Navigenics #4 - “Low penetrance genes v high penetrance genes”
April 9, 2008 by Elaine
Filed under Cancers, Genetic Testing, Personalized Medicine
In this fourth in the series of articles originating from G&H’s exlusive interview with Navigenics’ Medical Director Dr Michael Nierenberg, we look at the whole issue of low penetrance versus high penetrance gene testing.
SNPs are known as ‘low penetrance genes’ where it will only sometimes produce the symptom or trait with which it has been associated at a detectable level. In this case of low penetrance it is difficult to distinguish environmental from genetic factors.
Whereas ‘high penetrance genes’ such as the breast cancer genes BRCA 1 and 2 are those where the trait will almost always be shown by the individual carrying the faulty gene. In this case a BRCA 1 and 2 carrier will have over an 80% chance of developing breast and/or ovarian cancer in their lifetime.
Most high penetrance genes have been patented, in the case of BRCA 1 and 2 by Myriad Inc. It is a costly process to obtain a license from the patent owner and in the case of BRCA 1 and 2 the cost of a Myriad test is around the US $5,000 mark, two to five times more expensive than genomic screens and therefore probably prohibitive to genomic screening companies, in cost terms.
Dr Nierenberg advises that Navigenics have made a conscious decision not to include high penetrance genes in their core panel, preferring to focus on those low penetrance genes that are affected by environmental factors.
“In the case of the BRCA genes, only a relatively small proportion of the population – as low as 5% - carry one or more of these genes. We are focused on SNPs that are apparent within whole populations. We make it clear in our literature that we do not test for this type of gene.”
To learn more about the company and its thoughts on key issues surrounding the genomics industry, look out for the following articles which will be posted throughout this week.
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Check out what others are saying about this post...[...] [2] The industry line is that users shouldn’t know about some high-penetrance genes for reasons including “it’s for your own good” and “high penetrance genes are not common enough,” but the real reason is that these genes are defended by walls of patents, expensive licenses, and litigious companies. “Low penetrance genes v high penetrance genes” [...]