Isochromosome (17q) in Philadelphia chromosome (Ph1)-negative juvenile chronic myelocytic leukemia.

A dicentric isochromosome of the long arm of one chromosome #17 was the only abnormality present in a 12-year-old boy with Philadelphia chromosome (Ph1)-negative juvenile chronic myelocytic leukemia. This association does not seem to have been reported in the literature. It is postulated that the finding of an isochromosome (17q) may also have a negative prognostic value in the Ph1-negative type of chronic myelogenous leukemia.