A 29-year-old woman presents with weakness, fatigue, easy bruising, and nosebleeds. Analysis of her blood reveals a reciprocal translocation between chromosomes 22 and 9, and low leukocyte alkaline phosphatase levels. These findings confirm a diagnosis of which of the following?

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The reciprocal translocation between chromosomes 22 and 9 is known as the Philadelphia chromosome, which is characteristic of chronic myelogenous leukemia (CML). Low leukocyte alkaline phosphatase levels are also associated with CML. Ninety percent of individuals with chronic myelogenous leukemia have an acquired Philadelphia chromosome abnormality consisting of a translocation between chromosomes 22 and 9. The translocation places the proto-oncogene ABL from chromosome 9 next to the breakpoint cluster region (BCR) on chromosome 22. The unique gene sequence BCR-ABL confers a growth advantage with subsequent clonal expansion.

A 29-Year-Old Woman Presents with Weakness, Fatigue, Easy Bruising, and Nosebleeds