Three Parent Baby? Can a Human have the genetic makeup from 3 people? When a child is born, that child will have a set of DNA from both of it’s parents. A child being born with three sets of genetic material, DNA, is unheard of - until now.
A 6-month old baby boy was just born in Mexico using a controversial new technique under the care of Dr. John Zhang, the founder and CEO of a fertility center called New Hope Fertility Center in New York. This child has been dubbed the “three-parent baby”, a technique used for preventing mitochondrial diseases from passing on to the infant child in-vitro.
The Mitochondria is a cellular organelle, which among many things, is responsible for generating energy. These organelles are fragile and a mutation on any one of the 37 genes housed inside the mitochondria can lead to fatal inherited diseases, specifically in the brain and muscle, which both require a lot of energy.
The controversial procedure extracts chromosomes from the egg of the mother and implants them into the egg of another mother. This process avoids the parental mother's mutated mitochondrial DNA from being passed down to the child.
This successful mitochondrial DNA transport marks decades of research into the prospect of manipulating the mitochondria to produce healthy eggs in order to overcome fertility problems.
Another controversial technique, also halted by regulation, involving mitochondrial material was pioneered by a NJ doctor in the late 1990s. Cohen and colleagues at Saint Barnabas Medical Center in Livingston, N.J., were looking for a way to help patients unable to have children by In Vitro Fertilization (IVF). The couples’ embryos did not develop normally for unknown reasons. Cohen and colleagues thought a dose of cytoplasm, the jellylike “guts” of a cell, from a donor egg might give the embryos a better shot at success. He extracted 10 to 15 percent of the cytoplasm from a donor egg and injected it along with a single sperm cell into a recipient egg. From 1996 to 2001, he performed the procedure 37 times, producing 17 babies for 13 couples.
Cohen doesn’t know whether mitochondria or other cytoplasm components played a role in producing the children. He will soon publish a study reporting on the health of some of the children, who are now teenagers.
Cohen’s group stopped performing the technique in 2001 because of regulatory issues.
Though this procedure is controversial, it’s proven to be successful in specific cases for struggling parents.
The technique used to produce the baby boy born in April is called spindle transfer. When a dividing cell divvies up its chromosomes, they are attached to protein fibers called microtubules or spindles.
The transplant technique starts with two unfertilized egg cells, one from the donor and one from the mother. In both cells, the membrane surrounding the nucleus has broken down, but the cell has not yet completely divided. The spindle and its attached chromosomes are removed from the mother’s egg and inserted into the donor egg, which has been emptied of its spindle and chromosomes. Then a sperm cell is injected to the resulting egg to fertilize it.
Though there has been success in a few cases, this procedure has been riddled with debate and disputes. The Food and Drug Administration (FDA) and Congress are displeased with this procedure and have blocked attempts to change its illegal status in the United States. Though Zhang might face serious actions for carrying out this procedure, we are keeping an eye on the developments in this arena.
Read more about Pre-Implantation Genetic Diagnosis, In Vitro Fertilization, IVF with Known Genetic Disorders
Source: Third scientific review of the safety and efficacy of methods to avoid mitochondrial disease through assisted conception, Human Fertilisation and Embryology Authority, June 2014
J. Zhang et al. First live birth using human oocytes reconstituted by spindle nuclear transfer for mitochondrial DNA mutation causing Leigh syndrome. American Society for Reproductive Medicine’s Scientific Congress. October 19, 2016. doi: 10.1016/j.fertnstert.2016.08.004.