A recently discovered, but not yet understood, section of chromosome 8, called 8q24, may contain at least five distinct regions that are associated with different cancers, according to a study in the June 24 issue of the Journal of the National Cancer Institute.
Recent genome-wide studies suggested that genetic alterations in the 8q24 region are associated with a risk of prostate, colorectal and breast cancer. The region does not contain any known genes and is referred to as a gene desert, but researchers have mapped it using single nucleotide polymorphisms (SNPs) as markers.
To determine whether 8q24 acts as a single region associated with all of these cancers or if it could be sub-divided into smaller regions, Maya Ghoussaini, Ph.D., of the University of Cambridge and colleagues tested the associations of nine SNPs spaced along the region in four different sets of DNA, each comprising patients with one of the four cancers and healthy controls.
The authors' analysis suggests that there may be five distinct subregions within 8q24, separated by sites of frequent recombination, and each associated with different types of cancer. The first subregion is associated with an increased risk of prostate cancer but not with risk of breast, colorectal, or ovarian cancer. The second is associated only with an increased risk of breast cancer. The third subregion is associated with the risk of prostate, colorectal and ovarian cancers, but not breast, and subregions four and five were associated with prostate cancer, but not with the other three malignancies.
"We have shown there are at least five independent loci within this gene desert with different associations with particular cancers," the authors write. "Further studies of the region may identify additional loci associated with specific cancers and possibly refine our understanding of the mechanisms underlying the associations reported here."
- Ghoussaini et al. Multiple Loci With Different Cancer Specificities Within the 8q24 Gene Desert. JNCI Journal of the National Cancer Institute, 2008; DOI: 10.1093/jnci/djn190
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