ABCB7: ATP Binding Cassette Subfamily B Member 7
Mitochondrial Iron-Sulfur Cluster Transporter and X-Linked Sideroblastic Anemia Gene
Gene Information Card
| Symbol | ABCB7 |
|---|---|
| Full Name | ATP Binding Cassette Subfamily B Member 7 |
| Gene Type | Protein coding |
| Chromosomal Location | Xq13.3 |
| NCBI Gene ID | 22 ncbi.nlm.nih.gov/gene/22 |
| Ensembl ID | ENSG00000131269 |
| UniProt ID | O75027 |
| OMIM ID | 300135 |
| HGNC ID | 48 |
| Aliases | ABC7, ASAT, Atm1p |
Description
ABCB7 encodes a mitochondrial ATP-binding cassette (ABC) transporter that exports iron-sulfur (Fe-S) clusters from the mitochondrial matrix to the cytosol. This protein is essential for cellular iron homeostasis, heme biosynthesis, and DNA repair. Mutations in ABCB7 cause X-linked sideroblastic anemia with ataxia (XLSA/A), a disorder characterized by mitochondrial iron accumulation and neurological deficits.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| X-linked sideroblastic anemia with ataxia (XLSA/A) | Loss-of-function mutations impair Fe-S cluster export, leading to mitochondrial iron overload, defective heme synthesis, and cerebellar ataxia. | ClinVar, OMIM |
| Friedreich ataxia modifier | ABCB7 polymorphisms may influence disease severity by modulating mitochondrial iron handling. | NCBI Gene, PubMed |
| Myelodysplastic syndromes | Somatic ABCB7 mutations have been reported in refractory anemia with ring sideroblasts (RARS), contributing to mitochondrial iron accumulation. | COSMIC, ClinVar |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Bone marrow | 12.5 | Medium |
| Cerebellum | 9.8 | Medium |
| Liver | 8.2 | Medium |
| Heart | 7.1 | Low |
| Skeletal muscle | 6.5 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| K562 (erythroleukemia) | 15.3 | High expression; relevant for erythroid differentiation |
| HepG2 (hepatocellular carcinoma) | 10.1 | Moderate expression |
| SH-SY5Y (neuroblastoma) | 8.7 | Moderate expression; relevant for neurological studies |
| HeLa (cervical carcinoma) | 6.4 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1305C>G (p.Tyr435*) | Nonsense | Rare | Loss of function; truncation of ABC transporter domain |
| c.1409G>A (p.Arg470Gln) | Missense | Rare | Impaired Fe-S cluster export; associated with XLSA/A |
| c.1580T>C (p.Ile527Thr) | Missense | Rare | Reduced protein stability; causes mild XLSA/A phenotype |
| c.703C>T (p.Arg235Trp) | Missense | Rare | Disrupts ATP binding; loss of function |
Mutation functional classification
Loss of Function (LOF)
Most ABCB7 mutations are loss-of-function, reducing Fe-S cluster export and causing mitochondrial iron accumulation.
Gain of Function (GOF)
No gain-of-function mutations have been reported.
Dominant Negative (DN)
No dominant-negative mutations have been described; X-linked inheritance pattern is recessive in females.
View complete mutation data：
Gene Ontology (GO)
| • ATP binding (GO:0005524) | • ATPase activity (GO:0016887) |
| • iron-sulfur cluster export (GO:1990204) | • mitochondrial inner membrane (GO:0005743) |
| • cellular iron ion homeostasis (GO:0006879) | • heme biosynthetic process (GO:0006783) |
Pathways
• Iron-sulfur cluster biogenesis (Reactome R-HSA-1369007)
• Mitochondrial iron-sulfur cluster export (Reactome R-HSA-1369008)
• Heme biosynthesis (Reactome R-HSA-189451)
Protein Summary
ABCB7 is a 753-amino acid mitochondrial inner membrane protein belonging to the ABC transporter superfamily. It forms a homodimer that uses ATP hydrolysis to transport Fe-S clusters from the mitochondrial matrix to the cytosol. The protein contains a transmembrane domain (TMD) and a nucleotide-binding domain (NBD). Defects in ABCB7 disrupt cytosolic Fe-S protein maturation, leading to mitochondrial iron overload, oxidative stress, and impaired erythropoiesis and neuronal function.
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