Bioethics Blogs

Thruple Babies: Born of 3 Parents

by Craig Klugman, Ph.D.

If a thruple is a three-person relationship, then would their combined genetic child be a thruby?

A baby boy born in April  is believed to be the first child created from the DNA of three parents: mother, father, and egg donor using the spindle nuclear transfer technique. Despite the claims of the media, this is not the first child born with three genetic parents.

Mrs. Y is a carrier of the genetic mutation for Leigh syndrome, is a fatal neurological disease usually diagnosed in a child’s first year. The gene for the disease resides in the 37 genes of the mitochondrial DNA of the cell. The mitochondria live in the cell, but outside of the nucleus that houses most of an organism’s DNA (another 20,000 genes). Mitochondria and their DNA are always inherited from the mother.

After 4 miscarriages and two children dying of Leigh syndrome, Mrs. Y sought the help of John Zhang, and infertility specialist in New York. If the problem was the mitochondrial DNA, the solution would be to use a donor’s egg (for cytoplasm and mitochondria) and exchanging the donor egg’s nucleus for the nucleus from one of Mrs. Y’s oocytes. This is a process called spindle nuclear transfer. Then the father’s sperm is used to fertilize the hybrid egg. This way the child would have both the mother and father’s DNA, but the mitochondrial DNA comes from a third source, the egg donor.

If this sounds familiar, that’s because in February, the United Kingdom announced ethical and legal approval for creating three-person embryos.

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.