Based on those words alone, it's easy to think a rare disease automatically translates to a rare experience: battling a condition that is not well-understood, under-researched, and likely without a cure.
"You feel really alone. You feel lonely, you feel powerless, and you feel like your experience is rare," actress Patricia Richardson, best known for her roles on "Home Improvement" and "Strong Medicine," explains to HuffPost. "But it's not. There's 30 million Americans with rare diseases. It's not a rare experience. What you're going through is not rare."
Keeping this in mind can help provide the support and strength that is needed to fight against a condition that most people have never heard of, she says.
Friday, Feb. 28 is Rare Disease Day, which is an internationally recognized day meant to bring awareness to this public health challenge. According to the Food and Drug Administration, a rare disease is officially classified as such when it affects fewer than 200,000 Americans at any one time. (In Europe, it's defined as affecting fewer than one in 2,000 people.)
According to the National Organization for Rare Disorders, there are 6,000 to 7,000 rare diseases. Some rare diseases are more well-known than others, and some cancers are even considered rare diseases. NUT midline carcinoma, for instance, is a rare kind of cancer that develops in the "midline" of the body (meaning, the chest, upper airways, mouth, sinuses and trachea); only about 30 cases of this cancer are diagnosed each year. Neuroblastoma is another type of rare cancer that mainly affects infants and young children, and develops in the tissues forming the sympathetic nervous system; about 710 children are expected to be diagnosed this year with this kind of cancer, according to the American Association for Cancer Research.
Richardson, whose father passed away from a rare brain disorder called progressive supranuclear palsy (PSP) nearly a decade ago, explained that the whole process of a medical diagnosis is exponentially harder when it involves a rare disease. Her own father, for instance, was incorrectly diagnosed with Parkinson's disease before finally being correctly diagnosed with PSP.
PSP "looks a lot like Parkinson's -- with Parkinson's, they fall sideways, but with PSP, they fall backwards. With Parkinson's, they can't look sideways, and with PSP they can't look up and down," she explains. "That's why neurologists miss it."
Richardson says that the most important thing a person can do when faced with a rare disease, whether firsthand, or as a caregiver, is to find a support group. Groups such as the National Organization for Rare Disorders -- established in 1983, the same year the Orphan Drug Act was passed to incentivize the development of drugs for rare diseases -- can help to connect people with others going through similar experiences, she said, not only for practical matters (like advice on helping your loved one walk or use the restroom) and information about the condition (such as realizing common symptoms), but also for emotional support.
"The most important thing, and I know this because we didn't have it, is to get support," Richardson says. "It's to connect with other people."
Watch Richardson's conversation with HuffPost Live below: