PGD, BRCA, and the difference between Diseases and Risk Factors: “The lamps are going out . . .”

It is currently estimated that up to 65% of women with the BRCA gene mutation will develop breast cancer. Monday’s Wall Street Journal (WSJ) reported on the growing number of women with the BRCA gene mutation who are undergoing in-vitro fertilization, having the resultant embryos tested for the presence of the mutation via preimplantation genetic diagnosis (PGD), and choosing to implant only those free of the mutation.

PGD has been used for years, typically for parents to selectively implant embryos free of certain genetic diseases — the kind where if you have the gene, you have the disease. It has been occasionally used to select embryos of a certain sex, or embryos with a characteristic such as deafness to match parental characteristics. In other words, it has been used to select out embryos who actually have a disease or characteristic.

The use of PGD mentioned in the WSJ article is something subtly but altogether different. Whereas other uses of PGD select out embryos with a certain disease, screening based on the BRCA gene is used to select out healthy embryos. These are embryos who do not have a particular disease, but who have risk factors for a particular disease.

This is a fundamental distinction. People who have the BRCA mutation are not sick! They don’t have any disease! If they develop cancer, then they will have a disease. But “Having the BRCA mutation” is not a disease! Approximately 35% of people with the mutation will never have the disease associated with the mutation. For the others, preventive measures and treatments are available. (I am not here pretending that the preventive measures and treatments are fun and easy. But they available and mainstream, not experimental.)

The rationale of one person in the article is, “I thought, if I could have a healthy baby who doesn’t have to worry about the same thing I did, why wouldn’t I?” And, “. . . doing PGD to avoid passing on the BRCA mutation seemed like an obvious precaution.” In other words, the decision was a no-brainer.

But if it’s a no-brainer to select out embryos with the BRCA mutation, then it’s equally a no-brainer to select out embryos with genetic predispositions to all kinds of things: heart disease, diabetes, social anxiety disorder, baldness, ingrown toenails, erectile dysfunction . . .

It was at the moment that it became acceptable to profile embryos and weed out those who didn’t meet our arbitrary criteria that we started down this road. I am afraid we will not be able to stop before it reaches its inevitable, logical conclusion. (Seen Gattaca lately?)

 

 

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Steve Phillips
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To follow up what I have been writing about related to this recently, we need to help people understand that when they do PGD they are saying that the lives that would be lived by the embryos that are discarded are lives that would not be worth living. When in such a situation a person needs to think “if it had been known when I was an embryo that I had the BRCA gene should I have been discarded so that I would never have lived?”