Why are there not any cures for genetic disorders?

There are "treatments", but since the origin of the disorders are coded into the genes of the individual, there is no feasible way to alter the affected cells. "Gene therapy", which seeks to replace faulty cells with normal or healthy versions, is only now beginning to yield results. Because tampering with genetic material can have unintended or unforeseen consequences, the use of such techniques is strictly controlled and reviewed. (see the Excellent related link)