No thats not true, the DSM 5 actually changed the diagnosis from "gender identity disorder" to "Gender dysphoria". Its still listed in the DSM 5, but thats because it would be extremely difficult for trans people to get medical treatment if it wasnt. They removed gender identity disorder from the DSM 5 because gender identity is a form of human variation that can sometimes require medical attention, compared to a psychiatric disease. By shifting from GID to dysphoria, it basically acknowledged that transgender people are NOT mentally ill by default, because gender dysphoria is not present in all transgender people. A trans person can alleviate/cure dysphoria by going through a succesful transition(whether its social/psychical or both). So at the end of the day, the change from "identity disorder" to "dysphoria" basically acknowledges one thing......that trans people are people, and not a bunch of mentally ill freaks. Its possible for a trans person to be just as mentally healthy as a typical cisgender person, if they live in an accepting environment that doesn't treat them like mentally ill freaks or a burden on society.