IDH1 and central nervous system cancer: For example, in grade 2–3 gliomas, the T2-FLAIR mismatch sign can predict an IDH [isocitrate dehydrogenase]-mutant astrocytoma without 1p/19q-codeletion (combined loss of the short arm of chromosome 1 and long arm of chromosome 19) with specificity close to 100% and high inter-observer agreement[5-10], albeit with a moderate sensitivity of about 42% on pooled analysis [8].