World’s First Three-Parent Baby Born Using Mitochondrial Replacement Therapy

Mitochondrial replacement theory could let parents eliminate fatal genes. Image credits: Getty images
THREE-PARENT BABY

Doctor John Zhang with his team from the New Hope Fertility Centre, New York has successfully created a three-parent baby by mixing DNA from three people using mitochondrial replacement therapy (MRT).

MRT is a novel technique for transferring nucleus taken from mother’s egg into the cytoplasm of donor’s egg lacking the nucleus. Zhang’s team applied this technique to help a 36-years old woman carrying Leigh syndrome to conceive a healthy child.

Mitochondria, the ‘power house’ of the cells provide most of the metabolic energy needed for the survival. Mutations in mitochondrial DNA (mtDNA) can lead to many fatal diseases, including Leigh syndrome.

Genetically, mtDNA is inherited only from the mother by the mechanism of selective parental mitochondrial elimination (PME). Thus making the offspring vulnerable to receive mutated mtDNA from their mother.

In such condition, successful MRT brings hope for women with faulty mitochondria to have disease-free next generation.

HOW DID THEY DO IT?

To create a genetically modified egg, Zhang’s team selected compatible healthy eggs. These were determined by experimentally ruling out the possibility of any pre-existing mtDNA mutation in donor’s egg.

The team then carried out the in vitro fertilization (IVF) of modified egg with father’s sperm. It was then implanted into the mother’s uterus. The whole experiment turned into success with the delivery of a healthy baby boy. The world’s first three-parent baby was born in April 2016.

Three-parent baby mechanism by pronuclear tranfer
Pronuclear transfer technique used in mitochondrial replacement therapy. Image credits: Human Fertilization and Embryology Authority Report, Andy Greenfield. 2014.

Scientists feel that some of the mutated DNA might have passed on to the baby. Surely, this may have a crucial impact on baby’s health in long run. However, the parents of the child denied any more experiment on baby’s mitochondria unless there is a medical need.

MRT- HOPES AND CONCERNS

In order to promote MRT and its benefits, several awareness campaigns have been carried out. Recently in 2013, public consultation program led by the Human Fertilization and Embryology Authority gained a lot of support for the technique.

Moreover, an expert committee assigned by the Institute of Medicine of the National Academics of Sciences, Engineering, and Medicine to analyze the ethical, social, and policy issues concerning MRT has advised FDA to approve MRT for clinical investigations.

The committee has depicted that to avoid ethical, social, and policy issues related to MRT, one needs to understand the difference between the induction of heritable genetic mutation by MRT and elimination of heritable mutation by MRT.

Mixed response came from the scientists and medical practitioners worldwide regarding the benefits and ethical consideration of the present success.

Dietrich Egli from the New York Stem Cell Foundation has described it as a landmark study. He believes, “The parent’s refusal of any further participation may limit the long-term scientific outcome of the study as the scientists cannot monitor the long-term development of the child.”

However, Alta Charo from the University of Wisconsin- Madison, have raised a question on the ethical declaration of the study. She feels, “it is necessary to provide the parents with in-depth information about the importance of conducting long-term follow-up in order to benefit the child and science.

While Dusko Ilic feels that the breakthrough was important, but some questions remain.  Moreover, he questions by saying: “Was this the first time ever they performed the technique or there were other attempts and they are reporting this one because it was successful?

Whatever may be the hopes and concerns, it sure is a shining beacon to thousands suffering from defective mitochondrial DNA.

Read more here.

Source UMDF Elsevier

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