Sexual identity disorder or gender deformity is marked on one hand by an intense desire of the individual to belong to the other sex, and on the other by an intense discomfort of the individual for his anatomical sex.

The frequency of gender identity disorder ranges from 0.03% to 3% in boys and from 0.01% to 1.5% in girls and a prerequisite for this diagnosis is to exclude any anatomical or biological disorder. According to the American Psychiatric Diagnostic and Statistical Manual of Mental Disorders (DSM-V) for this diagnosis, at least two of the following criteria are required for at least six months in adolescents or adults:

• An intense desire for the person to fall into the opposite sex
• An intense desire to treat a person as a gender different from the assigned gender
• Significant inconsistency between a person's surviving or sex and sexual characteristics
• Intense desire for the sexual characteristics of a sex other than the assigned sex
• Intentional desire to disqualify a person's sexual characteristics due to disagreement with the person's lived or expressed sex
• A strong belief that one has the typical reactions and feelings of a sex different from the assigned gender

In addition, the condition should be accompanied by clinically significant discomfort or dysfunction.

The treatment of this disorder aims to provide targeted help to the individual to gain greater sexual equilibrium and a sense of pleasure with regard to his own gender identity. This may concern his everyday life, for example dressing and living like the sex she wishes to be. Or, in other cases, may involve systematic hormone therapy in order to change her appearance.

In some of the most radical solutions, the change attempt may involve surgery that will permanently change the anatomical sex. It is also very important to provide extensive long-term clinical assessment and counseling from a mental health professional. In this way the person will feel safe, will be psychologically prepared for this change and will understand the extent to which his personal change is to be desired.