A novel 23-bp deletion in exon 5 of the p53 tumor suppressor gene.

We report a novel p53 deletion in a 63-year-old female with breast cancer. Mutation screening of DNA samples, obtained from tumor specimens from 98 individuals with breast cancer, by a combined polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis showed that the index case had a somatic mutation identified to be a 23-bp deletion in exon 5 of the p53 gene. This deletion would be expected to yield a truncated and functionally inactive p53 protein molecule, probably resulting in cell transformation. The existence of 6-bp palindromic-like sequences encompassing the deleted fragment suggests that the slipped mispairing mechanism is not involved in producing the deletion, which probably resulted from palindromic pairing during replication.