Trisomy 8 in myelodysplasia and acute leukemia is constitutional in 15-20%of cases

The trisomy 8 found in malignancies may derive from a constitutional trisom y 8 mosaicism (CT8M), and in these cases the trisomy itself may be regarded as the first mutation in a multistep carcinogenetic process. To assess the frequency of CT8M in hematological dysplastic and neoplastic disorders wit h trisomy 8, an informative sample of 14 patients was collected. The data a scertained included chromosome analyses of fibroblast cultures and of PHA-s timulated blood cultures in patients with normal blood differential count, as well as possible CT8M clinical signs. One patient showed trisomy 8 in al l cell types analyzed and undoubtedly has a CT8M; a second patient consiste ntly showed trisomy 8 in PHA-stimulated blood cultures when no immature mye loid cells were present in blood and should be considered as having CT8M; a third patient, with Philadelphia-positive chronic myelocytic leukemia, was more difficult to interpret, but the possibility that she had CT8M is like ly. A few clinical signs of CT8M were also present in these three patients. Our data indicate that the frequency of CT8M in hematological dysplastic a nd neoplastic disorders with trisomy 8 is approximately 15-20%. (C) 2002 Wi ley-Liss, Inc.