Missing Y chromosome in juvenile chronic myelogenous leukemia

A child with Ph1-negative juvenile chronic myelogenous leukemia (CML) is presented. The only chromosomal abnormality in hematopoietic tissues consisted of an absent Y chromosome. While a missing Y chromosome in adult patients with CML may be associated with a better prognosis, the clinical course in our patient was as malignant as that usually observed in other children with Ph1-negative juvenile CML.