In T-ALL, IL7R mutations are substantially enriched in immature T-ALL cases and in cases aberrantly expressing TLX1, TLX3 or HOXA, and also in B-ALL IL7R alterations are found in specific subtypes, including Ph-like, CRLF2-rearranged, iAMP21-positive, IKZF1 mutant or PAX5 mutant B-ALL [57]. The gene discussed is CRLF2; the disease is precursor B-cell acute lymphoblastic leukemia.