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SNPs are single nucleotide polymorphisms - ‘snips’. Some
99.9% of the three billion nucleotide pairs in each person’s
genome are the same in everyone, but 0.1% varies between
individuals. These are the SNPs, or variations in single
bases. Such polymorphisms can vary in their effect. They
might have no effect or can simply lead to variations in
hair and eye colour. However, for the pharmaceutical industry
they are of particular interest since SNPs can:
- cause
a fatal disease
- interact
with other genes to produce illnesses
- increase
susceptibility to a disease as a result of environmental
influences
They
are useful markers as they are evenly spaced throughout
the genome, easy to detect, and are stable over many generations.
Studies that look at how such SNP patterns affect disease
susceptibility and drug response are expected to lead to
the development of new treatments.
In
June 1999, the journal Nature Genetics included reports
on two studies involving SNPs and their role in susceptibility
to disease. In one piece of research, 40 Africans and 34
Americans of European origin were used to study 75 different
genes involved in high blood pressure. The team of researchers
found 874 different SNPs, more than half of these causing
a change in the protein controlled by the gene - indicating
a biological effect. The second study focused on SNPs in
106 genes suspected of playing a role in coronary artery
disease, Type II diabetes, and schizophrenia. Subjects of
European, African-American, African Pygmy and Asian descent
were studied, and the researchers found that the majority
of the variations in SNPs had nothing to do with ethnic
background. Scientists believe there could be anything from
240,000 to one million SNPs in the human genome.
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