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01/22/2017

The Semantics of Therapy

What is therapy? This is one question that should occur to the reader of Jill Neimark’s “Unexpected Risks Found In Replacing DNA To Prevent Inherited Disorders.” In referring to the birth of the baby born of three parents last year, the author names it “mitochondrial replacement therapy”:

Using a technique called mitochondrial replacement therapy, the researchers combined DNA from two women and one man to bypass the defect and produce a healthy baby boy — one with, quite literally, three genetic parents.

Jill Neimark is not alone in this use of the term. Shoukhrat Mitalipov, who has lobbied several nations for funding for such research, and his co-author, Don P. Wolf, make that claim in their 2014 paper, “Clinical and Ethical Implications of Mitochondrial Gene Transfer.” Mitalipov and Wolf state that because the changes produced by mitochondrial replacement techniques are “permanent” and “would be transmitted through generations,” this qualifies as “germline gene therapy.” Therapy, according to the Oxford Dictionary of English, is “treatment intended to relieve or heal a disorder;” its Greek roots mean “healing” and “minister to, treat medically.”

Who, then, is treated therapeutically in “mitochondrial replacement therapy”? Is it the child? When John Zhang formed in the laboratory five embryos, each from three progenitors, only one embryo was transferred to a woman’s uterus. That child, a boy, was born in 2016. Readers are not told the disposition of four of the embryos that were not “normal.” If they were destroyed, one could not say that the mitochondrial replacement was for them therapeutic. If the child born of three parents lives a “normal” life, was the mitochondrial replacement therapeutic for him? From a scientific point of view, no, for he did not exist prior to his conception.

It appears, then, that the beneficiary of the mitochondrial replacement “therapy” is the genome. If this is true, a host of difficulties present themselves. Three of these are

  1. If the “patient” is a genome, to whom does the researcher answer?
  2. What other interventions in the genome will be needed? Who decides? Is there a limit?
  3. If the mitochondrial genome of a child so conceived reverts to that of his nuclear-genome-mother, as Mitalipov in his December, 2016, Nature letter reports as a possibility, then what recourse is possible?

— D. Joy Riley, M.D., M.A., is executive director of The Tennessee Center for Bioethics & Culture.

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