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• Secondary AML caused by topoisomerase II inhibitors (e.g. etoposide) has a latency of 1-3 years and is of FAB type M4/M5 with a characteristic MLL gene mutation.

• Secondary AML caused by alkylating agents (e.g. cyclophosphamide) has a latency of 4-6 years, a myelodysplastic phase and loss or deletions of chromosomes 5, 7 or both.

• Down syndrome children are 20 times more likely to develop leukaemia than normal children; infants are more likely to develop M7 AML, older Down children develop ALL.

• Other conditions predisposing to AML in children are Fanconi's anaemia and Bloom's syndrome (ffl p457), dyskeratosis congenita, Kostmann's syndrome and Shwachman-Diamond syndrome (ffl p459), DiamondBlackfan anaemia (ffl p452), and neurofibromatosis.

Apart from the specific changes in secondary AMLs (see above), clonal chromosome abnormalities are found in blasts from ~90% of those with de novo disease. Two-thirds of these are non-random, and many are associated with characteristic clinical and biological features.

Commonest genetic mutations in childhood AML

Abnormality Involved genes t(8;21) ETO; AML1

FAB type

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