Gender dysphoria (GD) is the distress a person feels due to their birth-assigned sex and gender not matching their gender identity. People who experience gender dysphoria are typically transgender. Evidence from studies of twins suggests that gender dysphoria not only has psychological causes, but may have biological causes as well.
The diagnostic label gender identity disorder (GID) was used by the DSM until its reclassification as gender dysphoria in 2013, with the release of the DSM-5. The diagnosis was reclassified to better align it with medical understanding of the condition and to remove the stigma associated with the term disorder. The American Psychiatric Association, publisher of the DSM-5, stated that gender nonconformity is not the same thing as gender dysphoria, and that "gender nonconformity is not in itself a mental disorder. The critical element of gender dysphoria is the presence of clinically significant distress associated with the condition." Some transgender people and researchers support declassification of the condition because they say the diagnosis pathologizes gender variance and reinforces the binary model of gender.