EED is a component of the polycomb repressor complex 2 (PRC2). Missense and frameshift mutations have been described in T cell acute lymphoblastic leukemia and may be enriched in the early T cell precursor subtype of that disease(found in appromimately 5% of such cases). In addition, mutations of EED have been described in, overall, less than 5% of myeloid neoplasms including cases of CMML, AML and MDS. EED mutations tend to be exclusive of mutations in EZH2, another component of PRC2. Deletions of EED have also been described which are not detected by this assay.