Colorectal cancer risk is not associated with increased levels of homozygosity in Saudi Arabia

Purpose:Runs of homozygosity (ROHs) represent a measure of the extent of autozygosity and are correlated with the extent of inbreeding. Recently, it has been suggested that ROHs may contribute to the risk of colorectal cancer (CRC). The high rate of consanguinity and CRC in the Saudi population prompted us to test the role of autozygosity in the CRC risk.Methods:We compared 48 Saudi CRC patients to 100 ethnically matched controls, processed on the Affymetrix 250K StyI SNP GeneChip platform and analyzed using the plink package.Results:We could find no evidence of a significant relationship between autozygosity and CRC risk.Conclusion:The negative results in our study add additional significance to what has been previously reported in literature, as this is the first study to address these questions in an inbred population. Our subgroup analysis of patients with microsatellite unstable-positive tumors as compared with other groups did not significantly change our results. Although these results do not rule out the presence of recessively acting CRC-predisposing genes in a small percentage of patients, which our relatively small sample size could not capture, they suggest that such genes are unlikely to account for the disturbingly high incidence of CRC in our consanguineous population.Genet Med advance online publication 5 April 2012.