Last month the United Kingdom became the first country to back three-person in vitro fertilization (IVF), a technique that creates babies using DNA from 3 individuals. This technique is especially controversial because the subsequent genetic alteration to the embryo affects the germline (i.e. germ cells that have genetic information), that will be passed on to future generations, effectively changing the genetic makeup of humanity. While mixing the DNA of 3 individuals may seem very Frankenstein-esque, it is in reality a medical advancement that is specifically targeted to individuals that are genetic carriers of mitochondrial diseases, and risk passing them on to their children.
How can a three-person IVF reduce the risk of mitochondrial diseases in genetic carriers?
Mitochondria are the “energy factories” of our cells that are inherited exclusively from the mother’s oocyte. Each mitochondrion carries its own tiny DNA, which is different from the nuclear DNA that determines features like eye color and personality. In forensic science and ancestry analyses, the mitochondrial DNA is used to trace the origins of the maternal line. If mitochondrial DNA is mutated, some cells cannot produce enough energy, leading to a disease. Mitochondrial diseases are very rare but are devastating nonetheless. Symptoms vary greatly in severity from individual to individual and include poor growth, muscle weakness, and heart disease.
Three-person IVF increases infertility options
Traditionally, couples where the female is a genetic carrier for mitochondrial diseases were limited to 3 options:
- Have another child that could potentially have a mitochondrial disease
- Undergo IVF with an egg donor, and have a child that carried the genes of the egg donor and the male partner
- Not have any more children
With a three-person IVF, this allows a female donor to supply a healthy egg, reducing the risk of mitochondrial diseases in a newborn. The new 3-person IVF technique was pioneered by Prof. Doug Turnbull in Newcastle University and utilizes a donor egg to supply healthy mitochondria. With this technique, these couples can now have a child where all 20,000 nuclear genes would come from the mother and the father, and only 37 mitochondrial genes would come from a donor egg. Mitochondrial DNA primarily contains genes required for mitochondrial functions and not genes that control critical features such as personality and appearance.
Three-person IVF misconception
The misconception that this is generating ‘designer babies’ is simply not true since couples are only selecting to have a baby that does not have a mitochondrial disease. This new fertility treatment will enable women that are genetic carriers of mitochondrial diseases to have their own children, that carry their nuclear DNA, and not the nuclear DNA from a donated egg.
If you would like to learn more about how genetic testing can help with fertility, continue reading this related blog post: “Genetic testing of embryos greatly improves fertility treatment outcomes”.
Author: Antonia Borovina