i>ajety oj retrovirus gene therapy, Temin, 
merits when the new technologies are available. Thus, it seems improper to block in- 
troduction of this potentially useful new therapy because of concerns related to other new 
technologies. For example, successful somatic gene therapy of human disease with 
retrovirus vectors may increase the probability that scientists will try to develop germ-line 
gene therapy of human disease with retrovirus vectors. However, attempts to develop 
retrovirus vectors for germ-line alterations in laboratory and farm animals are popular 
topics for current research (earlier chapters and Temin, 1986b). Thus, this technology will 
exist for non-humans and will have to be evaluated regardless of what happens with 
somatic gene therapy of human disease with retrovirus vectors. 
Any evolutionary effects of this treatment will be small. Some patients that 
would have died may survive to have children who then would have some probability of 
inheriting their mutant gene. However, this would usually not affect the total number of 
mutant genes in the population. As indicated above, even if germ-line integration oc- 
curred, it would have no observable effect. 
IV. Summary 
Somatic gene therapy of human disease with retrovirus vectors is a new technol- 
ogy with potentially important medical benefits. Although it involves recombinant DNA 
technologies and retroviruses, proper design of the vectors and delivery systems can be 
performed to remove most risks. Furthermore, even in the very unlikely possibility there 
was an observable biological effect, it is unlikely to be harmful. Thus, once very safe 
vector-helper cell systems are constructed, safety considerations should not hold up 
human trials. 
Ackowledgements 
I thank J. Dougherty, J. Embretson, M. Emerman, C. Gelinas, T.Gilmore, and R. 
Risser for useful comments. The research in my laboratory is supported by grants CA- 
Recombinartt DNA Research, Volume 1 2 
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