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A Pennsylvania woman whose autistic adult son was not recommended for a heart transplant because of his illness and the complexity of the process, among other factors, said she wants to bring more attention to the decision-making process so that those with ailments or disabilities are not passed over without careful consideration.

Karen Corby said Thursday that her son, Paul, now 23, was denied a heart transplant from the Hospital of the University of Pennsylvania last summer over what it said were concerns about his "psychiatric issues" and "autism," among other factors.

One expert on medical ethics said it's legitimate for the mother to raise the point, but there's an even bigger one, too.

"The thing to keep in mind is if more of us would sign donor cards, there would be less pressure to reject anybody. It's the huge shortage of hearts that really drives this problem," said Arthur Caplan, head of the Division of Medical Ethics at New York University's Langone Medical Center.

Paul Corby was recommended for the procedure because he was born with left ventricular noncompaction, a congenital disorder that left part of his heart less able to pump blood through his body. He was diagnosed with the ailment in 2008. He was referred to Penn Medicine in 2011 to discuss a transplant.

In a letter, dated June 13, 2011, Dr. Susan Brozena wrote: "I have recommended against transplant given his psychiatric issues, autism, the complexity of the process, multiple procedures and the unknown and unpredictable effect of steroids on behavior."

His mother said she was taken aback by the decision and noted that her son, who is diagnosed with Pervasive Developmental Disorder, was upset by the decision, but optimistic that a transplant could come.

"He just needs a fighting chance and the same rights to medical care as others his age," she said in a statement. "Autism is not a terminal disease and we cannot allow it to become one."

Mindful of a similar incident in Philadelphia where a New Jersey family's daughter was denied a kidney transplant because of mental disabilities -- a decision that went viral online -- Corby began her own online petition.

"There has been a huge outpouring of support from Autism groups all over the country," she said in an email to The Associated Press, noting that the number of signers has jumped from 1,500 in April to just more than 13,000 on Thursday. "I would not have found the strength to continue fighting had it not been for them."

In a statement, the University of Pennsylvania Health System said it cannot discuss its' patients' cases but noted that "when individuals are referred for transplant consideration at Penn or any other certified transplant center, all aspects of their medical status would be reviewed."

"This includes the current health status and post-transplant prognosis of the recipient, the impact of other existing health problems on the success of the surgery itself and over the longer term, as well as the potential interaction between a patient's existing drug therapies and the drugs that would be necessary to stop transplant rejection," read the statement from spokeswoman Susan Phillips.

"Our criteria for listing an individual for transplant are regularly reviewed in comparison with national standards, but we always encourage patients to seek another opinion."

Caplan said it's appropriate to have a public discussion about the issue, since organs are donated by the general public. But he also said that autism is something that any institution would "absolutely" take into account in deciding eligibility.

"It's not like autism is not relevant," he said, since the term covers a very broad range of symptoms, including some people who have difficulty taking care of themselves.

"You need to be able to complain if you get certain symptoms," he said of a transplant patient, adding that a heart transplant isn't a simple cure, but rather a case of trading a terminal disease for a chronic one that needs long-term monitoring and medication.