Blood Journal
Leading the way in experimental and clinical research in hematology

The site of the breakpoint within the bcr is a prognostic factor in Philadelphia-positive CML patients [see comments]

  1. KI Mills,
  2. ED MacKenzie, and
  3. GD Birnie
  1. Beatson Institute for Cancer Research, Glasgow, Scotland.

Abstract

The Philadelphia (Ph1) chromosome, characteristic of chronic myelogenous leukemia (CML), arises from a reciprocal translocation between chromosomes 9 and 22. The site of the breakpoint on chromosome 22 is within a small region called the breakpoint cluster region (bcr). We have mapped the breakpoint within the bcr in peripheral blood leukocyte DNA from 22 Ph1-positive CML patients. No correlation between the site of the breakpoint and the clinical phase of the disease was found. However, a striking correlation between the site of the breakpoint and the length of time between presentation and onset of acute phase was observed: on average, patients with a 5′ break-point had a fourfold longer chronic phase (median, 203 weeks) than those with a 3′ breakpoint (median, 52 weeks).