A Jordanian couple that previously lost two children to Leigh syndrome, a disorder that breaks down the central nervous system and causes early mortality, gave birth to a healthy baby boy 5-months ago. The success thus far is attributed to Mitochondrial Replacement Therapy, where the nucleus of the biological mother's egg replaces the nucleus of a healthy donor's egg and is then fertilized by the biological father's sperm. The result is a child with the genetic attributes of the biological parents, but without the offending mitochondrial DNA that causes the syndrome.
The genetic modification and insemination was performed in Mexico by Dr. John Zhang of New York's New Hope Fertility Center. This type of procedure is not legal in the US or Canada, but Dr. Neal Sondheimer of SickKids Hospital in Toronto hopes that the sustained health of this child could trigger a reconsideration of the 2004 laws governing reproductive cloning.