Dr McHugh is the former psychiatrist-in-chief for Johns Hopkins Hospital and its current Distinguished Service Professor of Psychiatry. His claims about transgenderism can be summarised:

• Transgenderism is a mental disorder requiring treatment
• Sex change is biologically impossible
• People promoting sexual reassignment surgery promote a mental disorder
• The suicide rate among transgender people who have undergone gender reassignment is 20 times higher than the rate among non-transgender people
• 70%-80% of children who expressed transgender feelings lost those feeling over time
• The idea of sex misalignment is mistaken. It does not correspond with physical reality
• Surgical intervention can lead to grim psychological outcomes

See link:
John Hopkins’s Psychiatrist: Transgender is ‘Mental Disorder’; Sex Change Bilogically impossible