Patients with MEN4 express MEN1-like milder phenotypes due to CDKN1B germline variants and, less frequently, other non-endocrine neoplasms such as breast cancer, prostate cancer, colon cancer, papillary thyroid carcinoma, angiomyolipoma, and meningioma, although only approximately 100 cases have been reported to date (10, 11). The gene discussed is CDKN1B; the disease is breast carcinoma.