By performing an NGS panel that was designed for myeloid neoplasias, Wand et al. found that, in 51 idiopathic HES individuals, the most frequently mutated genes are ASXL transcriptional regulator 1 (ASXL1) (43%), Tet methylcytosine dioxygenase 2 (TET2) (36%), Enhancer of zeste homolog 2(EZH2) (29%), SET binding protein 1 (SETBP1) (22%), Casitas B-lineage Lymphoma (CBL) (14%), and Notch homolog 1, translocation-associated (NOTCH1) (14%) [104]. Here, TET2 is linked to hypereosinophilic syndrome.