According to an article from Stat News, patients, doctors, and advocates around the country are starting to push more energetically for a repeal of a U.S. law that effectively bans mitochondrial replacement therapy – a controversial form of fertility treatment and preventative medicine that combines genetic material from three people to create one offspring.
Yes – it’s a treatment that, genetically, gives one kid three parents.
And yes, I do realize that this flies in the face of everything you read in your middle school sex ed class. How does it really work though? What does it mean to have “three parents”?
All About Mitochondrial DNA
Before you can understand that, it’s important to understand that you have two kinds of DNA in your body. There’s the typical DNA you’re thinking of right now, present in every cell nucleus throughout the body, providing the coded instructions for every developmental change you’ll ever undergo. Then you have mitochondrial DNA.
Mitochondrial DNA is just that. It’s a much smaller sequence of DNA – just one small chromosome of 37 genes – that is unique to your mitochondria. Unlike “generic” DNA that is a mishmash of your parents’, mitochondrial DNA is inherited directly from your mother. That means your mitochondrial DNA and your mother’s are the same – and so is your mother’s mother’s, and so on!
That is, unless you experience a mutation.
Like nuclear DNA, mitochondrial DNA is susceptible to unpredictable changes to its proper sequence. If a woman further up your family tree has a mitochondrial DNA mutation, she will pass it said mutation to all of her offspring. This is how many conditions linked to mitochondrial DNA persist.
My Dad, my Mom, my Other Mom, and Me
Mitochondrial replacement therapy begins with an egg that has malfunctioning mitochondria. The nucleus of this egg, containing the mother’s half of the genetic material that will be passed to the offspring, is then transplanted into a donor egg with healthy mitochondria. The donor egg (which previously had its own nucleus removed) is then fertilized by a spermatozoa, and a healthy embryo is formed with DNA from three individuals.
This is how one person can, technically, have three parents.
The technique has been in use in Europe as a fertility treatment, but advocates in the United States are more interested in the procedure’s applications for preventing the transmission of mitochondrial disease. However, a 2015 congressional amendment effectively banned the treatment. Fears of “genetic engineering,” or genetically modifying a person’s genetic code for their advantage, were magnified by last year’s CRISPR incident – when a Chinese scientist became the first to genetically modify a pair of twin girls as embryos.
It’s through this umbrella fear of genetic engineering that mitochondrial replacement therapy was banned in the United States. I. Glenn Cohen, a professor at Harvard Law, believes the ban could be challenged through a number of avenues:
- A change in the language of the amendment, which must be renewed annually
- A change in FDA interpretation of said amendment, or
Cohen admits that while a lawsuit could be effective, it could take years to reach a resolution. A change in FDA policy or the language of the law itself could come about much easier and faster.
About one in every 1,000 to 4,000 births in the United States produce offspring with mitochondrial disease – meaning that in one way or another, we need a way to treat these people. So-called “three-parent IVF,” though still controversial (for some reason) in parts, represents an obvious chance to limit the number affected.
Why do you think a therapy, that is so clearly effective, is also so controversial in the United States? Do you think moral debate has a place in medicine? Share your thoughts with Patient Worthy!