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Genetics Home Reference: your guide to understanding genetic conditions
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APOA1

Reviewed November 2012

What is the official name of the APOA1 gene?

The official name of this gene is “apolipoprotein A-I.”

APOA1 is the gene's official symbol. The APOA1 gene is also known by other names, listed below.

What is the normal function of the APOA1 gene?

The APOA1 gene provides instructions for making a protein called apolipoprotein A-I (apoA-I). ApoA-I is a component of high-density lipoprotein (HDL). HDL is a molecule that transports cholesterol and certain fats called phospholipids through the bloodstream from the body's tissues to the liver. Once in the liver, cholesterol and phospholipids are redistributed to other tissues or removed from the body.

ApoA-I attaches to cell membranes and promotes the movement of cholesterol and phospholipids from inside the cell to the outer surface. Once outside the cell, these substances combine with apoA-I to form HDL. ApoA-I also triggers a reaction called cholesterol esterification that converts cholesterol to a form that can be fully integrated into HDL and transported through the bloodstream.

HDL is often referred to as "good cholesterol" because high levels of this substance reduce the chances of developing heart and blood vessel (cardiovascular) disease. The process of removing excess cholesterol from cells is extremely important for balancing cholesterol levels and maintaining cardiovascular health.

How are changes in the APOA1 gene related to health conditions?

familial HDL deficiency - caused by mutations in the APOA1 gene

Mutations in the APOA1 gene cause familial HDL deficiency, an inherited condition characterized by low levels of HDL in the blood and an elevated risk for early-onset cardiovascular disease, which often occurs before age 50. These mutations lead to an altered apoA-I protein. Some versions of the altered protein are less able to promote the removal of cholesterol and phospholipids from cells, which decreases the amount of these substances available to form HDL. Other versions of the altered protein are less able to stimulate cholesterol esterification, which means cholesterol cannot be integrated into HDL particles. Both types of mutation result in low HDL levels. A shortage (deficiency) of HDL is believed to increase the risk of cardiovascular disease.

other disorders - caused by mutations in the APOA1 gene

Mutations in the APOA1 gene can also cause a condition called familial visceral amyloidosis, which is characterized by an abnormal accumulation of proteins (amyloidosis) in internal organs (viscera). The mutations that cause this condition alter the apoA-I protein. Abnormal apoA-I proteins stick together to form amyloid deposits that impair the function of the affected organs. The liver, kidneys, and heart are commonly affected by amyloidosis. Depending on the organs involved, the signs and symptoms of the condition vary. Affected individuals can have an enlarged liver (hepatomegaly), chronic kidney disease, or a form of heart disease called cardiomyopathy. However, in some people, the condition is very mild and causes no apparent signs or symptoms.

Where is the APOA1 gene located?

Cytogenetic Location: 11q23-q24

Molecular Location on chromosome 11: base pairs 116,835,750 to 116,837,621

The APOA1 gene is located on the long (q) arm of chromosome 11 between positions 23 and 24.

The APOA1 gene is located on the long (q) arm of chromosome 11 between positions 23 and 24.

More precisely, the APOA1 gene is located from base pair 116,835,750 to base pair 116,837,621 on chromosome 11.

See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.

Where can I find additional information about APOA1?

You and your healthcare professional may find the following resources about APOA1 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 APOA1 gene or gene products?

  • APOA1_HUMAN
  • apoA-I
  • apo-AI

See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.

What glossary definitions help with understanding APOA1?

amyloid ; amyloidosis ; apolipoprotein ; apolipoprotein A-I ; cardiomyopathy ; cardiovascular ; cell ; cholesterol ; chronic ; deficiency ; familial ; gene ; HDL ; inherited ; kidney ; lipoprotein ; molecule ; mutation ; phospholipids ; protein ; viscera

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://ghr.nlm.nih.gov/glossary).

References

  • OMIM: APOLIPOPROTEIN A-I (http://omim.org/entry/107680)
  • Batal R, Tremblay M, Krimbou L, Mamer O, Davignon J, Genest J Jr, Cohn JS. Familial HDL deficiency characterized by hypercatabolism of mature apoA-I but not proapoA-I. Arterioscler Thromb Vasc Biol. 1998 Apr;18(4):655-64. (http://www.ncbi.nlm.nih.gov/pubmed/9555873?dopt=Abstract)
  • Chambenoit O, Hamon Y, Marguet D, Rigneault H, Rosseneu M, Chimini G. Specific docking of apolipoprotein A-I at the cell surface requires a functional ABCA1 transporter. J Biol Chem. 2001 Mar 30;276(13):9955-60. Epub 2001 Jan 9. (http://www.ncbi.nlm.nih.gov/pubmed/11150301?dopt=Abstract)
  • Chroni A, Liu T, Gorshkova I, Kan HY, Uehara Y, Von Eckardstein A, Zannis VI. The central helices of ApoA-I can promote ATP-binding cassette transporter A1 (ABCA1)-mediated lipid efflux. Amino acid residues 220-231 of the wild-type ApoA-I are required for lipid efflux in vitro and high density lipoprotein formation in vivo. J Biol Chem. 2003 Feb 28;278(9):6719-30. Epub 2002 Dec 17. (http://www.ncbi.nlm.nih.gov/pubmed/12488454?dopt=Abstract)
  • Daum U, Leren TP, Langer C, Chirazi A, Cullen P, Pritchard PH, Assmann G, von Eckardstein A. Multiple dysfunctions of two apolipoprotein A-I variants, apoA-I(R160L)Oslo and apoA-I(P165R), that are associated with hypoalphalipoproteinemia in heterozygous carriers. J Lipid Res. 1999 Mar;40(3):486-94. (http://www.ncbi.nlm.nih.gov/pubmed/10064737?dopt=Abstract)
  • Eriksson M, Schönland S, Yumlu S, Hegenbart U, von Hutten H, Gioeva Z, Lohse P, Büttner J, Schmidt H, Röcken C. Hereditary apolipoprotein AI-associated amyloidosis in surgical pathology specimens: identification of three novel mutations in the APOA1 gene. J Mol Diagn. 2009 May;11(3):257-62. doi: 10.2353/jmoldx.2009.080161. Epub 2009 Mar 26. (http://www.ncbi.nlm.nih.gov/pubmed/19324996?dopt=Abstract)
  • NCBI Gene (http://www.ncbi.nlm.nih.gov/gene/335)
  • Oram JF. HDL apolipoproteins and ABCA1: partners in the removal of excess cellular cholesterol. Arterioscler Thromb Vasc Biol. 2003 May 1;23(5):720-7. Epub 2003 Jan 9. Review. (http://www.ncbi.nlm.nih.gov/pubmed/12615680?dopt=Abstract)
  • Rowczenio D, Dogan A, Theis JD, Vrana JA, Lachmann HJ, Wechalekar AD, Gilbertson JA, Hunt T, Gibbs SD, Sattianayagam PT, Pinney JH, Hawkins PN, Gillmore JD. Amyloidogenicity and clinical phenotype associated with five novel mutations in apolipoprotein A-I. Am J Pathol. 2011 Oct;179(4):1978-87. doi: 10.1016/j.ajpath.2011.06.024. Epub 2011 Aug 5. (http://www.ncbi.nlm.nih.gov/pubmed/21820994?dopt=Abstract)

 

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? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.

 
Reviewed: November 2012
Published: January 27, 2015