The USPTO is a good source for those information. Many
comments have been made and published on the topics.

Many advocating against granting broadly applicable
patents on the discovery of the "function of some
DNA sequences", as you described. However, utility
patents can be granted to specific technique of
"gene engineering" based on the discovery of certain
functions of a specific DNA sequence.

Such controversy is similar to that on the software
patent. One should not be allowed to patent broad
software features such as "one-click check-out",
the infamous Amazon patent, or "playing with
your pet with a laser pointer", another frivouslous
patent granted. One can be granted patent on techniques
on how to make a scalable system that
support the one-click feature, or a specific design
of pet toy built on the knowledge that cat likes
the red dot a laser pointer made.