Consistent with this hypothesis, BRCA1 mRNA expression levels have been shown to positively correlate with ESR1 mRNA levels in patients with sporadic BC, while reduced BRCA1 levels or activation, which can occur in sporadic BCs during tumor progression, or as a result of treatment-induced modifications of tumor biology, could directly impact ERα loss [79]. The gene discussed is BRCA1; the disease is neoplasm.