 -- Researchers from the University of Pennsylvania and Johns Hopkins University say that proposed changes to the health care system under President Trump could have a profound effect on people with disabilities, according to an editorial published yesterday in The New England Journal of Medicine.

Of particular concern is how a proposed restructuring of Medicaid could affect Americans with autism and the people who care for them.

Medicaid is the largest health care payer for patients being treated for autism and other developmental disorders and could face an overhaul under proposals currently being debated in Congress. In 2013, Medicaid served approximately 250,000 children with autism, according to the editorial, titled "Care for Autism and Other Disabilities — A Future in Jeopardy." Since 2014 states have been able to opt into expanded Medicaid coverage, which has allowed people with incomes below 138 percent of the poverty line to enroll in the program.

Under the American Health Care Act, also dubbed "Trumpcare," there would be major changes to Medicaid starting in 2020 that will move it away from an entitlement program that can receive open-ended federal funds to a block-grant fund where states would get a per-person amount of money.

“Medicaid is tremendously important in delivering care for those with disabilities,” said Colleen Barry, Ph.D, a co-author of the editorial and chair of the Department of Health Policy and Management at the Johns Hopkins Bloomberg School of Public Health. "We sometimes think about Medicaid as primarily for low income women and children, but when you look at where the dollars go, they tend to go to individuals with disabilities.”

Barry and her co-author say that if Medicaid changes to a block-grant system families may have to bear more of their health care costs out-of-pocket, compromising their access to services essential in the treatment of these conditions.

"Kids with autism, we know, require a variety of different types of services to allow them to do well, and to improve well-being and the ability to live a healthy life, any many of those services are provided through the Medicaid program," Barry said.

Barry says that lower income patients and their families could be disproportionately impacted. The grants transfer more power and flexibility to the states over the care the program provides but usually result in an overall reduction in services, she told ABC News.

AARP, a group that advocates for senior citizens and other older Americans, said that the block grants could result in "overwhelming cost shifts to states, state taxpayers, and families."

"Individuals with disabilities of all ages and older adults rely on critical Medicaid services," AARP officials said in a statement on Tuesday.

Barry and her co-author say that if the coverage of essential health benefits are no longer required under Medicaid, more and more insurance plans will not offer coverage for habilitative and rehabilitative services, mental health services and behavioral therapies. Under the ACA, insurance plans are required to cover these benefits.

They also say that opening up insurance plans for purchase across state lines -- as President Trump and Republicans have advocated -- could affect options for families seeking insurance plans for children with autism.

Since 44 states require fully-insured plans to cover autism-specific behavioral therapies, Barry says that insurers could get around the mandate by offering out-of-state insurance in states where the coverage is not mandated. State governments could also repeal these coverage mandates in order to lower premium costs, Barry said.