lure, and physical, mental, and emotional character- 
istics are all presumably controlled or influenced by 
vast arrays of genes about which we know little or 
nothing. There are dozens (hundreds?) of genes with- 
in every cell that make regulatory substances used by 
the cell in unknown ways. We do not know what the 
substances are, how they work, or what genes are in- 
volved. Any planned alteration of multigenic traits 
will not be accomplished by gene therapy for many 
decades to come, if ever. 
Conclusions 
We argue that gene therapy for some genetic disor- 
ders will be possible in the foreseeable future. Ethical 
codes 1 ' 10 emphasize that before any experiments are 
performed in human beings, there should be reason- 
able evidence from studies in animals that the patient 
will benefit (or that knowledge that may benefit fu- 
ture patients will be acquired), and there should be a 
reasonable expectation of minimal, or at least accept- 
able, risk. It is our view that knowledge in several 
areas should be obtained from studies in animals be- 
fore gene transfer in human beings is ethically justi- 
fied. Specifically, experiments in animals should dem- 
onstrate that the new gene can be put into the target 
cells and remain in them, that the new gene can be 
regulated appropriately, and that the presence of the 
new gene does not harm the cell. 
We must await a full scientific report of the facts of 
the recently reported attempt to treat 0-thalassemia 
with gene therapy before judgment can be made 
about this experiment. 
We recognize that the urgent desire to treat pa- 
tients having lethal or extremely serious genetic dis- 
eases may lead the attending physician to attempt 
promising, though not fully tested, new regimens. In 
this sense, treatment of a critical illness by gene ther- 
apy differs little from treatment of cancer with a new 
chemotherapeutic agent or treatment of a congenital 
malformation with a complex and dangerous new 
surgical procedure. In each case, the ethical prin- 
ciples governing experimentation in human beings 
apply. The successful application of gene therapy in 
human beings offers the strong possibility of enor- 
mous good by reducing the suffering and death caused 
by genetic diseases. W'e hope that this laudable goal 
Recombinant DNA Research, Volume 12 
will not be jeopardized by premature experiments 
that could prove needlessly ineffective or hazardous. 
National Institutes of Health W 1 Kl M " AnDKKSON, M.l). 
Bcthcvda. MU 20205 Joll.N C. Fl.K ICIIKK, Pll.l). 
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