April Hot Topic: Why our kids' genes matter
The recent donor reform industry conversation in Chicago featured some excellent speakers about genetics, among other things. Every day that we learn more from geneticists about what our DNA says about us is another day that reiterates how important it is that our children have access to their full medical backgrounds from a genetic standpoint. Having anonymous donors and limited information about birth parents puts anyone at a disadvantage.
Since this is a personal interest, I collect tidbits about what genome researchers are learning, and will add some of it here. Many of these issues are not things anyone would screen for in a donor (or in a mate), but it's compelling to realize how much our kids will someday be able to learn about themselves with a DNA map.
-- Mikki
EVIDENCE FOR A GENETIC LINK TO LUNG CANCER
By Charlotte Maden, bionews.org
Scientists have found evidence that there is a strong genetic link to lung cancer. The findings, from three teams in Iceland, France and the US, will help understanding of the genetic basis of the disease and the role tobacco plays in its development.
Lung cancer is the most common killer of all cancers, with more than one million cases worldwide diagnosed annually. Until now, the cause was thought to be largely environmental - tobacco smoking. These results however, reported online in the journal Nature Genetics, show for the first time that a genetic variation could predispose a person to the disease.
The researchers carried out a two-stage genome-wide association study on 11,000 smokers in Iceland and 32,000 lung cancer patients from around the world. They looked at frequencies of 'single nucleotide polymorphisms' (SNPs), which are single-letter variants in the DNA. A region on chromosome 15 was pinpointed where SNPs were found to be associated with the disease. The region contains genes for nicotinic acetylcholine receptors, which
interact with nicotine and other tobacco toxins. About 50 per cent of the population have one allele with the variant, which raises the risk of lung cancer by about 30 per cent. If a person has two copies of the variant, however, the risk of developing the disease can increase to 80 per cent.
Despite the unequivocal evidence of the genetic link, the groups disagree over whether having the DNA variants predisposes people to lung cancer directly, or indirectly, by increasing addiction to cigarettes. Paul Brennan, of the International Agency for the Research on Cancer in Lyon,
France, and Dr Christopher Amos who led the US study at the University of Texas M.D. Cancer Center, believe that there is no evidence that the genetic effect depends on nicotine intake, so the risk of the disease is independent of smoking. 'Any association with nicotine must be modest' says Brennan, and he adds that 'a lot more work is required in this area'.
Kari Stefansson of deCODE Genetics in Reykjavik, Iceland, who led the third study, believes that the genes make people more vulnerable to nicotine addiction, thereby promoting cancer.
Another example of how our DNA reveals our health issues
GENE CLUE TO ASTHMA UNCOVERED
By Stuart Scott, bionews.org
U.S. researchers have identified a gene that seems to play a significant role in the development of asthma. Reporting in the New England Journal of Medicine, Carole Ober and her colleagues at the University of Chicago found that people can either be protected from asthma or find their risk of developing it increased, depending on which version of the CHI3L1 gene they inherit.
'This is exciting because it connects asthma susceptibility to a whole new pathway at the protein and the genetic levels. There is a good deal more we need to find out about this connection, but now we know where to look', said Ober.
