High resolution analysis of the 5q-marker chromosome in refractory anemia

High resolution chromosome analysis of bone marrow cells was performed in 15 consecutive patients with refractory anemia and a deletion of the long arm of chromosome 5. The diagnosis was refractory anemia without excess of blasts (RAWEB) in 12 patients, and refractory anemia with excess of blasts (RAEB) in three patients. The 5q- anomaly was the only chromosomal change in 12 patients, whereas three had additional abberrations. The deletion was found to be interstitial and the breakpoints were identical in all cases: The proximal breakpoint was localized to subband 5q 13.3, and the distal breakpoint to 5q 33.1.