At the extreme of GID in children are boys who, by the standards of their cultures, are as feminine as the most feminine of girls, and girls who are as masculine as the most masculine of boys. No sharp line can be drawn on the continuum of GID between children who should receive a formal diagnosis and those who should not. Girls with the disorder regularly have male companions and an avid interest in sports and rough-and-tumble play. They show no interest in dolls or playing house (unless they play the father or another male role). They may refuse to urinate in a sitting position, claim that they have or will grow a penis and do not want to grow breasts or to menstruate, and assert that they will grow up to become a man (not merely to play a man’s role).

Boys with the disorder are usually preoccupied with stereotypically female activities. They may have a preference for dressing in girls’ or women’s clothes or may improvise such items from available material when the genuine articles are not available (the cross-dressing typically does not cause sexual excitement, as in transvestic fetishism). They often have a compelling desire to participate in the games and pastimes of girls. Female dolls are often their favorite toys, and girls are regularly their preferred playmates. When playing house, they take a girl’s role. Their gestures and actions are often judged to be feminine, and they are usually subjected to male peer group teasing and rejection, a phenomenon that rarely occurs with boyish girls until adolescence. Boys with the disorder may assert that they will grow up to become a woman (not merely in role). They may claim that their penis or testes are disgusting or will disappear or that it would be better not to have a penis or testes. Some children refuse to attend school because of teasing or the pressure to dress in attire stereotypical of their assigned sex. Most children deny being disturbed by the disorder, except that it brings them into conflict with the expectations of their families or peers.

Children with a gender identity disorder must be distinguished from other gender-atypical children. For girls, tomboys without gender identity disorder prefer functional and gender-neutral clothing. By contrast, gender identity-disordered girls adamantly refuse to wear girls’ clothes and reject gender-neutral clothes. They make repeated statements of being or wanting to be a boy and wanting to grow up to be a man, along with repeated cross-sex fantasy play, so that, in mother–father games or other games imitating characters from the mass media, they are male. This accompanies a marked aversion to traditionally feminine activities.

For boys, the differential diagnosis must distinguish those who do not conform to traditional masculine sex-typed expectations, but do not show extensive cross-gender identification and are not discontent with being male. It is not uncommon for boys to reject rough-and-tumble play or sports and to prefer non-athletic activities or occasionally to role play as a girl, to play with a doll, or to dress up in girls’ or women’s costumes. Such boys do not necessarily have a GID. Boys who do have a GID state a preference for being a girl and for growing up to become a woman, along with repeated cross-sex fantasy play, as in mother–father games, a strong preference for traditionally female-type activities, cross-dressing, and a female peer group.

Because the diagnosis of GID excludes children with anatomical intersex, a medical history needs to be taken, with the focus on any suggestion of hermaphroditism in the child. With doubt, referral to a pediatric endocrinologist is indicated [9].

Similar signs and symptoms are seen in adolescents and adults. Adolescents and adults with the disorder manifest a stated desire to be the other sex; they frequently try to pass as a member of the other sex, and they desire to live or to be treated as the other sex. In addition, they find their genitals repugnant, and they desire to acquire the sex characteristics of the opposite sex. This desire may override all other wishes. They may believe that they were born the wrong sex and may make such characteristic statements as “I feel that I’m a woman trapped in a male body” or vice versa.

Adolescents and adults frequently request medical or surgical procedures to alter their physical appearance. Although the term transsexual is not used in DSM-5 [1], many clinicians find the term useful and will probably continue to use it. In addition, transsexualism appears in the tenth revision of International Statistical Classification of Diseases and Related Health Problems (ICD-10) [32], and such persons refer to themselves as transsexuals.

Most retrospective studies of transsexuals report gender identity problems during childhood, but prospective studies of children with GID indicate that few become transsexuals and want to change their sex. The disorder is much more common in men (1 per 30,000) than in women (1 per 100,000) [9].

Men take estrogen to create breasts and other feminine contours, have electrolysis to remove their male hair, and have surgery to remove the testes and the penis and to create an artificial vagina. Women bind their breasts or have a double mastectomy, a hysterectomy, and an oophorectomy. They take testosterone to build up muscle mass and deepen the voice and have surgery in which an artificial phallus is created. These procedures may make a person indistinguishable from members of the other sex.

Gender identity disorder can be associated with other diagnoses. Although some patients with GID have a history of major psychosis, including schizophrenia or major affective disorder, most do not. When a diagnosis of GID is made, as well as another DSM Axis I diagnosis, it is necessary to consider whether the diagnoses are distinct. A variety of Axis II personality disorders may be found in patients with gender identity disorder, particularly borderline personality, but none is specific. A proportion of nonhomosexual men with GID report a history of erotic arousal in association with cross-dressing, and some would still qualify for a concurrent diagnosis of fetishistic transvestism. Some are more sexually aroused by imagining themselves with a female body or by seeing themselves cross-dressed in a mirror (autogynephilia) than by items of women’s clothing per se.