Dr. Robert Marion on Preimplantation Genetic Diagnosis

Dr. Robert Marion on Preimplantation Genetic Diagnosis

by Dr. Hsien-Hsien Lei
Posted August 20, 2009 in DNA Testing, Personalities with DNA

genetic rounds robert marionHere’s part 2 of my interview with Dr. Robert Marion, whose new book, Genetic Rounds, will be published in October. (See Part 1 for Dr. Marion’s thought on medical writing.)

One of the most touching aspects of Genetic Rounds was your concern for the families of patients affected by genetic disorders. Some would-be parents turn to preimplantation genetic diagnosis (PGD) so as to avoid passing down certain genetic mutations to their offspring. What are your feelings about PGD?

Dr. Marion: My feelings are mixed.  PGD is an amazing tool, an opportunity that allows families like the Kennedys in "Genetic Rounds" who, because of the birth of a previous child with a devastating genetic disorder (in their case, Spinal Muscular Atrophy) have decided not to have more children, to safely reproduce and raise a family.  As such, it’s a technique that allows babies who would not have been conceived to be born.  So, from that perspective, it is an incredible breakthrough.

The problem I see, however, is that I don’t think we’re certain of what effects PGD and in vitro fertilization in general  might be having on the pre-embryo and embryo.  Recent work showing an increase in conditions in which epigenetic disturbances may play a role, such as Beckwith Wiedemann syndrome, points to our need for additional information about how extra-corporal fertilization (a technique that’s necessary for PGD) affects gene silencing and gene expression.  Until these studies have been completed, we have to continue to be cautious.

However, I think the benefits of PGD clearly outweighs the risks. 


I recently received an email from a reader who’d undergone preimplantation genetic diagnosis prior to conceiving their children by IVF. Unfortunately, the genetic mutation they were concerned with was not picked up during the screening. With permission, here’s the email I received:

My wife and I underwent IVF and PGD testing to try and avoid passing on a genetic condition which she carries.  Her mutation had been previously identified by a certified and highly respected laboratory.  Three embryos were implanted and we were elated at the birth of our fraternal twin sons.  Almost immediately, my wife recognized the signs of her condition in one of our sons.  A blood sample was drawn from him and from my wife.  These were sent to another highly respected lab that confirmed 1) the initial laboratory successfully and properly identified my wife’s mutation and 2) our son has the condition.

The laboratory that performed our PGD refuses to respond to our inquires.  We just want to know and understand what happened — and that someone gives a damn.

Prior to undergoing the procedure, we thoroughly weighed and examined the moral and practical issues surrounding IVF & PGD.  I researched the topic as much as I possibly could and kept running across assurances such as "error rates approaching zero."  Heck, that’s better than what you get for any medical procedure! 

I can’t begin to explain to you how alone we felt.  It would be helpful to know that someone else has gone through this before… (emphasis added)

What are your thoughts on preimplantation genetic diagnosis? Do you have some kind words to share with this reader? For more information, see my previous post – Genetic Testing to Prevent Wrongful Life.



Related Posts:
Dr. Robert Marion on Physician Knowledge of Genetics...
Dr. Robert Marion on Direct-to-Consumer Genetic Testing...
Dr. Robert Marion on Complex Genetic Diseases...
Preimplantation Genetic Diagnosis (PGD): A Discussion...
Medical Geneticist Dr. Robert Marion on Writing...
Genetic Rounds by Dr. Robert Marion...
Eye on DNA Links – June 19, 2007...

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Comment by Steven Murphy MD Subscribed to comments via email

Bob and Judy Willner and I and a whole host of others agree with the untoward results. We just don’t know what the risks are……

PGD for deadly disease probably a good thing. But for BRCA genes??????

Not so much.


Thanks for the comment, Steve!

What would you tell patients who want PGD because their family has been devastated by a history of breast and ovarian cancer? Not having been in that situation, I don’t know if I’d be comfortable denying people the choice.


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