Genetics plays a key role in determining risk for colorectal cancer, the second leading cause of cancer-related deaths in the United States.
Several common genetic markers have been found to be associated with the disease, but finding the biological events that lead to cancer can be much more difficult. In a study published online in Genome Research (www.genome.org), scientists have identified a common genetic variation associated with the risk of colorectal cancer and its functional implications, shedding new light on the basis of this deadly disease.
Hunting down the genes that underlie diseases such as colorectal cancer is extremely difficult, owing to the genetic heterogeneity of cancer cells. Numerous mutations can be found in a cancer cell, but the key to developing new treatments and therapies is to identify the variants that cause the disease hidden amongst many mutations that are simply bystanders. Recently, researchers have been aided in this search by the genome-wide association study (GWAS), a technique that scans the genome for known common genetic variants, also known as single nucleotide polymorphisms, or "SNPs," that are more prevalent in patients with a specific disease. However, a SNP associated with a disease is not necessarily the culprit – but it raises a red flag that something important is nearby.
In this study, an international team of researchers led by Dr. Richard Houlston of The Institute of Cancer Research in the United Kingdom have delved into the biology underlying common variants on chromosome 18 that his group recently found to be associated with colorectal cancer in a GWAS. They sequenced the region of DNA surrounding these markers in a large group of colorectal cancer cases and controls, identifying all variants residing in this chromosomal region common to colorectal cancer patients.