Albeit a relatively old phenomenon, transgenderism currently remains difficult to define and understand due to the fact that it is so polymorphous and changing. Indeed, while it may be considered that in continuity with the mediatization of the transsexual phenomenon and of the first cases of Sex Reassignment Therapy (SRT), the transgender phenomenon appeared in the 1970s with certain cases of secondary transsexualism described by Stoller, and with the "first" transgender person, Virginia Prince (Castel, 2003, p. 486 and 491), it is only recently that the American Psychiatric Association (2013, pp. 451-459) and the WPATH 4 (2011, p. 97) have given it a certain recognition in their respective studies.According to the definitions given by these associations of health professionals, transgenderism corresponds first and foremost to a group encompassing all the different forms of gender incongruence (whether or not this incongruence entails distress experienced by the individual, and whether or not there is gender dysphoria). It is "simply" the opposite of cisgenderism 5 , that is, the opposite of the congruence between sex and gender. Thus, according to this broader conception, very diverse issues of identity or of non-conformity of gender may be considered as transgender, such as:• transsexualism with total hormonal and surgical transformation, but also partial (without an operation of sexual reassignment), • intersex conditions with ambiguities of genital organs, • identity-related transvestism, and even in a certain manner:• effeminate men who consider themselves as men,• or virile women who consider themselves as women.