Biology Reference
In-Depth Information
genes has many possible uses, including the determination of potential drug targets,
the use of a gene itself as a therapeutic agent (gene therapy), controlling the expres-
sion of a gene, and using a gene product as a protein therapeutic.
Private investments necessitated a means to stake claims in this territory, which
have taken the form of patents or trade secrets. These claims necessarily changed
the complexity of research, altering the rules by which materials and data were
exchanged. The seriously conflictual nature of this issue came to the surface in
the international controversy provoked by US patent applications on thousands of
human DNA sequences filed by the National Institutes of Health in 1991, where
opponents to these applications made ethical claims about direct links between
human genes and human dignity (United States Congress
1994
).
It is evident, however, that DNA is a universal genetic code, and it will be dif-
ficult, if not impossible, to distinguish human genes from those derived from other
organisms. While it is obvious that the human genome in aggregate contains the
instructions for creating a human - instead of a monkey or nematode or yeast - it is
equally clear that very few, if any, genes are exclusively human in origin. A classic
1975 paper by King and Wilson showed that the average protein sequence differed
by only 1% between humans and pygmy chimps and the difference at the DNA
level was only slightly greater than 0.3938% (King and Wilson
1975
). The obvious
implication is that humans differ more in the parameters of gene expression than
in the genes themselves. Furthermore, with the advent of human-animal, human-
microbe and human-plant chimeric proteins, which involve creating synthetic
genes combining genetic material from humans with that of other species, these
distinctions become extremely difficult to delineate on a purely practical basis.
These increasingly molecular-based approaches have made target-based drug
discovery easier than was the case with the traditional
in vivo
approach. This is
not surprising, considering the superiority of molecular approaches in screening
capacity and the ability to define rational drug discovery programmes. In part,
these ideas have helped to re-evaluate the enormous costs involved in the drug
discovery process and have streamlined the strategies being employed by pharma-
ceutical and biotechnology companies. Constantly improving genomics technolo-
gies, such as ribonucleic acid interference, have satisfactorily validated targets that
would have taken much longer (and cost more) with traditional transgenic tech-
nologies. Drug targets identified by these techniques involving human genetic
resources could end up being the basis for drug discovery programmes using mol-
ecules isolated from plant sources (Table
7.3
).
Molecular diagnostics is the fastest growing segment of the
in vitro
diagnostics
industry. In little more than a decade, the clinical market for molecular diagnos-
tic products has surged from US$50 million to over US$1 billion in the United
States, and it is likely to reach US$35 billion globally by 2015. These astonishing
exponential figures are an indication of the profitability of the molecular diagnos-
tics market. A major proportion of this may be attributed to advances in genetics,
genomics and proteomics. Driven by perceived commercial benefits, pharmaceuti-
cal companies are increasingly interested in developing tests that can eventually
be used to individualize the prescription of their drugs (Mancinelli et al.
2002
).
