We hypothesized that first and second-degree relatives of patients with an IDH1/2 mutated glioma and a germline rs55705857 G allele had higher risk for developing one or more of the following cancers in which IDH1/2 mutations have been found: glioma, prostate, colon, hepatic, lymphomas, biliary tumors, primary myelofibrosis, central chondrosarcoma, chrondroma/enchondroma, thyroid, acute lymphoblastic leukemia, and acute myelogenous leukemia [20–22]. The gene discussed is IDH1; the disease is primary myelofibrosis.