HRAS1 minisatellite alleles in colorectal carcinoma: Relationship to microsatelite instability

Objectives: To further evaluate sporadic colon carcinoma risk associated wi th rare HRAS1 VNTR alleles, the relationship with microsatellite instabilit y and with HRAS1 VNTR instability. Materials and Methods: The HRAS1 VNTR wa s genotyped in 121 tumors and normal samples from sporadic colon carcinoma patients (47 right and 74 left colon) and in 109 samples from healthy indiv iduals. The HRAS1 alleles were identified using PCR and automatic fluoresce nt electrophoresis detection combined with MVR-PCR (Minisatellite Variant R epeat-Polymerase Chain Reaction). Microsatellite Instability (MI) was analy sed with 10 microsatellite markers. Results: A relative risk of 3.04 (95% C P 1.16-4.92) associated with rare alleles was obtained. No HRAS1 minisatell ite instability was present in the tumors. Samples with MI were equally dis tributed between the common and rare HRAS1 allele groups, while the distrib ution of HRAS1 alleles in,samples with MI was similar in right and left col orectal carcinoma. Conclusion: Rare HRAS1 VNTR alleles are associated with colorectal carcinoma risk independent of the tumor location. MI is not like ly to be involved in the same underlying defect that generates rare HRAS1 a lleles in colorectal carcinoma.