Somatic mutations in PTPN11 are found in 35% of sporadic juvenile myelomonocytic leukaemia (JMML) [12] and at a lower frequency in childhood myelodyplastic syndrome, B-ALL, and acute myologenous leukaemia (AML), as well as adult AML [13,14,15]. The gene discussed is PTPN11; the disease is acute lymphoblastic leukemia.