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Normal Function
The ABCB7 gene provides instructions for making a protein known as an ATP-binding cassette (ABC) transporter. ABC transporter proteins carry many types of molecules across cell membranes.
The ABCB7 protein is located in the inner membrane of cell structures called mitochondria. Mitochondria are the energy-producing centers of cells, but they are also involved in a variety of cellular activities, including chemical signaling and the regulation of cell growth and division.
In the mitochondria of developing red blood cells (erythroblasts), the ABCB7 protein plays a critical role in the production of heme. Heme contains iron and is required for cell processes such as energy production and molecule transport. Most importantly, heme is a component of hemoglobin, the protein that carries oxygen in the blood.
The ABCB7 protein is also involved in the formation of clusters of iron and sulfur atoms (Fe-S clusters). The ABCB7 protein transports a sulfur-containing compound from mitochondria to the surrounding cellular fluid (cytosol), where Fe-S clusters are formed. These clusters are then incorporated into proteins. Proteins that contain Fe-S clusters are necessary for many functions, including the maintenance of cells and genes.
The ABCB7 protein appears to play a key role in maintaining an appropriate balance of iron (iron homeostasis) in erythroblasts.
Health Conditions Related to Genetic Changes
X-linked sideroblastic anemia and ataxia
A few variants (also called mutations) in the ABCB7 gene have been identified in people with X-linked sideroblastic anemia with ataxia. This condition is a rare disorder that is characterized by a shortage of healthy red blood cells (anemia) and a movement disorder called ataxia that causes problems with balance and coordination.
The ABCB7 gene variants slightly alter the structure of the ACBC7 protein by causing one protein building block (amino acid) to be substituted for another. These changes prevent the protein from performing its usual roles in heme production and iron homeostasis. Anemia occurs when heme cannot be produced normally and red blood cells cannot make enough hemoglobin. Without enough heme and proteins that contain Fe-S clusters, cells cannot function properly, resulting in ataxia and the other movement problems seen in people with X-linked sideroblastic anemia with ataxia.
More About This Health ConditionOther Names for This Gene
- ABCB7_HUMAN
- ATP-binding cassette 7
Additional Information & Resources
Tests Listed in the Genetic Testing Registry
Scientific Articles on PubMed
Catalog of Genes and Diseases from OMIM
References
- Allikmets R, Raskind WH, Hutchinson A, Schueck ND, Dean M, Koeller DM. Mutation of a putative mitochondrial iron transporter gene (ABC7) in X-linked sideroblastic anemia and ataxia (XLSA/A). Hum Mol Genet. 1999 May;8(5):743-9. doi: 10.1093/hmg/8.5.743. Citation on PubMed
- Bekri S, Kispal G, Lange H, Fitzsimons E, Tolmie J, Lill R, Bishop DF. Human ABC7 transporter: gene structure and mutation causing X-linked sideroblastic anemia with ataxia with disruption of cytosolic iron-sulfur protein maturation. Blood. 2000 Nov 1;96(9):3256-64. Citation on PubMed
- Chiabrando D, Bertino F, Tolosano E. Hereditary Ataxia: A Focus on Heme Metabolism and Fe-S Cluster Biogenesis. Int J Mol Sci. 2020 May 26;21(11):3760. doi: 10.3390/ijms21113760. Citation on PubMed
- Nie Z, Yan Q, Shen Y, Yang X. Expression, purification and microscopic characterization of human ATP-binding cassette sub-family B member 7 protein. Protein Expr Purif. 2021 Jul;183:105860. doi: 10.1016/j.pep.2021.105860. Epub 2021 Mar 6. Citation on PubMed
- Pondarre C, Antiochos BB, Campagna DR, Clarke SL, Greer EL, Deck KM, McDonald A, Han AP, Medlock A, Kutok JL, Anderson SA, Eisenstein RS, Fleming MD. The mitochondrial ATP-binding cassette transporter Abcb7 is essential in mice and participates in cytosolic iron-sulfur cluster biogenesis. Hum Mol Genet. 2006 Mar 15;15(6):953-64. doi: 10.1093/hmg/ddl012. Epub 2006 Feb 8. Citation on PubMed
- Pondarre C, Campagna DR, Antiochos B, Sikorski L, Mulhern H, Fleming MD. Abcb7, the gene responsible for X-linked sideroblastic anemia with ataxia, is essential for hematopoiesis. Blood. 2007 Apr 15;109(8):3567-9. doi: 10.1182/blood-2006-04-015768. Epub 2006 Dec 27. Citation on PubMed or Free article on PubMed Central
- Shimada Y, Okuno S, Kawai A, Shinomiya H, Saito A, Suzuki M, Omori Y, Nishino N, Kanemoto N, Fujiwara T, Horie M, Takahashi E. Cloning and chromosomal mapping of a novel ABC transporter gene (hABC7), a candidate for X-linked sideroblastic anemia with spinocerebellar ataxia. J Hum Genet. 1998;43(2):115-22. doi: 10.1007/s100380050051. Citation on PubMed
- Yan Q, Shen Y, Yang X. Cryo-EM structure of AMP-PNP-bound human mitochondrial ATP-binding cassette transporter ABCB7. J Struct Biol. 2022 Mar;214(1):107832. doi: 10.1016/j.jsb.2022.107832. Epub 2022 Jan 15. Citation on PubMed
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