"What I tell patients is that sarcoidosis is an inflammatory disease that affects different people in different ways," Moller says. "We don't know what triggers this inflammation, and it can occur in a number of areas in the body."
The symptoms of sarcoidosis -- symptoms such as fever, rash, fatigue and breathing problems -- are also shared by a number of other diseases.
"These are symptoms that are often dismissed by doctors as not important," Durrer says. "And they can be interpreted by family members as somebody who is just complaining. This can really impact quality of life."
The numbers may be further skewed because, in the United States, the disease primarily affects African-Americans, who, past research shows, are less likely than other racial groups to get appropriate medical treatment and care.
And, despite the lack of awareness of the condition, Durrer estimates about one in 2,000 people in the United States is living with a sarcoidosis diagnosis -- although Moller says that it's widely recognized in medical circles that sarcoidosis is underdiagnosed.
"Most people have not heard of sarcoidosis until they are actually diagnosed with it, so it can be very isolating," Durrer says.
Research continues to uncover clues about the origins of the disease. Moller says that the development of sarcoidosis in a given individual is probably contingent on two factors. One is a genetic susceptibility to the condition. The other is a trigger, which may be linked to bacterial infection.
"I think the scientific evidence has been increasing to the point that most physicians who do research in sarcoidosis believe that it is triggered by infectious agents in patients who are genetically susceptible," he notes.
Still, the exact cause continues to elude researchers.
"That's a tough pill for a patient to swallow when you can't tell them what caused their disease," Durrer says.
People with sarcoidosis may also have to wait for an effective cure, although treatments to control the disease are available.
Wilson is on a special regimen of immunosuppressive drugs to control inflammation, as well as "a whole host of painkillers every single day to get through the day."
The medicines are not without their side effects -- not the least of which is a weakened immune system, which makes her susceptible to pneumonia and other infections.
"I have to wear a mask when I travel, and when I am in crowded areas, I wear a mask," she says. "I'm sure I scare people half to death. 'What I have you can't get' is what I say to them. ... Keeping a sense of humor intact is key."
Wilson also says she imagines that Mac may have also used his famous humor to fight his condition with a daily dose of hope. And Moller remains optimistic that Mac's battle with sarcoidosis will also bolster hope in the many who live with the disease.
"One of the reasons that many of us are willing to provide information is that sarcoidosis is not a rare disease," he says. "I think there is a lack of public awareness of this disease, and that's something that perhaps the medical community would benefit from, having awareness raised ... so tragic outcomes like this may be prevented."
For more information about sarcoidosis, visit the Web site of the Foundation for Sarcoidosis Research at www.stopsarcoidosis.org/.