DSM
The Diagnostic and Statistical Manual of Mental Disorders (DSM) is a guidebook for mental health professionals, providing descriptions, symptoms, and criteria for diagnosing various mental disorders. Published by the American Psychiatric Association, it's widely used in the US and other parts of the world.
I personally think it oversimplifies human emotions and experiences, is influenced by cultural biases.
Transgenderism and being gay used to classified as Mental Illness.
I feel that systems of people and society are best served by Removing unnecessary elements such as this belief system.