Friday, May 20, 2016

Coming soon: Mass reproduction via IVF and Preimplantation Genetic Diagnosis (PGD)

It's interesting that only the World War II Axis Powers that have outlawed pre-implantation genetic diagnosis ("DPI interdit"). I suppose the Germans, given their track record, fear that they would misuse the technology if given half a chance.

The New Statesman
"It is already possible to avoid more than 250 grave genetic conditions by genetic screening of few-days-old embryos during in vitro fertilisation (IVF), so that embryos free from the genetic mutation responsible can be identified for implantation. But that usually works solely for diseases stemming from a single gene – of which there are many, though most are rare. The procedure is called pre-implantation genetic diagnosis (PGD), and it is generally used only by couples at risk of passing on a particularly nasty genetic disease. Otherwise, why go to all that discomfort, and possibly that expense, when the old-fashioned way of making babies is so simple and (on the whole) fun?
In The End of Sex, Henry Greely, a law professor and bioethicist at Stanford University, argues that this will change. Thanks to advances in reproductive and genetic technologies, he predicts that PGD will become the standard method of conception in a matter of several decades. (Recreational sex might nonetheless persist.)
If that doesn’t sound alarming enough, there will be all manner of other seemingly bizarre and alarming options on the menu for making children: using eggs and sperm both made from a single adult (the “uniparent”), or chromosomes tailor-made by chemistry, or IVF between siblings or pensioners, or IVF with the stolen biological detritus of celebrities.
Greely does a superb job in his book of explaining the science, as well as the law and politics (at least in the US context), that will make these things possible. At the root is the realisation that human tissue is far more malleable and protean than we had imagined. Every cell in your body – a flake of skin, say – could be a source not just of most or all other tissue types, but of other beings.
Central to these scenarios is the culturing and manipulation of stem cells, the ur-cells from which all others develop. The most versatile are human embryonic stem cells. Because these are “pluripotent” – able to grow into any tissue type – they might be used for regeneration of damaged tissues such as nerves, heart muscle and bone.
But it was first shown in 2014 that they can also be used to generate “gametes”: eggs and sperm. So far, such “artificial sperm” consists of immature “spermatids”, which lack tails for swimming. That is no obstacle, however. Using methods developed for IVF, the cells can be injected directly into eggs to produce apparently healthy offspring – in mice, at least. If we want to make babies this way, we’ll generally want them to have the parental genes. It is possible to create embryonic stem cells containing the genes of an adult by using methods involved in cloning Dolly the sheep, in which genetic material is transferred from an adult body (somatic) cell into an egg that has had its own chromosomes removed. The egg can then be used to grow an embryo – a clone – from which stem cells can be cultured. When will that happen? Two years ago."


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