Families of transgender children on Tuesday asked a federal court to block President Donald Trumps order to end all federal funding or support for healthcare that aids gender transitions for people younger than 19.In a lawsuit filed against the Trump administration in Maryland federal court, the families, who are represented by Lambda Legal and the American Civil Liberties Union, allege that the order discriminates against transgender people and goes beyond Trumps authority as president.The White House did not immediately respond to a request for comment.As a result of the order, the lawsuit said, hospitals across the country have already begun canceling appointments for gender transition treatments.The plaintiffs say their appointments were canceled in recent days by Childrens National Hospital in Washington, D.C., NYU Langone in New York, Boston Childrens Hospital and Childrens Hospital of Richmond in Virginia. The hospitals are not defendants in the case.Trump, a Republican, said in the Jan. 28 order that it is the policy of the United States that it will not fund, sponsor, promote, assist, or support the so-called transition of a child from one sex to another, and it will rigorously enforce all laws that prohibit or limit these destructive and life-altering procedures.Details about how far the order will reach and how it will be enforced were not immediately clear.It directed the U.S. Department of Health and Human Services to take all appropriate actions to end the chemical and surgical mutilation of children. That could include imposing conditions on healthcare providers receiving any federal funds, which virtually all hospitals do.The lawsuit called the order part of a broad and sweeping attack President Trump has launched against gender ideology and transgender people.It followed a previous executive order by Trump banning transgender people from the military, and another stating that the government will not recognize gender identity apart from an individuals immutable biological classification as either male or female.The order on the military has already been challenged by transgender rights groups. The other has been challenged in two separate lawsuits by transgender women incarcerated in federal prisons who face transfer to mens prisons, one of whom has won a temporary restraining order blocking her transfer.Treatments covered by the order include puberty blockers, hormones and surgery provided to patients under 19 for the purpose of gender transition. Such treatments are often known as gender-affirming care.Republicans in more than half of the 50 states have passed laws or policies that ban gender-affirming care for minors, some of which have been blocked or overturned by the courts. A challenge to Tennessees ban has been heard by the U.S. Supreme Court, which has yet to issue a ruling that could determine the legality of such bans nationwide.The administration of former President Joe Biden, a Democrat, supported access to puberty blockers and hormones, though not surgery, for transgender minors. It passed a rule banning discrimination against transgender people in healthcare, which was blocked by a judge last year.The American Academy of Pediatrics has said that gender-affirming care is proven to prevent suicide and improve mental health.Health organizations in some other countries have been more guarded, with the European Academy of Paediatrics calling for more research and a government-sponsored review in England concluding that the existing evidence around youth gender care is weak.Brendan Pierson, Reuters