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