Genetics and Health

Don’t Rain On My Gene Parade

by Hsien Hsien Lei, PhD on May 12th, 2006

The dream: To find genes that confer a high risk for common diseases like cancer and heart disease.

It’s been done before - BRCA1, BRCA2, HNPCC are all genes which significantly increase the risk of breast, ovarian, and colon cancers. But Stuart Baker, of the US National Cancer Institute in Bethesda, Maryland, and Jaakko Kaprio, a genetic epidemiologist from the University of Helsinki, aren’t so sure there are too many more of these genes to be found. They have three reasons for why they think projects like the Cancer Genome Atlas won’t succeed:

1. Many genes are involved in the development of tumors. Perhaps too many to be enumerated.
2. Studies of immigrants show that cancer rates become similar to the adopted country’s within one or two generations. Too soon to attribute to changes in genetic make-up.
3. Twin studies have not shown that identical twins have a greater chance of developing the same types of cancer. This implies that genetic influences are not that strong.

The authors calculated on the basis of these results that only 9 to 22 per cent of prostate cancers would be found in people with susceptible genes, 8 to 14 per cent of breast cancers, and 5 to 13 per cent of bowel cancers.

Translating those percentages into actual numbers using only UK stats:

• In 2002 there were 31,923 new cases of prostate cancer diagnosed in the UK. If 9 per cent of them were caused by genes, that would equal 2,873 people. At 22 per cent, it would be 7,023 people.
• For breast cancer, 41,700 women in the UK are diagnosed each year along with 300 men. This translates to between 3,360 to 5,880 breast cancer cases attributable to susceptibility genes.
• In the case of bowel cancer, almost 34, 900 people are diagnosed every year in the UK. So between 1,745 and 4,537 cases could be caused by genes.

While the numbers aren’t overwhelming, I still think they’re significant. Also, the discovery of genes contributes to the general understanding of how our bodies work. It isn’t simply a means to an end.

The Times Online, May 12, 2006

Technorati Tags: genes, genetics, cancer, disease, health, dna, stuart baker,

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POSTED IN: Genetics of Disease