Researchers from the University of Oxford and the Institute of Cancer Research in London sequenced the entire genomes of 20 people whose families had a strong history of bowel cancer. Eight of the participants had bowel cancer and the others had a close relative with the disease. The researchers found that the participants who had a faulty copy of either the POLD1 or POLE gene went on to develop the disease or had a precancerous growth in the bowel.
To investigate this link, the researchers then looked at the genomes of 4,000 people with bowel cancer and 6,700 people without. Neither copy of the faulty gene was seen in the group without bowel cancer but 12 participants in the cancer group showed a fault in the POLE gene and one person showed a fault in the POLD1 gene.
The POLD1 fault was also linked to seven cases of womb cancer and one brain tumour. The researchers explained that without working copies of the genes, which are involved in the repair of damaged DNA, DNA replicates incorrectly and cells can become cancerous. The findings provide one explanation for why people with a family history of bowel cancer have an increased risk of getting the disease.
Professor Tomlinson, who led the team at the Wellcome Trust Centre for Human Genetics at the University of Oxford, said: 'There are some families where large numbers of relatives develop bowel cancer but who don't have any of the known gene faults that raise the risk of developing the disease. These two faults are rare, but if you inherit them your chance of bowel cancer is high'.
He went on to explain that, in the short term, these results could be used to work out who was at a higher risk. The long-term plan is to increase screening for these mutations in high risk families.
Co-author Professor Richard Houlston of the Institute of Cancer Research underlined the importance of this research. 'Uncovering gene faults like these two is extremely important, as inherited susceptibility plays a role in the development of about a third of all cases of colorectal cancer', he said.
'This is one of the most important discoveries in bowel cancer genetics in years. It should allow us to manage families affected by inherited bowel cancer much more effectively, and it offers new clues for the prevention or treatment of all forms of the disease', he added.
The research was funded by Cancer Research UK and is published in Nature Genetics.