Inactivating mutations of PHF6 have been identified in 5-16% of pediatric and 19-40% of adult patients with T-ALL and ~25% of adults with T-lymphoblastic lymphoma (T-LBL) with some groups identifying an association with NOTCH1 mutations (67%-84.6% of PHF6 mutated/deleted T-ALL with NOTCH1 mutations versus 39.8% PHF6 WT) (4, 26–38). Here, NOTCH1 is linked to acute lymphoblastic leukemia.