Accumulating mutations of p53 in colon tumor and hairy cell leukemia do not arise from methylation/deamination processes, but rather from nucleotide deletions and insertions.

Mutations of the p53 gene may alter the specific regulatory domains of the protein. We examined the conserved domains III, IV and V by SSCP using PCR primers covering exons 5, 6, 7 and 8 from hairy cell leukemia (HCL), polyps, colorectal and gastric carcinomas. A low rate of p53 mutations was detected in HCL and polyps. These mutations may predict the risk of malignant development. However, multiple mutations were a frequent occurrence in tumors. Sequence analysis of our samples did not demonstrate the high frequency of transition mutations (C-->T) that would be predicted if the major course of p53 mutations is deamination of 5-methylcytosine (5mC). Rather, most mutations were found to be single base insertions or deletions.