All cells of the early human embryo are totipotent until shortly after the blastocyst stage, including the cells of the inner cell mass and even the primitive
germ-line cells.
Germ-line therapy, performed on early human embryos is more problematic because it alters the basic genetic constitution of the person and all of his or her future offspring.
(5) Highly prominent cultural commentators like bioethicist Leon Kass, (6) political scientist Francis Fukuyama, (7) environmentalist Bill McKibben, (8) and even Sun Microsystems cofounder Bill Joy have begun calling for caution, or even preemptive prohibition of human "
germ-line" genetic engineering (transhumanists label such attitudes "bio-conservatism").
There is little doubt that research into therapeutic human cloning and
germ-line therapies would expand our knowledge of human biology, especially in the areas of preimplantation and developmental genetics.
When inherited changes--we now know that these must be changes in
germ-line DNA--leave some members of a species able to produce fertile offspring amongst themselves, but unable to produce fertile offspring with other members of the same species, then the
germ-line DNAs of the smaller and larger subpopulations will begin to diverge from each other by random mutation.
What about preembryonics, stem-cell research, gene therapy, and
germ-line genetic engineering?
An earlier version of this article was presented at "
Germ-Line Interventions and Human Research Ethics," a conference held on 5 April 2002, at Washington University in St.
I think that when you start messing with
germ-line therapy or
germ-line reproduction, you are talking about making irreversible changes in human genetics, and we have no idea what could happen.
But
germ-line modification, the alteration of DNA in the fertilized egg, is the real Pandora's box.
But in the aftermath of He's disclosure, the scientific establishment is pondering whether it took sufficiently firm actions to discourage
germ-line editing.
What was reportedly done in China is called
germ-line editing.