This gene encodes a 190 kD nuclear phosphoprotein that maintains genomic stability and functions as a tumor suppressor. The BRCA1 protein forms part of the BRCA1-associated genome surveillance complex (BASC), interacting with tumor suppressors, DNA damage sensors, and RNA polymerase II. It plays a role in transcription, DNA repair, and recombination. Mutations in this gene account for 40% of inherited breast cancers and over 80% of inherited breast and ovarian cancers. Alternative splicing affects its subcellular localization and function. Various splice variants, some associated with disease, have been identified, though only some of their full-length forms have been characterized. A related pseudogene exists on chromosome 17.