A patient with hormone-receptor (HR+) breast carcinoma exhibited mutant IDH1 R132L within the tumor tissue and cells in lymph nodes, which corresponded to an elevated 2HG concentration in urine (22 ng/mL vs. 1.7 ng/mL in healthy controls) and serum (1979 ng/mL vs. 105 ng/mL in healthy controls) (50). The gene discussed is IDH1; the disease is breast carcinoma.