BETHESDA, Md. (WUSA9) -- Half of all rare diseases affect children and genetic research is clearing the way for better diagnosis and treatment options. But, rare diseases may be more common than once thought.

Kayla Mills is seven-years-old, she lives in Hollywood, Florida but she is here at NIH's Clinical Center. She is getting aggressive treatment for her condition.

Kayla's mom, Amy says, "Her condition is very rare, Autoimmune polyglandular syndrome type-1, the statistics are one in two million in the United States. We noticed Kayla was really sick about three-months-old. We got a diagnosis at two-and-a-half after we almost lost her."

Kayla's lungs and glands inflame and as a result, her body is attacking itself. Kayla is getting treatment aimed to suppress her T-Cells and B-Cells, suppressing the immune system.

While Kayla is getting treated in Maryland, her family is staying at The Children's Inn at NIH.

"The inflammation, the chronic pneumonias cause more permanent damage and again the end prognosis is end-stage lung disease. And that would mean losing part of her lungs, both lungs, so that's not an option," adds Mills.

Dr. John I. Gallin, Director of NIH Clinical Center says so-called "rare diseases" are not so rare after all.

Dr. Gallin says, "It's estimated up to 30 million Americans have a rare disease, maybe one in 10 Americans have a rare disease."

Advances in genetics help to identify more of these illnesses. This is the focus of Rare Disease Day at NIH, aimed to spread the word about these conditions.

"Every time we understand the genetic basis of a common disease, we identify new rare diseases. So for example, breast cancer is no longer one problem, it's a whole family of genes that become mutated that cause breast cancer so it's a group of rare diseases, and this is true for almost every disease," adds Dr. Gallin.

Kayla is part of a research study and lately she has seen a few ups and downs. But her family is optimistic that she is in good hands.

Mills says, "It gives me the most piece of mind because this is the most comprehensive study on APS1 in the United States of America. She is receiving amazing care from our research team here and they all coordinate with her doctors at home which is phenomenal as well."

Dr. Gallin says, "What we need to do is one educate people so that they can become familiar with this, we need to educate the funders whether they are in the Congress or the philanthropy. We need individuals to donate money to advocacy groups for the special diseases that people care about and then money can help to nurture the science."

"And once we nurture the science we can go from identifying at a very specific molecular level to designing new drugs to attack the problem," adds Dr. Gallin.