It seems like everyone knows someone who suffers from infertility or who can’t have children because of an inheritable disease. Realizing that the possibility of seeing double lines on a pregnancy test is nearly impossible, may be one of the hardest things someone has to go through in their entire life. Women with mitochondrial diseases are part of those with fertility problems. Luckily, the first steps were set in enabling these women to get pregnant.
On the 6th of April 2017, the first baby with DNA from three different people was born using the mitochondrial replacement theory.[1] This is an in vitro fertilization technique which allows women who suffer from a mitochondrial disease to have healthy children by replacing the faulty mitochondrial DNA with DNA from a donor. [2]
Why only women, you may ask? Well, in sexual reproduction an embryo only inherits mitochondria from its mother. These mitochondria have their own DNA that differs from nuclear DNA. Since mitochondria are responsible for producing energy in a cell, a mutation in one of these genes has a major effect on other organs. So, when a woman is a mitochondrial disease carrier or has it herself, the baby automatically inherits it too.
In theory, there are three methods for a procedure like this, but only one of them is approved: pronuclear transfer. This technique requires the fertilization of two eggs, one from the mother and one from a donor, with sperm of the father. Before the egg starts to evolve into an embryo, the donor’s nucleus is replaced by the mothers’ nucleus. However, since an embryo gets destructed during this method, this goes against a lot of people’s morals. [3]
This is why a different approach, called the spindle nuclear transfer technique, was introduced. Here the nucleus from the mother replaces the donor’s nucleus before fertilization with the father’s sperm. Five embryos were created using this technique, but only one of them developed normally. This embryo was implanted into the mother’s uterus and nine months later a healthy baby was born.[4]
For safety measures, the baby’s mitochondria were tested for possible mitochondrial diseases. Luckily, less than 1 percent of mutated DNA was found. Yet, this does not preclude that the child should be monitored for the rest of its life.[5]
The spindle nuclear transfer technique is wonderful in the sense that it gives women the chance to have children of their own without passing on a disease due to mutations in their mitochondria. However, since it’s still in its early stages, the long-term effects on the child are still unknown.
[1]khttps://cbsebiology4u.wordpress.com/2017/04/15/two-women-one-man-and-a-baby-worlds-first-three-parent-baby/
[2]https://www.nature.com/news/genetic-details-of-controversial-three-parent-baby-revealed-1.21761
[3]https://www.newscientist.com/article/2107219-exclusive-worlds-first-baby-born-with-new-3-parent-technique/
[4]https://www.sciencedirect.com/science/article/pii/S2212066116300345
[5]https://www.newscientist.com/article/2096401-three-parent-babies-might-have-health-problems-in-later-life/
Wordcount: 432 words without the title and the sources
The Biomedical Scientist 