[Monosomy 5 (-5), deletion of the long arm of chromosome 6 (6q) and acquisition of a chromosome 21 (+21) in a boy with acute leukemia at high-risk].

The chromosomal abnormality 6q-, associated with acute lymphatic leukemia, is often found both in T cell form and in non T non B cell forms. The absence of chromosome -5, frequently associated with acute non-lymphatic leukemia of the adult, has been rarely found in the acute non-lymphatic leukemia of the child. Trisomy of chromosome 21 is the most associated with acute non-lymphatic leukemia of the adult, has been rarely found in the acute non-lymphatic leukemia of the child. Trisomy of chromosome 21 is the most frequent alteration found in children and adult with acute lymphatic leukemia. In a child (aged 7) affected by acute lymphatic leukemia the karyotype analysis showed simultaneously the presence of the 3 above mentioned abnormalities. It will be important to evaluate later on how the association of monosomy 5 with the deletion of chromosome's 6 long arm and with an acquired chromosome 21, the last two being indexes of a favourable prognosis, can influence the clinical course of the disease.