HRAS1 minisatellite alleles in colorectal carcinoma: relationship to microsatelite instability

To further evaluate sporadic colon carcinoma risk associated with rare HRAS1 VNTR alleles, the relationship with microsatellite instability and with HRAS1 VNTR instability.

The HRAS1 VNTR was genotyped in 121 tumors and normal samples from sporadic colon carcinoma patients (47 right and 74 left colon) and in 109 samples from healthy individuals. The HRAS1 alleles were identified using PCR and automatic fluorescent electrophoresis detection combined with MVR-PCR (Minisatellite Variant Repeat-Polymerase Chain Reaction). Microsatellite Instability (MI) was analysed with 10 microsatellite markers.

A relative risk of 3.04 (95% CI: 1.16-4.92) associated with rare alleles was obtained. No HRAS1 minisatellite instability was present in the tumors. Samples with MI were equally distributed between the common and rare HRAS1 allele groups, while the distribution of HRAS1 alleles in samples with MI was similar in right and left colorectal carcinoma.

Rare HRAS1 VNTR alleles are associated with colorectal carcinoma risk independent of the tumor location. MI is not likely to be involved in the same underlying defect that generates rare HRAS1 alleles in colorectal carcinoma.