Bioethics Blogs

An Assessment of Mitochondrial Replacement Therapy

By: Alexa Woodward

Last year, a baby boy was born from an embryo that underwent mitochondrial replacement therapy (MRT). MRT was used to prevent this child from inheriting a mitochondrial disease from his mother, specifically infantile subacute necrotizing encephalomyelopathy – a disease that affects the central nervous system and usually results in death within the first few years of life. While controversial, assisted reproductive technologies (ARTs) such as MRT provide prospective parents with additional options and have the potential to improve the quality of human life by preventing disease.

This story is of bioethical interest because this technique results in germline modification, which is the alteration of DNA in the reproductive cells of humans that will be passed on to their offspring. Implementing MRT in humans has consequentially garnered much criticism, from simple health-related implications (such as unknown harms to potential offspring and eugenics concerns) to the futuristic next logical step of scientific intervention; directly editing the nuclear genome.

With MRT, modifications affect the mitochondrial genome (mtDNA), not the nuclear genome. Researchers emphasize the lack of bearing that mtDNA has on personal characteristics and the overall maintenance of “genetic integrity,” especially when compared to using the whole donor egg with an “unrelated” nuclear genome.1 Even so, additional concerns arise regarding the long-term anthropological effects, blurring the distinction between therapy and enhancement, and issues of resource allocation.

Mutations and deletions  in the mitochondrial genome can result in mitochondrial diseases affecting the neurological, musculoskeletal, cardiac, gastrointestinal, renal, and other systems, all of which are incurable.  MRT uses the intended parents’ nuclear DNA in conjunction with a donor’s mitochondria.

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.