THE JOHNS HOPKINS UNIVERSITY 
SCHOOL OF MEDICINE 
DEPARTMENT OF 
MOLECULAR BIOLOGY AND GENETICS 
725 N. WOLFE STREET 
BALTIMORE, MARYLAND 21205 
October 17, 1984 
Dr. William J. Gartland, Jr. 
Executive Secretary 
Recombinant DNA Advisory Committee 
Building 31 , Room 3B10 
National Institutes of Health 
Bethesda, Maryland 
Dear Dr. Gartland: 
I am writing concerning the proposals for prohibition of experiments 
involving mammalian interspecies germ line gene transfer, as described in 
the Federal Register of September 20, 1984. Experiments of this kind are 
likely to be of increasing importance in studying growth and 
differentiation, in developing models of human disease, and in animal 
breeding. Sometimes these experiments will require genes from a species 
different from the recipient or partially or entirely synthetic genes. 
Therefore one should have a very good reason to prohibit experiments of 
this kind. In my opinion, the arguments for prohibition lack merit. I 
don't see how transfer of one or several genes into the germ line of 
experimental animals would threaten the "biological integrity" of the 
species. I urge the Recombinant DNA Advisory Committee to reject both 
proposals . 
Sincerely 
Daniel Nathans 
DN/dhw 
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