Monday, October 1, 2007

What the F*&^

After reading Hsien's recent post, I am convinced how very much the UK needs a Sherpa. Listen to what is going on in Great Britain from Eye On DNA.

"The UK Human Fertilisation and Embryology Authority has approved the use of preimplantation genetic diagnosis (PGD) to select embryos free of the gene for early-onset Alzheimer’s disease (AD). The couple who applied has a family history of the disease on the man’s side. His mother, grandmother, and two uncles all died from early-onset Alzheimer’s."

Human Genetics Alert has been fighting the good Sherpa fight for years. The problem....the UK is still approving these techniques. I hate to tell all of you, but this is what is coming. Why scan a genome? Why do lightspeed sequencing when you have time to wait? Why? The answer is simple. To rapidly screen blastocysts to rule in or rule out suitability for implantation. I have spoken about Reproductive, Endocrine and Infertility Specialists penchant for not caring about epigenetic implications

Future Pundit talks about the role of Preimplantation Genetic Diagnosis and its ever expanding uses. The specter of looks and intelligence for PGD rears its ugly head. Do I think this is a slippery slope, you bet. Especially when at the REI conference this April there were comments such as "We are the new geneticists" and "We determine mankind's fate" were heard by my Specialist friend. Yikes here comes Aldous........

Let's face it they have yet to standardize the medium in which embryos grow. Has anyone done a solid analysis of the alteration methylation patterns that emerge while growing embryos in different media? Wouldn't it be crazy if these PGD children had some increased risk for cancer? It could happen. This is why you can't perform PGD for mildly increased risk. Why do we call a woman greater than 35 Advanced Maternal Age(AMA)? Simple, because that was the age at which the risk of miscarriage from Amnio equalled the risk of having a child with chromosomal anomaly. Now that the risk is decreased to 1 in 400 will this change AMA? So here's the question now.

Is the risk of having an epigenetic change in your genome predisposing you for cancer etc EQUAL to the risk of disease from polymoprhism in the embryo?

The Sherpa Says: Risk = Benefit is what physicians should always think about. Just because we don't know the risk DOES NOT MEAN THERE IS NO RISK!


Berci Meskó said...

Your last sentence is so true! I'm still stoned by the story of Tangier disease (in one of your recent posts). And you know nothing about Hungarian physicians' knowledge of genetics. :)

cariaso said...

"Is the risk of having an epigenetic change in your genome predisposing you for cancer etc EQUAL to the risk of disease from polymorphism in the embryo?"

We don't know the risk of epigenetic change.

But published studies have measured the risk of rs4420638(G;G) as 25x with a p value of 5.3 x 10 e-34.

This may not be quite as crazy as you make it sound.

My one sentence summary above is a gross simplification, but the link above will provide primary sources for anyone curious to dig a little deeper.

Steve Murphy MD said...

I would love you to qualify what you mean by measured risk. Are you talking about OR in the AlzGene Meta-analysis? I dug deeper. I am not impressed by the meta-analysis of this. Most importantly we need to quantify htz vs. hmz. I think you can confuse readers by posting a risk without saying what is required to achieve that risk.
it appears SNPedia needs some editing....