Childhood monosomy 7 syndrome.

In recent years, chromosomal aberrations in various hematologic disorders have raised a great deal of interest. In fact, several nonrandom chromosomal abnormalities are now recognized to be responsible for a specific type of dyshemopoiesis while others are closely associated with characteristic hematologic features. Monosomy C, later shown to be monosomy 7 by different banding methods, has been described in children in relation to a peculiar myeloproliferative disorder. Retrospective analysis of early cases published in the literature and a recent observation that we wish to report suggest that the most consistent phenotypic expression of monosomy 7 is an increased susceptibility to bacterial infections related to a preleukemic dyshemopoiesis. Acute nonlymphocytic leukemia is the terminal event of this peculiar preleukemic syndrome, and thus suggests that monosomy 7 involves a stem cell already committed to myeloid differentiation.