CCND1 copy gain occurs in about 15 -20% of breast tumors and its mRNA and protein was found overexpressed inapproximately 50% of breast cancers, suggesting that other mechanisms than CNAs areinvolved in its expression regulation (Buckleyet al., 1993; Gillettet al., 1994; Maiaet al., 2015). The gene discussed is CCND1; the disease is breast cancer.