Lab Tests Using Recombinant Components - Biotechnology and Your Health: Pharmaceutical Applications - page 137

DNA PROVIDES CLUES ABOUT COMMON ILLNESSES
Over the last decades, as the human genome was sequenced,
scientists have assembled a vast library of small DNA-sequence
differences that are precisely located within the genome. The
marker sequences were used for the reassembly of the sequenced
pieces of the 3 billion base pairs. Some of these markers are found
within a gene that has changed in people with an inherited condi-
tion. Other markers are just that—small sequence differences that
may not by themselves contribute to an inherited condition.
Depending on their location, they may or may not be inherited
by family members with a known inherited condition. These
small sequence differences are sometimes just the substitution of
one nucleotide for another; for example, a G instead of a C. In
each person's DNA, there are millions of these single nucleotide
polymorphisms , inherited differences among individuals (called
SNPs), in about 1 out of every 1,200 bases.
Scientists are very interested in knowing whether single SNPs or
sets of them could provide clues to common illnesses. Many com-
mon human diseases are thought to be the result of the interaction
of one or more genes with environmental factors such as infections,
pollution, or smoking. Scientists are interested in testing people
with conditions such as heart disease, high blood pressure, cancer,
and autoimmune diseases to see if any set of SNPs is found more
often in those who have one of these conditions than in those
who do not. In the future, using such information and powerful
methods of detecting small differences in the DNA sequence, physi-
cians may be able to determine if a person has an increased risk of
a condition such as heart disease, based on the pattern of markers.
These markers may also provide clues as to who will or will not
benefit from or be harmed by a particular drug. Some people see the
testing for SNPs and other markers and the collection of inherited
differences in databases as potentially valuable, but others are con-
cerned about the collection and possible abuse of such information,