In a comparison between the BM and primary tumors, the following genes were mutated in BM with increasing frequency: TP53, ATR, and APC (lung adenocarcinoma); ARID1A and FGF10 (lung small-cell); PIK3CG, NOTCH3, and TET2 (lung squamous); CDKN2A/B, PTEN, RUNX1T1, AXL, and FLT4 (melanoma); ERBB2, BRCA2, and AXL1 (breast carcinoma); and ATM, AR, CDKN2A/B, TERT, and TSC1 (renal clear-cell carcinoma). The gene discussed is CDKN2A; the disease is breast carcinoma.