They're the diseases that don't get much, if any, attention, but to the people who have them and their families, they are no less devastating.
Friday, Feb. 28 has been designated Rare Disease Day -- a day designed to raise awareness of the illnesses you don't often hear about.
There are nearly 7,000 so-called "rare diseases." These are conditions that affect less than 200,000 people in the United States.
While each disease may be rare, all of those diseases together affect nearly 30 million Americans.
Actress Patricia Richardson is best known for her starring role on the television show "Home Improvement," but it was her role as a loving daughter that convinced her to join the fight against rare diseases.
"This is about rare diseases, but it's not a rare experience," said Richardson. "My father passed away in 2005 of a rare disease called PSP which stands for progressive supranuclear palsy."
Like so many patients with a rare disease, Laurence Richardson faced years of misdiagnoses.
"When they do diagnose it, it's almost worse because they say, 'Oh, what he has, we don't know what causes it, we don't have a treatment, we don't have a cure, but it's fatal,'" said Richardson.
Richardson found support from the National Organization For Rare Disorders, also known as NORD.
"When you take all 7,000 rare diseases, it's actually quite a large number of people, and the experience can be quite similar," said Tai Spargo, assistant director of communications for NORD. "Rare Disease Day is an opportunity to shed light on that fact and come together to raise awareness."
NORD's slogan is "Alone we are rare, together we are strong."
The organization provides information for patients and families, mentoring for patient organizations, research grants, patient assistance programs and advocates for issues affecting those with rare diseases.
More research is desperately needed. According to NORD, only about 300 of the 7,000 rare diseases currently have an FDA-approved treatment.
Richardson has worked to raise money and awareness for PSP, but she wants to see all rare diseases receive more support for patients and their caregivers.
"The most important thing to do is find someone else, get information, go online, find a support group, get somebody else who is going through what you're going through," said Richardson. "We are not alone. You're not the only one."
To learn more about Rare Disease Day, click here.
To show your support for Rare Disease Day on Facebook, click here.
To visit NORD's website, click here.
It's estimated 80 percent of rare diseases have a genetic cause. Some supporters plan to wear jeans today to show their support. To learn more about the Global Genes project, click here.