In this research work we approach to the knowledge of undiagnosed diseases. These diseases are framed within the so-called rare diseases, because they are not frequent. They generate a series of conditions in the lives of the affected people and in their social relationships. This is the result of the semiotic break between the biological and the social code. This situation can force people with these diseases to be out of the social structure, and they also can be reduced their (...) capacity to make decisions. For this reason, it is necessary to develop semiotics bridges that connect the codes we have talked about. (shrink)