Researchers at the Wellcome Trust Centre at Newcastle University in England are trying to win government approval for a new in-vitro fertilization (IVF) technique to supposedly eliminate some mitochondrial diseases from being passed from mother to child. Sensational headlines are calling this “three-parent IVF” or “designer babies.” You might wonder why I am tackling this topic on a Bible blog. This is actually is a perfect opportunity for some theology practice. Biblical knowledge has to be applied to the problems of today, or it is just trivia.
We receive two kinds of DNA at conception. Nuclear DNA (over 3.3 billion base pairs) comes equally from mom and dad. Each cell has one copy of this genetic blueprint. We also receive mitochondrial DNA (16,569 base pairs), but this comes only from mom. Since we have lots of mitochondria in each cell, there are lots of copies of the mtDNA in each cell. According to the best theories of researchers, mtDNA is only involved in the process of turning sugars (or fats) into energy. They do not think it has any impact on identifiable characteristics (height, eye color, etc.).
The IVF procedure under consideration fertilizes an egg from the mom with a known mtDNA defect with sperm from dad. The nucleus of the fertilized egg is then transplanted into the “hollowed out” egg from a woman who has no known mtDNA defect. The resulting child, then, has nuclear DNA from mom and dad and the mtDNA from a second woman. It is true that the mtDNA is just 0.1% of the total nuclear material. It is stretching the facts to declare the second woman a second mother. (However, the legal and ethical issues surrounding the recipient’s notification and donor’s rights would have to be addressed.)
Despite the small percentage of total genetic material being replaced, I think this is a very risky medical option that may not even be needed. Most mitochondrial diseases (75%) are linked to something other than mtDNA defects (nuclear DNA, environmental factors, etc.). This procedure would not avoid any of these causes. Even a known mtDNA defect does not guarantee that a mom’s children will exhibit symptoms. One defect, called LHON, causes severe vision problems. But it only occurs in 50% of boys and 10% of girls with an affected mother.
Secondly, researchers do not know every mtDNA mutation that might cause a mitochondria-related disease. A mtDNA transplant would not guarantee perfectly healthy mtDNA. An unidentified defect might be passed along from the donor. Researchers also do not understand all the complex interactions of nuclear DNA with mtDNA. It is clear that in most cases of mitochondrial disease (not maternally inherited), some nuclear genes are involved. Replacing the mom’s mtDNA with another woman’s mtDNA brings the risk of actually causing new problems because of the unknown interactions between nuclear DNA and mtDNA. (UPDATE: This recent research demonstrates how a single gene defect in the nucleus or mitochondria may not cause a problem, but the combination does.)
I admit, I am not a doctor or genetic specialist. However, as an educated layman, there are so many unknowns and uncertainties that the risk seems unjustified. Hurting families should not be test cases, especially when there are clearly superior options, such as adoption or even trusting God.
Why am I singling out this procedure for examination? Our daughter Gwendolyn has a mitochondrial disease. We have had to learn about mitochondrial diseases and genetics. We have had to make decisions weighing medical science against faith. Gwendolyn’s exact genetic diagnosis is still unknown, but it suspected to be autosomal recessive (coming as a combination of nuclear genes from mom and dad). They have not found a specific defect in her mtDNA (which came from Melanie). This type of inheritance implies a 25% risk for us having another child with all of Gwendolyn’s severe symptoms.
In part two, I look at the theological problems with this procedure…
“mtDNA and Mitochondrial Diseases”
“Mitochondrial Disease Inheritance and Genetics ”
“And three make the perfect baby”
“Three-Parent IVF Could Reduce Disease, But Stirs Debate ”
“Ethics debate opens into ‘three-parent’ IVF technique”
“Mitochondria vs Nucleus“