Engineering Animals With Human Genes

This story is written as if placing human genes in animals is something new. It reports on how UK scientists have engineered mice to contain human genes that are implicated in Down’s syndrome. The point is to help the researchers “identify which gene or genes cause each of the symptoms common to people with Down’s syndrome,” such as heart difficulties and intestinal blockages.

In actuality, such “transgenic” animals have been around for years now. Indeed, before Ian Wilmut cloned Dolly precisely so he could learn how genetically engineer ewes to have human genes so that they would produce proteins that could be extracted from their milk for use in creating pharmaceuticals—a process called “pharming.” At the time Wilmut eschewed engaging in human cloning. But when his pharming enterprise went belly up, following the money, he reversed course and is now engaged in human therapeutic cloning. He has even endorsed reproductive cloning if it becomes safe, at least in some circumstances.

But I digress: The issue, it seems to me, isn’t whether we should create transgenic animals for the study of human disease. As my friend William Hurlbut has put it, these genes are not the locus of human dignity.

But such experiments do raise important questions that urgently need to be—but are not being—addressed: How much human in an animal is too much human in an animal? How do we regulate, if at all, the creation of human/animal chimeras? Should we outlaw placing animal genes into human embryos?

Irving Weissman of Stanford is planning to make a mouse fetus with a human brain. The time for government to engage these issues is long past due, since scientists have shown little inclination to engage in self-restraint.