if you are really lucky, some of the point-mutations may change
restriction enzyme cleavage sequences. You might consider trying to cut
your samples with a range of restriction enzymes, and looking for
different cleavage fragments. This seems unlikely, however.
Since your gene is only about 5kb, you might just have to sequence it
(or highly variable/interesting parts of it)
sorry I couldn't help more
Rgds Jan Liphardt