Azacitidine and Homoharringtonine in JMML

Inclusion Criteria: * Newly diagnosed JMML, with PB and BM confirming diagnosis prior to informed consent signature, with one of the following: 1. somatic mutation in PTPN11 2. somatic mutation in KRAS 3. somatic mutation in NRAS and HbF % \> 5x normal value for age 4. clinical diagnosis of neurofibromatosis Type 1. Exclusion Criteria: * 1\. Any condition that would prevent the subject from participating in the study. 2\. Any condition including the presence of laboratory abnormalities, which places the subject at unacceptable risk if participated in the study. 3\. Any condition that confounds the ability to interpret data from the study.