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It is tempting to think
that once the full sequence, or code, of an organism's genome
is known, scientists will immediately understand all the inner
workings of that organism. The reality is that, although scientists
may be empowered, they are not yet enabled. They must still locate
all the functional genes in the genome, determine what products
they make, and learn what those products do. 
Their situation is in many ways similar to having all of the words
of a foreign language written in a list but without spaces, punctuation,
or definitions. Being able to see the letters-or even the words-is
only the beginning. Fundamentally, the job of research must now
shift from one of gathering data to one of understanding it.
It is also
important to recognize that the term the human  genome
is somewhat misleading, because there is no single genome sequence
that defines everyone. No two humans other than identical twins
share identical genomes. For the rest, although the genomes are
more than 99% identical, each is unique. The recently published
human genome sequence that has been posted on the Internet as
a public database, is but one "flavour" of normal. The DNA
that
was sequenced in the project was derived from real people, and
real people, even though they are healthy, carry hidden in their
genomes not only many neutral polymorphisms,
or base sequence variations, but also potentially serious recessive
mutations masked by dominant counterparts. Thus, it is likely
that some of the sequences currently published as "normal" are,
in fact, not. Clearly, a comparison of sequences derived from
a spectrum of healthy individuals will be needed to determine
what should be included in the normal range.
Leslie
Gornstein
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