BRCA1 and cancer: Interestingly, the BRCA1-specific chromosome 7 loss encompasses EGFR. The BRCA1-specific gain on chromosome 14 peaks at the T-cell receptor alpha (TCRα) locus and encompasses, among other cancer-related genes, poly(ADP-ribose) polymerase 2 (PARP2), and B-cell lymphoma 2 like 2 (BCL2L2).