inclusion criteria: children aged 1 to 15 years old : with acute lymphoblastic leukemia undergoing chemotherapy (at least 2 weeks from the last injection of peg-asparaginase) or for whom the last chemotherapy is less than or equal to 12 months with acute myeloid leukemia within 12 months from the end of treatment healthy siblings aged 12 to 15 years old living in the same household than the child with al more than 50% of the time informed consent from parents patient affiliated to health insurance

inclusion criteria: children aged 1 to 15 years old : with acute lymphoblastic leukemia undergoing chemotherapy (at least 2 weeks from the last injection of peg-asparaginase) or for whom the last chemotherapy is less than or equal to 12 months with acute myeloid leukemia within 12 months from the end of treatment healthy siblings aged 12 to 15 years old living in the same household than the child with al more than 50% of the time informed consent from parents patient affiliated to health insurance