ROCHE INSTITUTE OF MOLECULAR BIOLOGY 
Nutley, New Jersey 07110 
December 13, 1979 
Dr. Donald Fredrickson 
Director 
National Institutes of 
Health 
Bethesda, MD 20205 
Dear Dr. Fredrickson: 
I was surprised to learn recently that the revised 
DNA guidelines, particularly the modifications dealing 
with K-12 host-vector systems, remain in the "proposed" 
category. It was my impression that both the specific 
N.I.H. advisory committee and the scientific community 
in general supported the minimum risk assessment of 
most experiments employing the K-12 system. I hope 
that the guideline revisions will be officially accepted 
and sanctioned as soon as possible. 
Sincerely yours 
Aaron J. Shatkin 
AJS : jh 
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