) in 26 enzymatically proved and mutation-defined patients. Mol Genet Metab. 2001 Feb;72(2):109-14. (
  • Fukao T, Yamaguchi S, Orii T, Hashimoto T. Molecular basis of beta-ketothiolase deficiency: mutations and polymorphisms in the human mitochondrial acetoacetyl-coenzyme A thiolase gene. Hum Mutat. 1995;5(2):113-20. Review. (
  • Kano M, Fukao T, Yamaguchi S, Orii T, Osumi T, Hashimoto T. Structure and expression of the human mitochondrial acetoacetyl-CoA thiolase-encoding gene. Gene. 1991 Dec 30;109(2):285-90. (
  • Korman SH. Inborn errors of isoleucine degradation: a review. Mol Genet Metab. 2006 Dec;89(4):289-99. Epub 2006 Sep 6. Review. (
  • NCBI Gene (
  • Zhang GX, Fukao T, Rolland MO, Zabot MT, Renom G, Touma E, Kondo M, Matsuo N, Kondo N. Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency: T2-deficient patients with "mild" mutation(s) were previously misinterpreted as normal by the coupled assay with tiglyl-CoA. Pediatr Res. 2004 Jul;56(1):60-4. Epub 2004 May 5. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: January 2008
Published: February 8, 2016