From @MrsOvertonsWindow linked report:
An audit published in 2002 of the first 124 patients to be seen by the service showed that only 2.5 per cent of those referred had no associated problems.
At that time, a quarter had spent time in care, nearly half had lost one or both parents through bereavement or separation (predominantly the latter), and close to a quarter of those aged over 12 had histories of self-harming and ‘inappropriately sexualised behaviour’.
We don’t know how the thousands of young people referred more recently compare. In the Netherlands, the pioneers of the medical treatment of gender difficulties, young people have to have experienced it from childhood, and, crucially, be psychologically stable, with no other major mental health problems.