We already have the Human Genome Project, and sequencing costs have improved faster than Moore's Law. Soon everyone will have a copy of their own genome, made possible by companies like 23andMe. This will allow targetted individual therapies to start becoming a reality. In fact they're already emerging as an option, with the first gene therapy in the Western world - Glybera - commercialised this year.
Why would we wait until 2130 before starting to use these? We don't need to "fully" understand the body to "start" implementing gene therapy. We can have a partial knowledge and still achieve great things.
Not everything is due to genetics. I am not a biological determinist. The fact that you have certain genes doesn't mean that you are resistant or you will get to this disease. Environment, life-style- conceptualization of a disease ( how we experience and illness) makes the big part.
Even if we develop some gene therapies we may cure some diseases but not many others who are related to the environment and personal experience.
by the way is 23and me reliable ?