BRAF is an oncogene mutated in about half of melanomas (BRAF‐V600E mutation in most cases) and in other tumor entities as well (thyroid papillary carcinoma, colorectal carcinoma, hairy cell leukemia, Langerhans cell histiocytosis) (Andrulis, Penzel, Weichert, von Deimling, & Capper, 2012; Garnett & Marais, 2004; Ida et al., 2013; Long et al., 2013; Michaloglou, Vredeveld, Mooi, & Peeper, 2008; Rahman, Salajegheh, Smith, & Lam, 2013; Ritterhouse & Barletta, 2015; Sahm et al., 2012; Schindler et al., 2011). The gene discussed is BRAF; the disease is hairy cell leukemia.