IDH1 and neoplasm: Since mass spectrometry measures of cystathionine in 1p/19q codeleted tumor tissues were not distinctly higher than those in 1p/19q noncodeleted tumors [25], as opposed to 2HG whose biopsy measures differed by 2–3 orders of magnitude between IDH‐mutant and IDH‐wildtype tumors [3], care should be taken when interpreting intermediate cystathionine estimates to predict the 1p/19q status in individual patients.