A working group for the World Health Organization (WHO) has published recommendations to remove categories for mental health disorders based on sexual orientation from an upcoming revision of the International Classification of Diseases (ICD).

The group of international medical experts has recommended to the WHO that the F66 categories, which include conditions relating to uncertainty over or unhappiness with sexual orientation or gender identity, “should be deleted in their entirety” from the next edition of the ICD.

The ICD, which has as its full title the International Statistical Classification of Diseases and Related Disorders, is due to be published in its eleventh revision in 2017. Its tenth edition (ICD-10), which was published in 1990, removed homosexuality as a disorder in itself, but contains the five F66 disorders.

Sexual maturation disorder (F66.0), is defined as: “The individual is uncertain about his or her gender identity or sexual orientation, which causes anxiety or depression.” It is therefore particularly applicable to adolescents first questioning their sexuality.

Ego-dystonic sexual orientation (F66.1) can be diagnosed when “the gender identity or sexual preference is not in doubt but the individual wishes it were different because of associated psychological and behavioural disorders and may seek treatment to change it”.

Regarding supposed treatments for ego-dystonic sexual orientation, the group noted: “Therapies aimed at changing a person’s sexual orientation have been deemed outside the scope of ethical practice.”

Such therapies have been a particularly hot topic in the US recently. Last month, a campaign was launched to end conversion therapy in the States in the next five years.

In Texas, Republicans have adopted a controversial state platform endorsing such therapy, while the Supreme Court has just thrown out an appeal against California’s ban on the therapy.

The WHO working group report explains that, “although F66 categories mention gender identity, historically the categories emerged from earlier classifications of sexual orientation”. Other categories under consideration were F66.2 (sexual relationship disorder), F66.8 (other) and F66.9 (unspecified).

The recommendations to remove these categories come after the working group “found no evidence that [these categories] are clinically useful” and explained that “these categories may create unnecessary harm by delaying accurate diagnosis and treatment”.

“From a human rights perspective,” the report continues, “the F66 categories selectively target individuals with gender nonconformity or a same-sex orientation without apparent justification.”

Following the publishing of these recommendations, the report was peer reviewed by a variety of additional experts including some from countries which criminalise homosexuality. Geoffrey Reed, senior WHO project officer for these revisions, told Science: “None of the peer reviewers tried to make a case that these categories should be retained”.

Nevertheless, the recommendations must still be approved by health ministers from the WHO member states, of which there are currently 194, before the changes can be made.