Sunday, September 28, 2008

Genetic Screening: Promise and Pitfalls

Leroy Hood wants to revolutionize medicine though genetic screening. I have three problems with this.

1. Leory Hood is the cocreator of automated DNA sequencing. I'm not sure if Caltech pays him part of the royalties or not, but I'm guessing the answer is yes. So there's a conflict of interest.

2. There is a phenomenon called genetic buffering whereby one gene's product masks genetic variations from other mutant genes. An example of this is HSP90, a heat shock protein, that helps other proteins fold properly.

"Rutherford and Lindquist conclude that under normal conditions, HSP90 compensates for the small genetic glitches that would otherwise alter the stability and function of the fly's proteins."

Science 4 December 1998:
Vol. 282. no. 5395, p. 1796
DOI: 10.1126/science.282.5395.1796a

Genetic buffering has been seen in plants as well.

Science 28 June 2002:
Vol. 296. no. 5577, pp. 2348 - 2349
DOI: 10.1126/science.1073846

3. Environmental buffering affects phenotype as well. It has been shown that vitamins can promote correct protein folding in mutant proteins. The vitamin acts as a scaffold to help the protein fold properly. I wrote about this earlier. It turns out that drinking alcohol increases the amount of aldehyde dehydrogenase 2 in heart tissue and this enzyme prevents cellular damage and death during a heart attack. The researchers already have found a drug to produce the same protective effect as alcohol. So, it's not just the polyphenols in wine and beer that protect drinkers from heart attacks, but the production of aldehye dehydrogenase 2 as the cells metabolize the ethanol.

Science 12 September 2008:
Vol. 321. no. 5895, pp. 1493 - 1495
DOI: 10.1126/science.1158554

Genetic screening is a tool. It is also in its infancy and requires context. If done properly it will save lives and resources. If done poorly, it will waste resources and lead doctors down the wrong path resulting in lost time and effort. There is also the issue of genetic discrimination. If you have a mutant allele known to increase the risk of having a particular cancer, an insurance company might label that as a pre-existing condition. I'm not up on the law. Congress might have addressed that issue by now, but it is still a concern.


Yeah the risk is there that medical companies could earn billions on employee or prespective mother/father screenings. This could sharply raise health insurance costs.

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