A single nucleotide substitution at codon 31 (Ser/Arg) defines a polymorphism in a highly conserved region of the p53-inducible gene WAF1/CIP1.

The recently discovered WAF1/CTP1 gene is a mediator of p53 tumor suppressor activity. To analyse WAF1/ CIP1 for possible mutations, polymerase chain reaction (PCR) amplified cDNAs from several tumor cell lines were cloned and sequenced. A single point mutation which changes codon 31 from AGC to AGA (Ser to Arg) was found. This change resulted in the loss of a Bpu1102I and gain of an Esp3I restriction site, allowing for rapid screening of this mutation in human DNAs. Analysis of genomic DNAs from 50 randomly selected individuals revealed that this base pair substitution represents a polymorphism with an allelic frequency of 0.14. Transfection studies demonstrated that the expression of the Arg allele of WAF1/CIP1 was not associated with loss of tumor suppressor activity. Moreover, screening of 22 tumor DNA samples revealed no association between the tumor phenotype and the Arg allele of WAF1/CIP1 (two out of 22 tumor DNAs contained the Arg31 allele). This polymorphism will be a useful molecular marker in the analysis of loss of heterozygosity in human cancers, and further studies using a larger panel of tumors may reveal an association between this polymorphism and specific types of cancer.