JMML is associated with mutations in the RAS signaling pathway, with nearly 90% of patients harboring either germline or somatic mutations of protein tyrosine phosphatase non-receptor type 11 (PTPN11), Casitas B-lineage lymphoma (CBL), Neurofibromatosis type-1 (NF1), neuroblastoma rat sarcoma (NRAS), or Kirsten rat sarcoma (KRAS) [9]. The gene discussed is PTPN11; the disease is juvenile myelomonocytic leukemia.