A FACTOR ENCODED BY 7Q31 SUPPRESSES EXPANSION OF THE 7Q- CLONE AND DELAYS CYTOGENETIC PROGRESSION

Deletion of part of chromosome 7q (7q-) is a consistent aberration in human acute leukemias and myelodysplasias, especially in patients with a history of genotoxic exposure. The deletion is usually associated with a short survival. Loss of a number of different 7q segments has been described, but still it is not known whether different deletions imply differences in survival. We have investigated the possible importance of loss of different segments in 77 7q- patients studied with high-resolution banding. Thirty-six were examined in our laboratory and 41 were published cases. We found that when the 7q- marker contained the 7q31 bond, the 7q- clone was smaller than when the band had been lost (p = 0.011), and the patients survived longer (p = 0.004). Further, karyotypes with complex aberrations were less frequent (p = 0.012). These results indicate that genetic information in 7q31 delays cytogenetic and clinical progression of myeloid disease with 7q-. Our results do not tell, however, whether this is due to direct tumor suppressor activity of a 7q31 gene or due to a more indirect effect.