The result, if you have a transgender child that is not able to transition, is that they go through the wrong puberty and are likely to end up a depressed and dysfunctional adult like me. I became extremely suicidally depressed at age 12, and that depression persisted with no relief whatsoever until I started taking steps to transition at age 24. Of course, not all transgender people become depressed, but the 40% suicide attempt rate is real. Most are depressed because they are stuck living as the wrong gender. If they are able to transition in their teens, that number and other mental health outcomes change to being very close to the general population.
I wish every day that I had been able to go on puberty blockers at age 12 and begin hormones when I was 14 like others get to. My teens and twenties have been completely lost to it, and I am still depressed because of it.