-
2 Germ-Line Dancing: Definitional Considerations for Policy Makers
- Johns Hopkins University Press
- Chapter
- Additional Information
c h a p t e r t w o Germ-Line Dancing Definitional Considerations for Policy Makers Eric Juengst, Ph.D., and Erik Parens, Ph.D. Just as“good ethics requires good facts,”good policy requires good definitions. That is why the larger parts of so many public laws are devoted to the definition of their key terms: it is in those definitions that the policies find their true mission, their real scope, and their actual power. Because of that, of course, it is also in the definitions that many of the hard choices about a policy must be made. In this chapter, we examine the definitional choices that will confront those charged with making one particular kind of policy: policy governing biomedicine’s emerging ability to create inheritable genetic modifications (IGM) in human beings. By policy we mean any official position on the matter , be it institutional, professional, or governmental. For convenience, we will call all those charged with addressing these matters IGM policy makers, whether they do so for a single laboratory, a professional society, or a nation. Their definitional choices are shared, and, we hope to show, the clarification of their choices is far from simple ground clearing.The process of getting clear on just what these policy makers are making policy about, in fact, also suggests some contours of the policy itself. The Definitional Problem The definitional distinction between “germ-line” and “somatic cell” gene therapy has been useful—even crucial—to the early regulation of human gene transfer research. It has allowed policy makers to point out that most of the public’s serious qualms about human gene transfer research lay with the introduction of inheritable genetic modifications, and thus would only be raised by attempts to transfer genes into human germ-line cells.1 To allow the nascent field of gene transfer research to proceed without having to resolve the vexing moral problems that inheritable genetic changes were perceived to raise, it was enough simply to postpone or proscribe all attempts to transfer genes into human germ-line cells and focus our regulatory attention on assessing the safety and efficacy of human somatic cell gene transfer protocols.2 But what techniques and technologies should this distinction hold apart? What should it mean to “transfer genes into the germ line”? For the past hundred years,the IGM policy makers’definitional task seemed relatively simple.In 1885,the embryologistAugustWeismann distinguished between what he called somatische cells and those possessing what he called Keimplasma : the “germ plasm” that allows a sperm and ova to transmit hereditary traits from parents to their offspring.3 Embraced by American embryologists, the distinction between the tissue lineages in a growing embryo that differentiate into its “germ (plasm) cells” and those that differentiate into its other “somatic” cells has long outlived Weismann’s Keimplasma theory of inheritance . Of course, its heyday as a provocative scientific distinction passed with the death of the germ plasm theory, especially after we realized that the structures that do carry out the hereditary function—the genes—are actually alive and well in all types of nucleated human cells. With the continuities between generations explained as the expression of information encoded in multiple,independently assorting genes (later to be understood as recombining DNA molecules ), the“immortal germ plasm”was no longer necessary as a racial“hereditary fluid,” except to the eugenicists who embraced it as their poster child.4 Nevertheless, Weismann’s terminology has remained embedded in developmental histology, where “germinal” language continues to be used as a convention to identify the cell lineages whose progeny will eventually undergo meiosis to produce gametes. Moreover, since its centennial birthday, Weismann ’s somatic/germinal distinction has developed an important second caDe finitional Considerations 21 [54.208.238.160] Project MUSE (2024-03-28 13:19 GMT) reer in science policy, as the cornerstone for our thinking about the limits of human gene transfer research. Fortunately, in its science policy role, the somatic cell/germ cell distinction still does not have to bear much theoretical weight. Although its antiquated language can be confusing, in the context of human gene transfer research it is used simply to signal the fact that only genetic changes introduced into the cell lineages that produce the gametes—the “germ line”—can be transmitted to the next generation, while changes confined to “somatic” cell lines cannot...