In order to try to prevent mitochondrial DNA defects which affect 1 in 5,000 people and are usually mild, researchers in Britain hope to create human embryos that have the nuclear DNA from their parents but healthy mitochondrial DNA from an egg donor.
Times Online describes the technique: "First, an egg from a woman carrying mitochondrial defects will be fertilised in vitro using her partner's sperm. At the point of fertilisation, two "pronuclei" containing genetic material from the mother and father will be removed, and injected into an unfertilised egg from which the nucleus has been removed.
This donated egg will contain healthy mitochondria, but none of the nuclear DNA that makes up most of the human genetic code."
Doesn't that sound eerily familiar to somatic cell nuclear transfer, aka cloning. Instead of a somatic cell being taken from an adult patient, two pro-nuclei are taken from what sounds like a human zygote.
The Times Online article says it's not cloning because "the embryo that develops as a result will have a full complement of genes in its nucleus from a mother and a father. Clones created by nuclear transfer are genetically identical to the adult from which they are cloned, with the exception of their mitochondrial DNA."
I'm not buying this since cloning is cloning regardless of whether a human embryo is being cloned from a human adult or from a human embryo.
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ReplyDeleteHi Kevin,
ReplyDeleteThe Times explanation seems to imply that clones can only be created from adults which is wholly incorrect. Organisms of any stage of development can be cloned. My main point against the article was the seeming implications that only adults could be cloned.
The article seems to indicate that the genetic material comes from an embryo or zygote. I may be incorrect but that how the article reads to me.
If a scientist takes cells from an embryo and then inserts them into a nucleus-free egg and zaps them - isn't the resultant embryo a clone?
Just because the embryos whose cells were removed no longer exists/is dead in no way determines whether the created entity is a clone or not.
Taking a cell from one organism and placing it in a nucleus free egg is much different than a mere change in location.
Do you think the survival rate for these embryos will be high? If the success rate is low, wouldn that indicate that maybe something more than a mere change in location is taking place?
I guess its a question of whether you believe that an organism is a bodily entity or just their DNA.