Being transgender is no longer considered a mental illness, but the manual does contain a chapter of gender dysphoria, which is a possible effect of gender incongruence (a mismatch between someone's assigned gender and their experienced gender.)
The manual also have an interesting introductory chapter, which presents the gender relevant language of American psychiatry right now.
I am taking the liberty of republishing the revised 2022 introduction to the chapter on gender dysphoria here, as it can serve as useful reminder in a time where all kinds of transphobic activists claim that "science" is on their side.
I have reformatted the text to increase legibility. The headlines are mine.
Note that I do not necessarily agree with the use of all of these terms ("disorders of sex development" should have been binned in the same way as "gender identity disorder"), but all in all I think the APA has managed to develop a terminology that encompasses gender variance in both a scientific and socially respectful manner.
Note also that:
- The term “desired gender” is now “experienced gender."
- The term “cross-sex medical procedure” is now “gender-affirming medical procedure."
- The term “natal male”/“natal female” is now “individual assigned male/female at birth.”
Here's the introduction to the DSM-5-TR chapter on gender dysphoria.
Gender dysphoria
In this chapter, there is one overarching diagnosis of gender dysphoria, with separate developmentally appropriate criteria sets for children and for adolescents and adults.
Biological sex
The area of sex and gender is highly controversial and has led to a proliferation of terms whose meanings vary over time and within and between disciplines. An additional source of confusion is that in English “sex” connotes both male/female and sexuality.
This chapter employs constructs and terms as they are widely used by clinicians from various disciplines with specialization in treating gender dysphoria.
In this chapter, sex and sexual refer to the biological indicators of male and female (understood in the context of reproductive capacity), such as in sex chromosomes, gonads, sex hormones, and nonambiguous internal and external genitalia.
Intersex
Disorders of sex development or differences of sex development (DSDs) included the historical terms hermaphroditism and pseudohermaphroditism.
DSDs include somatic intersex conditions such as congenital development of ambiguous genitalia (e.g., clitoromegaly, micropenis), congenital disjunction of internal and external sex anatomy (e.g., complete androgen insensitivity syndrome), incomplete development of sex anatomy (e.g., gonadal agenesis), sex chromosome anomalies (e.g., Turner syndrome; Klinefelter syndrome), or disorders of gonadal development (e.g., ovotestes).
Gender
Gender is used to denote the public, sociocultural (and usually legally recognized) lived role as boy or girl, man or woman, or other gender. Biological factors are seen as contributing, in interaction with social and psychological factors, to gender development.
Gender assignment refers to the assignment as male or female. This occurs usually at birth based on phenotypic sex and, thereby, yields the birth-assigned gender, historically referred to as “biological sex” or, more recently, “natal gender.” Birth-assigned sex is often used interchangeably with birth-assigned gender.
The terms assigned sex and assigned gender encompass birth-assigned sex/gender but also include gender/sex assignments and reassignments made after birth but during infancy or early childhood, usually in the case of intersex conditions.
Gender-atypical refers to somatic features or behaviors that are not typical (in a statistical sense) of individuals with the same assigned gender in a given society and historical era; gender-nonconforming, gender variant, and gender diverse are alternative nondiagnostic terms. Gender reassignment denotes an official (and sometimes legal) change of gender.
Gender-affirming treatments are medical procedures (hormones or surgeries or both) that aim to align an individual’s physical characteristics with their experienced gender.
Gender identity is a category of social identity and refers to an individual’s identification as male, female, some category in between (i.e., gender fluid), or a category other than male or female (i.e., gender neutral). There has been a proliferation of gender identities in recent years.
Gender dysphoria
Gender dysphoria as a general descriptive term refers to the distress that may accompany the incongruence between one’s experienced or expressed gender and one’s assigned gender.
However, it is more specifically defined when used as a diagnostic category. It does not refer to distress related to stigma, a distinct although possibly co-occurring source of distress.
Transgender
Transgender refers to the broad spectrum of individuals whose gender identity is different from their birth-assigned gender. Cisgender describes individuals whose gender expression is congruent with their birth-assigned gender (also nontransgender).
Transsexual, a historic term, denotes an individual who seeks, is undergoing, or has undergone a social transition from male to female or female to male, which in many, but not all, cases also involves a somatic transition by gender-affirming hormone treatment and genital, breast, or other genderaffirming surgery (historically referred to as sex reassignment surgery).
Although not all individuals will experience distress from incongruence, many are distressed if the desired physical interventions using hormones and/or surgery are not available. The current term is more descriptive than the previous DSM-IV term gender identity disorder and focuses on dysphoria as the clinical problem, not identity per se.
See also: