RESUMO
Down Syndrome (DS) is associated with an increased incidence of malignancies, especially leukaemias. We came across 8 DS children presenting with malignancies and having trisomy 21 as the sole cytogenetic abnormality. Of these 8 DS cases, 4 presented with acute lymphocytic leukaemia, 2 with acute myeloid leukaemia and one case each with Hodgkin's disease and Wilms' tumour. There are contradictory reports regarding the distribution of myeloid versus lymphoid malignancies in DS children and their response to therapy. The exact mechanism by which patients with DS are predisposed to develop malignancies is unclear. However, presence of the extra chromosome no. 21 is presumed to disrupt the genetic balance which increases generalized susceptibility to genetic and environmental trauma. Furthermore, an increased methotrexate toxicity observed in these patients should also be taken into consideration in designing treatment for DS children with malignancies.