Or. William 6artland 
Page three 
Another possible argument Is that this gene transfer research 
might create monsters. The probability of doing so by this means 
seems no higher than the natural rate. There are a number of 
developmental defects that appear as "monsters" which arise In both 
animal and human populations. Furthermore, defects In endocrine 
function occasionally occur In natural populations which give rise 
to giantism or acromegaly. The large mice that we have created by 
transfer of growth hormone genes Into mice are certainly not 
monsters because they are normally proportioned and they are no 
larger than mice of some other strains. In addition. It Is 
Important to remember that conventional breeding techniques can 
produce extreme variations In size and form. Consider, for example, 
the domestic dog. A Saint Bernard must appear as a monster to a 
chihuahua. 
In contrast, the benefits of gene transfer amoung mammalian 
species are great. The primary emphasis of most laboratories 
Involved In this research Is aimed at understanding animal 
development and gene regulation. The coordination and regulation of 
gene expression during animal development and differentiation are 
major problems that can now be addressed by gene transfer Into 
animals. We are already gaining Important Insights Into the signals 
that determine In which cells a particular gene will be expressed. 
We are also learning more about growth control In animals and the 
endocrine feedback mechanisms Involved. In addition, we are 
learning how the Immune system Is regulated during development. 
These are but a few of the fundamental areas under Investigation. 
They will lead to a better appreciation of developmental processes 
and will allow new Insights Into how these processes go awry In 
human Illness. 
It Is also possible to deliberately mimic a human genetic 
disease In experimental animals, thus providing a valuable model 
system to stimulate research towards ways of ameliorating the 
disease. For example, when genes suspected of being Involved In 
human abnormalities (e.g. Huntington’s chorea) or disease (e.g. 
cancer or arthritis) are Identified, a determination of how they 
work In an Intact animal could provide ultimate proof as well as 
provide a model system for further study. 
1456] 
