Molecular analysis of structural chromosome changes affecting chromosome band 11q23

Involvement of the ets-1 proto-oncogene located at chromosome band 11q23 was studied in six tumors and in a congenital chromosome abnormality affecting the 11q23 region, in order to determine whether the breakpoint of these rearrangements was identical at the molecular level. In multiple restriction digestions a 5.4 kb EcoRI genomic probe of the c-ets-1 gene did not detect rearrangements in any of these samples. Thus, in these tumors the break in DNA was not within the domain of c-ets-1 recognized by this probe. However, after digestion with XbaI enzyme the probe detected a 2.4 kb polymorphic allele in placental DNA. One tumor DNA sample showed homozygosity for this polymorphic allele. In order to determine the frequency of this polymorphic allele, DNA from 50 additional tumors and from the blood of nine healthy donors was analyzed. DNA from one tumor showed homozygosity for the polymorphic allele. In the 67 DNA samples studied, 17.9 per cent were heterozygous for the polymorphic site and 3 per cent were homozygous for the polymorphic site. Thus, the overall frequency of the polymorphic allele in these samples was 0.111.