A bipartisan group of Congressional leaders is asking the Department of Health and Human Services to clarify guidelines regarding organ transplants to people with disabilities.

Thirty members of the House of Representatives signed the letter, which was dated Oct. 12. The letter expressly states that people with developmental or intellectual disabilities should not be denied organ transplants solely based on their disabilities.

The letter was prompted by several high-profile cases where a person with a disability was denied a transplant. The letter also cites statistics showing many transplant centers factor a patient's disability into the decision to approve a transplant. A 2008 survey found 85 percent of pediatric transplant centers consider neurodevelopmental status in their eligibility determination at least some of the time.

On Nov. 23, lawmakers in Massachusetts sent Gov. Charlie Baker a bill that would prohibit denying an organ transplant based solely on someone's mental or physical disabilities. Baker has not indicated whether he will sign the bill into law.

Transplant centers say people with disabilities may not be capable of following complex post-operative care instructions, thus risking the chance for a successful transplant. However, the letter cites multiple peer-reviewed studies that show people with disabilities who have a support network in place are no less likely to have a successful transplant than normally developing people.

In the letter, lawmakers called denying organ transplants to people with disabilities a form of discrimination that violates the provisions of the Americans with Disabilities Act of 1990. It further asked HHS Secretary Jocelyn Samuels to direct transplant centers to assess patients' support networks when making eligibility determinations.

"This is discrimination that has life or death consequences," said U.S. Rep. Mike Honda (D-Calif.), who worked with Rep. Jaime Herrera Beutler (R-Wash.) to spearhead the effort to reach out to HHS. "Such discrimination directly violates the Americans with Disabilities Act and does not abide the American values of fairness and inclusion that we hold so dear as Americans, for all our communities."

An HHS spokesperson said the department plans to investigate the issues raised by the lawmakers and respond to them directly.

This is the not the first time HHS has been called upon to clarify guidance on the issue. In 2012, 14 disability advocacy groups petitioned HHS for the same reasons. Also in 2012, an autistic man named Paul Corby was denied a heart transplant by the Hospital of the University of Pennsylvania. His mother started an online petition which amassed thousands of signatures.

The Corby family was inspired by a New Jersey family who were denied a kidney transplant due to an intellectual disability resulting from Wolf-Hirschhorn syndrome. Chrissy Rivera started an online petition to persuade the Children's Hospital of Philadelphia to reverse its decision, which it ultimately did. Rivera donated a kidney to her 3-year-old daughter in July 2013.

Earlier this year, Lily Parra, an infant who needs a heart transplant, was denied one due to the potential that she might have an intellectual disability due to hydrocephalus. Her parents also lobbied Loma Linda University Hospital and started a petition that had garnered more than 100,000 signatures. However, she has not been added back to the list.