A team from Salt Lake City, Utah and Oakland, California, USA assessed whether the B1822V variant of the adenomatous polyposis coli (APC) gene is associated with colon cancer. They also investigated whether its association is influenced by other genetic or environmental factors.
The B1822V variant is produced by an aspartate to valine change at codon 1822 in the APC gene, and previous studies have reported an allele frequency of 10%.
Data collected from 1,585 incident cases of colon cancer and 1,945 age- and sex-matched population-based controls were used in the study.
|Homozygous APC variant genotype and low-fat diet may confer a lower risk of colon cancer.|
The frequency of the valine/valine allele at codon 1,822 was found to be 22.8% in the population.
In the control population, 61.5% were homozygote wild type, 33.3% were heterozygotes, and 5.2% were homozygote variant.
Cases were slightly less likely to have the homozygous variant APC genotype than were controls (odds ratio [OR], 0.8). For those diagnosed after age 65, the homozygous APC variant was associated with reduced risk of colon cancer (OR, 0.6).
Assessment of the homozygous APC variant with dietary, genetic, and environmental factors showed that individuals with this genotype were at lower risk if they consumed a low-fat diet (OR, 0.2) relative to those who were homozygous wild type and ate a high-fat diet.
Dr Martha L. Slattery, of the University of Utah, concluded on behalf of the group, "These results suggest that the codon 1822 variant of the APC gene may have functional significance.
"Individuals who have the valine/valine variant of this gene may be at reduced risk of colon cancer if they eat a low-fat diet."