Human egg cell about to undergo in vitro fertilization [Image: ‘Oocyte with Zona pellucida’ from ZEISS Microscopy]
Human egg cell about to undergo in vitro fertilization, which can be used to assist with conception or screen for genetic diseases [Image: ‘Oocyte with Zona pellucida’ from ZEISS Microscopy]
A now five-month-old boy was the first child to be born via spindle nuclear transfer, a controversial fertilization procedure that incorporates genetic material from three different people.  Most of our genes are located in the DNA found in a cell’s nucleus, but a few reside in tiny compartments called mitochondria.  While rare, mutations in mitochondrial DNA can result in devastating disorders that often cannot be treated.

Spindle nuclear transfer can prevent mothers from passing along these faulty genes.  After an egg is obtained from a third person that harbors healthy mitochondria, its nuclear DNA is removed and replaced with the mother’s nuclear DNA.  The egg can then be fertilized with the father’s sperm, implanted back into the mother, and carried to term according to traditional in vitro fertilization procedures.  Therefore, the third parent’s contribution is limited to her mitochondria and the smattering of genes that they possess.

Unfortunately, regulatory hurdles and ethical concerns may hamstring the future of this promising technique.  The aforementioned baby boy appears to be 100% healthy, but ethicists and regulatory agencies from all over the world have demanded further evidence of long-term safety before expanding its scope.  Obtaining these data will be challenging, however, because the procedure is currently legal in only a handful of countries.  Furthermore, significant restrictions on human embryonic research make it difficult to perform experiments in the lab that could improve our understanding of human development.  Hopefully our one, pint-sized data point can help to weaken the vicious cycle that’s holding back this important advance in reproductive medicine.

Acknowledgments: Many thanks to Tyler Huycke, a graduate student in the Biological and Biomedical Sciences Program at Harvard University, for providing his expertise and commentary on the topic.

Managing Correspondent: Christopher Gerry

Media Coverage: Exclusive: World’s first baby born with new “3 parent” technique – New Scientist; Birth of Baby With Three Parents’ DNA Marks Success for Banned Technique – The New York TimesWorld’s first baby born with novel three-parent embryo technique – STAT 

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