President Barack Obama is calling for an end to psychiatric therapy treatments aimed at changing the sexual orientation or gender identity of gay, lesbian and transgender youth.

The move comes in response to an online petition posted on the White House website following the death of 17-year-old Leelah Alcorn. The transgender teen committed suicide in December and left behind writings mentioning religious therapy.

In a statement late Wednesday, White House senior adviser Valerie Jarrett said the administration supports banning so-called conversion therapy treatments for minors.

"We share your concern about its potentially devastating effects on the lives of transgender as well as gay, lesbian, bisexual and queer youth," Jarrett said. "The overwhelming scientific evidence demonstrates that conversion therapy, especially when it is practiced on young people, is neither medically nor ethically appropriate and can cause substantial harm."

The White House is not explicitly calling for congressional legislation to ban the therapies nationwide. But Jarrett's statement highlighted states that have outlawed the practice and expressed hope that there will be broader action.

The White House says lawmakers in 18 states have introduced legislation similar to measures already in place in California, New Jersey and Washington, D.C., banning licensed professionals from using conversion therapy on minors.

The American Psychiatric Association has long opposed conversion therapy, which the organization says is based on the assumption that homosexuality is a mental disorder.

Alcorn, the Ohio teen whose death spurred the White House petition, had gained an online following through her Tumblr posts. She wrote about depression and isolation, lamented that her life would only get worse, and expressed frustration that her parents wanted her to be "their perfect little straight Christian boy." She said she was taken to "Christian therapists" who were "very biased."

Mara Keisling, the executive director of the National Center for Transgender Equality, welcomed Obama's statement.

"Having President Obama and the weight of the White House behind efforts to ban conversion therapy is so critical in the fight for transgender and LGB young people," Keisling said in a statement. "My hope is that when a transgender person's struggle is acknowledged by one of the most recognizable figures in the world, it positively changes the way they view themselves. The pseudo-science that propels conversion therapy cannot match the self-acceptance that comes with this kind of change."