Gene alterations involving the CRLF2 (Cytokine Receptor Like Factor 2) gene are frequently present in high-risk BCP-ALL patients [5] as well as T-ALL [6] and result in overexpression of CRLF2 subunit of the heterodimeric receptor of TSLP (thymic stromal lymphopoietin), known as TSLPR [7]. Here, CRLF2 is linked to acute lymphoblastic leukemia.