WASHINGTON — One immigrant went to California as a child to participate in a drug study that has helped Americans survive with a rare genetic disease. Another, an adolescent girl from Spain, was told by a cardiologist that she must remain in Boston to receive critical care for which her family borrowed thousands of dollars. A teenage boy with cystic fibrosis arrived in the United States “literally dying,” he said, but now has a new lease on life.

On Wednesday, the immigrants told a House Oversight subcommittee why it was imperative that they remain in the country, despite the Trump administration’s abrupt elimination of a program that had enabled them to receive lifesaving medical care without the fear of deportation.

The fate of the immigrants, who all came to the United States legally, remains unclear more than a month after they were first informed by letter that they would have to leave — only to be told early this month that the government would reconsider.

“If I’m sent back, I will die,” Maria Isabel Bueso, 24, of Guatemala, told lawmakers on Wednesday. At three feet tall, sitting in a wheelchair, she was a sympathetic witness.