On February 3, 2015, the United Kingdom’s lower house of parliament passed legislation making it the first country in the world to allow “three-parent offspring.” The “mitochondrial replacement” procedure enables a mother whose eggs contain faulty mitochondrial DNA to be replaced with the healthy mitochondrial DNA of a second woman’s egg. The resulting baby has nuclear DNA from its mother and father, but mitochondrial DNA from a second woman. This method can prevent parents from passing on rare diseases to their offspring as a result of the defective mitochondria of the mother’s egg, and results in the offspring sharing less than 0.2% of its DNA with the second woman. This achievement begs the question of whether the United States will “proceed with this complex reproductive method.”
Last year, an advisory board to the United States Federal Drug Administration (“FDA”) concluded that further research was needed concerning the long-term effects of mitochondrial replacement before the procedure could be approved in the United States. Marcy Darnovskhy, Director of the Center for Genetics and Society, opposes the procedure.  In summarizing the committee’s findings, Darnovskhy stated that the committee “concluded that the known risks and areas of disturbing uncertainty were too large to permit clinical trials to begin.” Despite the medical concerns, hesitation over approval of mitochondrial replacement is primarily due to ethical concerns of designer babies and eugenics.
Critics contend that allowing a procedure such as mitochondrial replacement would bring reproductive technologies one step closer towards designer babies. Many claim that “[i]f clinicians can alter embryos in this way, who is to say it would not eventually lead to selection of other genetic material to make smarter, stronger, more attractive kids?” Criticisms against designer babies are premised upon the worry that parents will be able to manipulate genes within the embryo in order to design future offspring. “This will be the first time that we would intentionally manipulate the human genome… and once you cross that line, then it is very hard to stop going down the slippery slope to designer babies,” said David King, Director of Human Genetic Alert.
Although mitochondrial replacement does involve changing the human genome, the genes that mitochondria relate to do not affect personal characteristics such as hair color, eye color, and other “defining traits.” Devin Oglesbee, Co-Director of Mayo Clinic’s Biochemical Genetics Laboratory, explains that mitochondria “absorb oxygen and food and turn it into energy so your heart can beat and your brain can think”. Alternatively, the genetic information that determines our physical traits are contained in the nucleus, and are inherited from the mother and father. During mitochondrial replacement, the nucleus of the second woman’s embryo is extracted and replaced with the nucleus of the mother and father. As a result, the parents are left with a baby that has the parents’ “genetics instructions” and less than 0.2% of its DNA (the healthy mitochondria) from a second woman.
Proponents of mitochondrial replacement have pointed to this information to show that the fear of designer babies is unwarranted. “We’re not talking about manipulating genes. We’re talking about a fertility technique that replaces bad mitochondria with good mitochondria,” said Dr. Bruce Cohen, Director of Neurology at Akron Children’s Hospital and a mitochondrial disease specialist. Because the nucleus from the mother and father’s DNA is passed on, all of the physical traits stay the same, and the baby’s mitochondria being is only thing that is changed.
Supporters praise mitochondrial replacement as a breakthrough opportunity to improve the health of babies. In the United States, over 12,400 mothers are at risk of passing on “faulty mitochondria” to their children. Estimates suggest that 778 births per year present risks of developing a mitochondrial disorder that could lead to “heart and liver disease, respiratory problems, blindness and muscular dystrophy.” Mitochondrial replacement is thus perceived as a method that improves both the reproductive outcome of mothers carrying “faulty mitochondria,” and the overall health and wellbeing of children that would otherwise inherit diseases from having a mitochondrial disorder.
The controversy surrounding mitochondrial replacement presents a familiar dilemma to those within the health sciences community: balancing medical breakthroughs with the new ethical problems they introduce.
Faizan A. Khan is a first year law student at DePaul University College of Law. Mr. Khan graduated summa cum laude from DePaul University with a Bachelor of Arts in Political Science and minor in Economics. He is a member of DePaul's Health Law Institute and will complete his J.D. in 2017.
 The Human Fertilisation and Embryology (Mitochondrial Donation) Regulations 2015, No. 572.
 Ian Sample, ‘Three-parent babies’ explained: what are the concerns and are they justified?, The Guardian, (Feb. 2, 2015), http://www.theguardian.com/science/2015/feb/02/three-parent-babies-explained
 Karla Adam, Mom, Dad, Donor: Britain moves step closer to allowing babies with 3 people’s genes, Washington Post, (Feb. 3, 2015), available at http://www.washingtonpost.com/world/europe/mom-dad-donor-britain-debates-rules-for-three-parent-babies/2015/02/03/f23a3262-ab2f-11e4-8876-460b1144cbc1_story.html
 Sample, supra
 Dina Fine Maron, When Will “3-Parent Babies” Come to the U.S.?, Scientific American, (Feb. 6, 2015), available at http://www.scientificamerican.com/article/when-will-3-parent-babies-come-to-the-u-s/
 Maron, supra.
 Adam, supra.
 Maron, supra.
 Rebecca Jacobson, Why the term ‘three-person baby’ makes doctors wince, PBS, (Feb. 10, 2015), http://www.pbs.org/newshour/updates/term-three-person-baby-makes-doctors-wince/
 Sample, supra.
 Jacobson, supra.
 Sample, supra.
 Jacobson, supra.
 Laura Smith-Spark, UK lawmakers approve ‘3 parent babies’ law, CNN, (Feb. 3, 2015), http://www.cnn.com/2015/02/03/health/uk-ivf-3-person-babies/