February 13, 1976

Dr. Eldon Sutton
Departmen€ of Zoology
University of Texas
Austin, Texas 78712

Dear Eldon,

We have been very pleased with your book, "An Introduction to
Human Genetics", and are using it in our (elementary) medical genetics
course.

I also used your Chapter 5 in my course on "Health" and I have to
say that I found page 479 (which I guess follows Swenson in NYAS 1970)
to illustrate a common fallacy in cost-benefit analysis. Namely, you
compare a 30 year cost stream totalling $150,000 with an investment
of $20,000 per Downs @ound. But the present value of that 30 year
stream, discounted at say 6% is only $70,000. So it is still a good
bargain (if anyone doubted it!) - but one should be careful not to
exaggerate. oe

I think the (possible) residual risk of amniocentesis has to be
counted as much as the cost in trying to decide on a reasonable cutoff
age for the marginal benefit; and of course, this also fluctuates with
each family's special perception about the prospective child.

I was sure you would welcome this comment, and I wish you many
succes3ful editions.

Sincerely yours,

Joshua Lederberg
Professor of Genetics

JL/rr

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