Genetics and Health

Twins Born After Preimplantation Genetic Haplotyping

by Hsien Hsien Lei, PhD on November 14th, 2006

A pair of twin boys have been born free of the genes for cystic fibrosis after they were selected as embryos using preimplantation genetic haplotyping (PGH). Interestingly, their parents opted to undergo PGH even though they already have a previous set of twins, one of whom has cystic fibrosis.

Unlike the more common method of preimplantation genetic diagnosis (PGD), PGH does not test for specific mutations, but instead identifies a more general DNA pattern that is associated with the disease and is unique to each family. This technique is particularly helpful for families in which the exact gene mutation is not known or is very uncommon.

And here’s a thought that hadn’t really crossed my mind before: The Times Online article discusses X-linked disorders and how only girl embryos were implanted in the past because they have a lower probability of developing the disease given their double dose of the X chromosome. With PGD/H, this would no longer be the case and “healthy” male embryos could be implanted for couples who carry an X-linked disease gene. (I put healthy in quotes because nobody is truly 100% healthy.)

Mother Catherine Greenstreet in The Daily Mail:

Today, Mrs Greenstreet, 38, defended her decision to reject the imperfect embryos, saying she and husband Jim, 41, did not want to repeat the experience of caring for a seriously ill child.

“Unless you have lived with a child that has a terrible disability or disease then you can’t speak about it,” she said.

“Who can criticise you for trying to get rid of horrible diseases? Why would you want to see people suffer? When you have got these lovely healthy babies in your arms it dampens all the pain we went through. They are designer babies but they are designed for the good of mankind.”

I wish the Greenstreets all the best but know that life and health are not so clear cut.

Technorati Tags: cystic fibrosis, preimplantation genetic diagnosis, PGD, preimplantation genetic haplotyping, PGH, IVF, genetics, genes, dna, diseases, embryos, health

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