Hearing Health Summer 2015 Issue Summer 2015 | Page 23

research

We have
identified
200 genes
to test.

It also may seem surprising that—more than
a decade after the completion of the Human
Genome Project and projects sequencing
mouse, chick, and many other species’
genomic DNA—we still do not know the
exact functions of many of the roughly 20,000
genes, mostly shared, that are found in each
organism. This is partly because teasing out all of their
interactions and biochemical properties is a painstaking
process, and some of the genes exert subtly different
effects in different organs. It is also because the genetic
wiring diagram in different cells is a lot more complicated
than a simple set of “on/off” switches.
All of this sounds a bit dire. Fortunately, we do have
some tools for filtering the data deluge into groups of
genes that are more likely to be top candidates. The first
is to extract all of the information on “known” pathways,