However, deletion of 9p21.3 is considered an unfavorable chromosomal aberration in renal cell carcinoma.[27] There are at least 3 TSGs at 9p21.3: CDKN2A, CDKN2B, and MTAP, and deletion of 9p21.3 may predispose an individual to melanoma, neural system tumors, hematologic malignancies, astrocytoma, breast cancer, and chordoma.[28–30] All 3 TSGs were included in the lost segment in the current patient, suggesting that the somatic microdeletion of 9p21.3 may have contributed to the occurrence of malignancy in this case. The gene discussed is CDKN2B; the disease is breast cancer.