Last night I had the amazing privilege to attend a debate in the Houses of Parliament regarding today’s vote about whether or not to amend their 2008 Human Fertilisation and Embryology Act (HFEA). The debate was hosted by the Progress Educational Trust (PET), an independent organization that “urge(s) you to vote in favour of the Human Fertilisation and Embryology (Mitochondrial Donation) Regulations 2015.”
I’m rushing this post to press, so please forgive the lack-luster writing quality– I thought you might enjoy an update while the news is fresh. My understanding of biology is helpful, but please understand that I am no expert on this. All information provided is correct to the best of my knowledge– but if you see some errors, please let me know!
What is mitochondrial disease?
Most info in this section can be double checked on Wikipedia.
- A set of diseases caused by faulty mitochondria, the “powerhouse” organelle in the body responsible cellular metabolism– converting the food we eat into energy that is usable by our body (ATP — adenosine triphosphate)
- Symptoms: mostly effects organs that need a lot of energy such as brain (seizures, demintia); heart (cardiomyopathy “heart muscle disease”); muscles (weakness, cramping); ears / eyes / nerves (deafness, blindness, neuropathic pain)
- Although in 5th grade we learned that all our DNA is stored in chromosomes in the nucleus of our cells that we received from our parents — half from Mom (egg), half from Dad (sperm)– this is only mostly true. It’s more like 49% from Dad (stored in the sperm’s chromosomes) and 51% from Mom (49% stored in the egg’s chromosomes, 2% stored in the egg’s mitochondria). This 2% is exclusively passed through the maternal line. (eg: George’s mitochondrial DNA came from his mom, which came from her mom, which came from her mom… George’s wife will pass on mitochondrial DNA to their children.)
- While 85% of these mitochondrial diseases are caused by genetic mutations in chromosomal DNA, ~15% of mitochondrial diseases are caused by mutations in the mitochondrial DNA. This subset of mitochondrial diseases is where we focus our attention.
What is mitochondrial donation?
“A type of in vitro fertilization (IVF) that involves conceiving a child using biological material from three people — the child’s parents, plus a mitochondrial donor” (PET briefing).
You may have heard about this in the media as a “3 parent” embryo. a somewhat misleading description since parents are not just defined by genetic relations. (Think about parents of adopted children.) Even if emphasize the importance of genetic lineage, the embryo would only receive ~2% of its DNA from the “3rd parent” (the woman who donates mitochondrial DNA). Remember: 98% of the DNA is from the chromosomes of the egg & sperm.
The HFEA is proposing two specific techniques:
1. maternal spindle transfer (MST)
Mitochondria from a donor egg is transferred to the Mom’s egg. The Mom’s egg (now containing healthy mitochondrial DNA from the donor) is then fertilized with Dad’s sperm using IVF techniques.
2. pronuclear transfer (PNT)
Mom’s egg is fertilized with Dad’s sperm using IVF. A donor embryo is formed using donor egg and potentially (though not necessarily) donor sperm. The healthy mitochondrial DNA from the donor embryo is transferred to the embryo formed from the Mom’s egg and the Dad’s sperm. This technique results in the death of the donor embryo, the ethics of which are briefly outlined below.
See the HFEA’s website for more info on these two techniques.
What are the main ethical considerations?
Lots of things to consider! But for time sake (I have to run to class!) I’ll talk about two:
1. Is mitochondrial transfer safe?
Again, this is contested. Based on the debate yesterday, my understanding is that these techniques have been researched for 30+ years. The majority of this time has been spent with animal research, but the last 5 years have used human embryos. The results are promising, but we wouldn’t understand the effects until it is tested in humans.
This technique is unique in the fact that it changes the germ line. It is very difficult to predict the social and biological harms / benefits of this type of alteration. There have been a few experiments in humans that use similar techniques, (US — late 1990s, China — 2003) but the results have either been unsuccessful or indeterminate.
Note: In the US, the FDA has NOT yet approved mitochondrial donation for clinical trials. This takes for-eh-ver, so even if / when this advances to the stage of clinical trials, it will be a long time before it is available to the general public.
2. What is the moral status of an embryo?
A highly contested question. According to UK parliament (2002) the embryo has some non-negligible moral value that is less than the moral value of person after birth. This matches their policy that permits the use of IVF to select against severe genetic disease and states that embryos may be used for research purposes only when they are ≤ 14 days (“early embryos”).
One of the strongest voices on the other side of the fence is the Catholic Church, which states that “human life must be respected and protected absolutely from the moment of conception” (2270). Contrary to popular belief, the Catholic Church does encourage “research aimed at reducing human sterility” (2375). However, it opposes “techniques involving only the married couple… that dissociate the sexual act from the procreative act” (2377 — eg: artificial insemination / fertilization) and strongly opposes “techniques that entail the dissociation of husband and wife, by the intrusion of a person other than the couple” (2376). This understanding matches the Catholic teaching that sympathizes with infertile couples but maintains that a child is gift– there is no “right to a child” (2379). As such, the Catholic Church does not support the proposed changes– especially PNT which creates and destroys the donor embryo, a means to the end of creating a healthy embryo.
The vote will take place this afternoon (London time) so stay tuned to the news! Based on the views exchanged at the debate yesterday and the fact that IVF is permitted in the UK with costs covered under the National Health Service, I’m betting that this proposal will pass at least in part– definitely for MST, but perhaps not for PNT because of the ethical reasons explained above.
And if you made it through that whole post, here are some photos for your enjoyment.