There are nearly 7,000 diseases that are considered rare, meaning they affect less than 200,000 people in the United States.
While each individual disease may be rare, together all of those diseases affect nearly 30 million Americans.
Nine year-old Morgan Doetsch of East China, Mich., is one of those 30 million. She was diagnosed with a rare disease when she was just one day old.
"One-thirty, 2:00 in the morning that night, we were sleeping and a nurse comes in and says to us, 'I just want to let you know, your daughter has PKU,'" said Erin Doetsch, Morgan's mother. "I looked at my husband. It's like, 'What is PKU?'"
PKU stands for phenylketonuria.
In the United States, all babies are tested for PKU as part of their newborn screening. It's a genetic disorder that leaves the body unable to break down an amino acid called phenylalanine.
If PKU is not treated quickly, phenylalanine can build up in the blood and cause mental retardation and other health problems. The main treatment for PKU is a lifelong diet low in phenylalanine.
"It was completely overwhelming," said Doetsch. "We just didn't know, how are we going to feed her? What are we going to feed her? And then when you start looking at the cost, it's like, oh my gosh how are we going to afford to feed her?"
Morgan can't eat meat, dairy, fish, chocolate or other foods high in phenylalanine. Even green vegetables are limited.
Her parents must weigh everything she eats and keep track of how much phenylalanine it contains.
"For her diet, she is allowed 300 mg of phenylalanine a day," said Doetsch. "Say she was to eat a Ritz cracker, right there is 10 mg of phenylalanine, so we have to subtract that from the 300. So every single day, we subtract until we get to zero for the day for her eating."
Most of Morgan's food has to be special-ordered, and it's incredibly expensive. A box of noodles costs $13, a container of imitation egg mix is $60, a loaf of bread is $19.
Morgan must drink three pouches of a special nutritional formula each day. Each pouch costs $8.
"Sadly in Michigan, Michigan is one of the only states that does not cover medical food," said Doetsch. "We've been lobbying trying to get bills passed."
Morgan doesn't let PKU stop her. She loves animals, playing soccer and tennis and reading.
She's learned to deal with her special diet.
"People at my school and my class, people get it right away, they just get that I can't have stuff like that," said Morgan Doetsch. "I normally pack something that I can have kind of close to what they're having, and I just eat that."
But Morgan has a message for researchers.
"Try and search how to find a cure so people don't have to have it."
Morgan's family has found support online from other families dealing with PKU. They follow the research on PKU, but know more money is needed to make real progress.
"We were joking maybe Brad and Angelina will adopt a kid with PKU one of these days," said Erin Doetsch. "Something, because either that or we're just not going to get that recognition and that funding that we so desperately need."
Morgan is currently working to raise money so she can attend the PKU conference in Utah this summer. To donate, click here.
To find out more about the National PKU Alliance, click here.
To learn more about Rare Disease Day, click here.