This gene encodes a 190 kD nuclear phosphoprotein that maintains genomic stability and acts as a tumor suppressor. The BRCA1 protein forms a complex with other tumor suppressors and DNA damage sensors, known as the BRCA1-associated genome surveillance complex (BASC). It interacts with RNA polymerase II and histone deacetylase complexes, playing a role in transcription, DNA repair, and recombination. Mutations in this gene cause about 40% of inherited breast cancers and over 80% of inherited breast and ovarian cancers. Alternative splicing modulates its subcellular localization and function. Several alternatively spliced variants, some associated with diseases, have been identified, though the full-length variants are not completely described. A related pseudogene is located on chromosome 17.