ANALYSIS OF THE P53 GENE IN MYELOID MALIGNANCIES ASSOCIATED WITH CHROMOSOMAL-ABNORMALITIES INVOLVING THE SHORT ARM OF CHROMOSOME-17

p53 protein is encoded by a tumor-suppressor gene located on the short arm of chromosome 17. We looked for mutations or rearrangements of th e p53 gene in five patients with acute transformation of a chronic mye loproliferative disorder and cytogenetic anomalies involving the short arm of chromosome 17. Two patients had a isochromosome i(17q); three more patients showed the presence of umbalanced translocations involvi ng chromosome 17. One of these patients had a single base pair deletio n, causing a frameshift mutation, in the exon 5 of the p53 gene. The k aryotype of this patient showed a translocation t(5;17)(q11;p11), with loss of a normal homolgue of both chromosomes 5 and 17. In all other cases the configuration of the p53 gene, as tested by PCR-SSCP analysi s of exons 5 to 9 and Southern blot, was normal. Our data suggest that mutations of the p53 gene occur in a minority of hemopoietic malignan cies characterized by monosomy for the short arm of chromosome 17. How ever, the umbalanced translocation t(5q;17p) could be a chromosomal ab normality specifically associated with loss of function of the p53 gen e.