World’s First Three-Parent Baby

Scientists used mitochondrial replacement therapy to aid a childless couple who carry a mitochondrial DNA mutation, resulting in the first ever 3 parent baby.

Highlights

Scientists utilized Mitochondrial Replacement Therapy that was used to deliver a healthy baby boy.
The experiment was aimed at eliminating inheritance of mitochondrial DNA mutation.
Some sections of the scientific community laud the experiment as a significant step in embryology.

Scientists have made it possible for a baby to be born using DNA from two mothers and one father. This is the first time ever that this technique has been employed for the delivery of a healthy baby from a parent who carried mitochondrial mutations.

The technique is approved in the UK but the U.S based team that conducted this experiment had to go to Mexico to circumvent the legislations in the U.S. This, however, is considered a significant step in embryology that could help many mothers with mitochondrial disease to deliver healthy babies.

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Mitochondria are cell organelles that play an important role in generating the energy that cells need to survive.

‘Mitochondrial replacement therapy could prevent transfer of mitochondrial DNA mutation to the offspring’

Dr. John Zhang and colleagues from the New Hope Fertility Centre New York are set to release the full details of the experiment later in October. Dr. Zhang plans to monitor the baby to ensure that it is well and that the technique is not only effective but safe for the baby. “We’d love to do it with partners around the world, and reach out to more families that might need help,”he added.

The Couple in Need

A Jordanian couple have been married for twenty years but they haven’t been able to have a healthy child since the mother had a mitochondrial gene mutation. After 10 years of marriage they delivered a baby girl, in 2005, who was born with a mitochondrial disease called Leigh disease that resulted in the nerves, brain and muscles of the developing infant being affected. The child died when it was 6 years old. The couple had another baby, a boy, who died within 8 months due to the same condition.

US Policy Signals Contradiction on Mitochondrial Replacement Therapy
Scientists believe they can now remove disease-causing mitochondrial DNA from human embryos, providing new cures for previously untreatable conditions.

Facts about Mitochondrial DNA Mutations

Mitochondria are called the ‘powerhouse’ of the cell and they have their own DNA which is independent of the nuclear DNA. They are responsible for 90% of the energy of the cell. The mitochondrial DNA constitutes only 1% of the DNA of an individual and it contains 37 genes.

Mitochondrial mutations can be debilitating in certain conditions leading to severe organ failure.
In adults the symptoms could become worse over time and lead to damage to cells in the heart, brain, liver, skeletal and respiratory systems.

There is a need to safeguard against passing on these genetic mutations to the next generation to avoid complications associated with mitochondrial diseases in the offspring. This will spare the child as well as the parents a lot of trauma.

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An improved method of transferring DNA between human egg cells, a technique that aims to create embryos free of their mother's genetic defects has been unveiled.

Mitochondrial Replacement Therapy

This technique involves

Taking a donor egg and removing the nuclear DNA
Removing the nuclear DNA from the mother’s egg.
Adding the nuclear DNA of the mother to the donor egg
Fertilizing the donor egg that has the mother’s nuclear DNA with the sperm from the father.
The fertilized egg that develops into a healthy embryo is then transferred to the mother to continue development in the womb.

In the technique used by Dr. Zhang and colleagues, the mother carried the developing fetus for 37 weeks and delivered a healthy infant. However, the scientists still need to study if the child is disease free and was able to circumvent the genetic mutation carried by the mother in the mitochondria.

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Mitochondrial disorders are a chameleon-like set of diseases that take many different forms and vary widely from individual to individual.

Controversial Turn of Events

Though a section of the scientific community lauds the efforts by these scientists, this study has raised alarm bells as some scientists question the ethical aspects of this study. The director of the Human Genetics Alert which is a watchdog group, Dr. David King said about the study "It is outrageous that they simply ignored the cautious approach of US regulators and went to Mexico, because they think they know better. These scientists have used an experimental technique that many scientists still think is unsafe in order to create a world first.”

However, Dr. Zhang and colleagues have maintained that they have followed strict ethical practices that include allowing only a male fetus to grow till term as females could transfer faulty mitochondrial DNA to their offspring while a male cannot.

This study will allow more than 4000 women who suffer from mitochondrial disease to have disease-free children if the study proves successful. This trial should not be confused with the development of ‘designer babies’ that are aimed at creating a better ‘breed’ with specific physical attributes. The current experiment was aimed at eliminating a life threatening condition and to allow a childless couple to have a healthy child of their own, how far the scientists have been successful remains to be watched intently.

References:

ABOUT UMDF - (http://www.umdf.org/site/c.8qKOJ0MvF7LUG/b.9166823/k.2E25/Mitochondrial_Replacement_Therapy.htm)
3-Person IVF - (http://www.geneticsandsociety.org/article.php?id=6527)

Source-Medindia