I've come across this article from BBC News : Warning of three-person IVF 'risks'
The debate was launched by scientists from the University of Sheffield and the University of Sussex in England, and Monash University in Australia. Here is what it is about.
I completely agree with the Human Fertilisation and Embryology Authority on this. There shouldn't be any risk for a child having a different mtDNA from one's mother. This is ludicrous.
Previously other people had voice ethical concerns about babies born from a three-person IVF because they would be having two biological mothers instead of one. This is also nonsensical for two reasons:
1) Mitochondrial DNA only represents a tiny fraction of one's genome. It is made of 16,569 base pairs, as opposed to over 3 billion base pairs for the chromosomal DNA. In other words mtDNA is only 0.0005% of our DNA. That could be less than the number of copying errors happening from one generation to the next. A lot of people are born with DNA deletions or extra copies of some genes longer than that, which their parents didn't have. What's more, getting a third person's mtDNA does not mean having 16,569 characters in one's DNA that differ from the true biological mother. It could be just a handful of mutations, or at most something like a hundred, since the variations found within human mitochondrial genomes are very minor. For example there are only 8 mutations differentiating an individual belonging to mtDNA haplogroup H2a2 from someone who is H3a1a, to cite to common Western European maternal lineages. What is a difference of 8 characters out of 3 billion ? Actually there is sometimes more difference between the DNA contained in two different cells in our body, due to copy mistakes that are inevitable during cell division. So mtDNA in itself is too tiny to have any claim at all on parenthood.
2) It sometimes happen that the two parents of a child share the exact same mtDNA. For example if they are (first, second, third, fourth, etc.) cousins on their maternal side. This is because mtDNA can be passed unaltered for dozens of generations. For this reason it is not impossible to find an egg donor who shares the same mtDNA as the father to replace the mother's defective mtDNA. In that case the father and the egg donor would have exactly the same claim on the mtDNA. Or for that matter any individual who possess an identical mtDNA haplogroup, and there could be tens of thousands of them. This would again completely disqualify the egg's donor claim to motherhood regarding the child born in a three-person IVF. If there is absolutely no difference in genetic sequence between the donor's mtDNA and, say, her sister, her maternal cousin, or a perfect stranger who inherited the same mtDNA from an ancestor many centuries ago, then it is impossible to prove whose mtDNA it is. Mitochondrial DNA is actually quite impersonal justly because it is shared identically between so many individuals in society.
The debate was launched by scientists from the University of Sheffield and the University of Sussex in England, and Monash University in Australia. Here is what it is about.
BBC News said:Mitochondria are the tiny, biological "power stations" that provide nearly every cell, which make up the body, with energy. They are passed from a mother, through the egg, to her child.
But if the mother has defective mitochondria then it leaves the child starved of energy, resulting in muscle weakness, blindness and heart failure. In the most severe cases it is fatal and some families have lost multiple children to the condition.
The proposed therapy aims to replace the defective mitochondria with those from a donor egg.
But mitochondria have their own DNA, albeit a tiny fraction of the total. It means a baby would have genetic information from mum, dad and a second woman's mitochondria.
The concerns raised - by scientists at the University of Sheffield, the University of Sussex and Monash University in Australia - are about a poor match between the mitochondrial DNA and that from the parents.
They said there was an interaction between the DNA in the mitochondria and the rest which is packaged in a cell's nucleus.
Their studies on fruit flies suggested that a poor match of genetic information between the nucleus and mitochondria could affect fertility, learning and behaviour.
...
The Human Fertilisation and Embryology Authority, which regulates fertility treatment in the UK, commissioned a review into the safety of the technique.
Prof Robin Lovell-Badge, who was on the review panel, disagreed. He said humans had diverse mitochondrial and nuclear DNA, so any consequences of poor matches would have already become apparent.
He told the BBC news website: "Humans are breeding between races and producing healthy children all the time. If there is an effect then it must be very trivial as it's not been noticed."
I completely agree with the Human Fertilisation and Embryology Authority on this. There shouldn't be any risk for a child having a different mtDNA from one's mother. This is ludicrous.
Previously other people had voice ethical concerns about babies born from a three-person IVF because they would be having two biological mothers instead of one. This is also nonsensical for two reasons:
1) Mitochondrial DNA only represents a tiny fraction of one's genome. It is made of 16,569 base pairs, as opposed to over 3 billion base pairs for the chromosomal DNA. In other words mtDNA is only 0.0005% of our DNA. That could be less than the number of copying errors happening from one generation to the next. A lot of people are born with DNA deletions or extra copies of some genes longer than that, which their parents didn't have. What's more, getting a third person's mtDNA does not mean having 16,569 characters in one's DNA that differ from the true biological mother. It could be just a handful of mutations, or at most something like a hundred, since the variations found within human mitochondrial genomes are very minor. For example there are only 8 mutations differentiating an individual belonging to mtDNA haplogroup H2a2 from someone who is H3a1a, to cite to common Western European maternal lineages. What is a difference of 8 characters out of 3 billion ? Actually there is sometimes more difference between the DNA contained in two different cells in our body, due to copy mistakes that are inevitable during cell division. So mtDNA in itself is too tiny to have any claim at all on parenthood.
2) It sometimes happen that the two parents of a child share the exact same mtDNA. For example if they are (first, second, third, fourth, etc.) cousins on their maternal side. This is because mtDNA can be passed unaltered for dozens of generations. For this reason it is not impossible to find an egg donor who shares the same mtDNA as the father to replace the mother's defective mtDNA. In that case the father and the egg donor would have exactly the same claim on the mtDNA. Or for that matter any individual who possess an identical mtDNA haplogroup, and there could be tens of thousands of them. This would again completely disqualify the egg's donor claim to motherhood regarding the child born in a three-person IVF. If there is absolutely no difference in genetic sequence between the donor's mtDNA and, say, her sister, her maternal cousin, or a perfect stranger who inherited the same mtDNA from an ancestor many centuries ago, then it is impossible to prove whose mtDNA it is. Mitochondrial DNA is actually quite impersonal justly because it is shared identically between so many individuals in society.