ABSTRACT
Gender identity disorders (GID) or transsexuality have been a latent issue in Chile 20 years after the first sex reassignment treatment in 1973. Sexual minority groups have posed the problem and even present a bill for civil sexual change. Since the nineties, the number of consultants due to gender identity problems has increased steadily, including children and adolescents. The lack of medical expertise in the area, requires urgent training programs. The first part of this manuscript will deal with the definition, epidemiology, etiology and role of the endocrinologist in the process of sexual reassignment among patients with gender identity disorders. We review sexual differentiation, brain sexual dimorphism and Sexual Development Disorders (SDD) aiming to understand the neurobiological causes of GID and to perform a better differential diagnosis with Sexual Development Disorders. GID are not a psychiatric disease. However the suffering caused by stigmatization, exclusion andabuse generate emotional problems (gender dysphoria). SDD has a genetic and hormonal basis in most cases. Its clinical expression at birth can cause an erroneous civil sex assignation or a discordant civil sex with the sexual identity of the person when there is a surgical correction. GIS without gender dysphoria was excluded as a mental disease from DSM-V and it will also be excluded from the eleventh version of the international classification of diseases. It will maintained as a condition that should be differentiated from SDD and whose treatment should be financed by health systems.