Polymorphic insertion of additional repeat within an area of direct 8 bp tandem repeats in the 5 '-untranslated region of the p53R2 gene and cancer risk

p53R2 is a recently cloned gene that functions in p53-induced DNA repair. I n the 5'-untranslated region of the p53R2 gene two direct tandem 8 bp repea ts are located. Within the region of these 8 bp direct repeats we have dete cted the insertion of an additional repeat. In order to determine a possibl e association of this novel polymorphism with any cancer or population, we carried out genotyping of 843 European and Asian controls and patients with various cancer types. In addition, 26 cancer cell lines were included in t he study. No significant difference in polymorphic frequency could be demon strated for any of the cancer types, although the allelic frequency in mela noma patients was lower than in controls (chi (2) = 3.28; P = 0.07; OR = 0. 32; 95% CI 0.07-1.26). A significantly higher frequency of the polymorphism was detected in the compiled Caucasian individuals compared with Asians (c hi (2) = 9.19; P = 0.002; OR = 3.13; 95% CI 1.39-7.43). In one tumour cell line we observed two extra inserted copies of the 8 bp repeat. The function al effect of the insertion polymorphism on the p53R2 gene transcription rem ains to be determined.