- Rare Disease Day is held on the last day of February each year
- CNN asked readers to share their stories about living with a rare disease
- Families shared stories of perseverance and hope, despite illness
Being diagnosed with a chronic disease -- any disease -- is hard. But imagine first spending months or years going from doctor to doctor, trying to figure out what's wrong. Then, in the end, being diagnosed with a disease few people have ever heard of.
Now think about all that happening when you're just a kid.
Nearly 30 million people in the United States have a rare disease. What qualifies something as a rare? It's a specific disease or disorder that affects fewer than 200,000 Americans, according to the National Institutes of Health's Office of Rare Diseases Research. Scientists have identified more than 6,800 of these diseases worldwide.
In honor of Rare Disease Day, CNN asked readers to submit their stories. We were inspired by these children living with rare diseases. They endure stares, disbelief and debilitating symptoms as they find joy in life's simple pleasures. Here are a few of their stories:
The fact that Sam Brinneman, 16, is alive and well is inspiring all on its own, says his mom, Chris. The Brinnemans knew something was wrong within days of Sam's birth -- he had a weak cry, wasn't nursing well and was "floppy," Chris says. It took three years for doctors to diagnose Sam with mitochondrial myopathy.
Since then, Sam has exceeded everyone's expectations. He's currently a sophomore at a rigorous college-prep high school in Fort Wayne, Indiana. He participates on the school's speech team and in architecture club. Last year he was the state's Goodwill Ambassador for the Muscular Dystrophy Association.
"He was so deathly ill at times as an infant and toddler, that he constantly amazes me with his abilities," Chris said. "The thing that makes me most proud is the fact that he teaches acceptance wherever he goes. Because he is so open about his disease and so willing to share, he has rarely -- next to never -- been teased by his peers."
Sam struggles on a daily basis to get enough calories for optimal nutrition. He wears a breathing machine to bed to treat his sleep apnea. His parents are diligent about keeping him away from sick people, as his immune system is weak.
Yet Sam never uses his disease as an excuse, his mom says. "He has spoken with groups of all sizes, spreading the message about (mitochondrial diseases), including the need for quicker diagnosis, the need for treatment and the hope for a cure."
Cyclic vomiting syndrome
"I never expected my little girl to have to fight a battle with a foe she couldn't see," Tricia Andersen said. But when her daughter, Ali, was 13 months old, she started throwing up and couldn't stop. For a day and a half, Tricia watched as Ali retched painfully and was admitted to the hospital for dehydration. When she was discharged the vomiting episodes continued -- every three weeks like clockwork.
After a year of doctors' visits, Ali was finally diagnosed with cyclic vomiting syndrome. It took the family another six months and a trip to another state to find a medication combination that would work to ease her symptoms. Even then, she was hospitalized half a dozen times by the time she was 9.