In common with deletion of CDKN2A/B, CFA 13 gain is among the most highly recurrent CNAs across the spectrum of spontaneously established tumor cell lines and naturally occurring canine cancers, including appendicular osteosarcoma, histiocytic sarcoma, glioma, non-Hodgkin’s lymphoma, mucosal melanoma, and urothelial carcinoma (Thomas et al. 2009, 2011; Angstadt et al. 2011; Hedan et al. 2011; Seiser et al. 2013; Poorman et al. 2015; Shapiro et al. 2015). The gene discussed is CDKN2A; the disease is histiocytic sarcoma.