Mercedes McDonald and her mom Dawn loved to do Zumba together, but those days dancing together ended when Dawn McDonald was diagnosed with a rare, debilitating condition called Moyamoya disease.

Even though Mercedes can’t share Zumba with her mom like she used to, the 17-year-old Weare senior at John Stark Regional High School decided to incorporate Zumba fitness into a senior project that will raise awareness of Moyamoya and other rare diseases.

Mercedes will hold a Zumbathon on Friday, March 22, from 6:30 to 8 p.m., at Center Woods Elementary School in Weare. Admission is $7, and proceeds from the event will go to NORD, the National Organization for Rare Diseases, an organization raising money and awareness of conditions too rare to have their own charities.

Several area Zumba instructors will participate, including Jenn Abbott, Gina Gluva, Maureen Menard and Robin Morrell. There will also be raffle prizes, and participants will be able to make handprints to send to the “Handprints Across America” campaign, part of NORD, to raise awareness of rare diseases like Moyamoya.

Dawn was 36 in 2011 when she was diagnosed with Moyamoya. The word is Japanese for “puffs of smoke” and describes how areas of the brain appear on scans of people with the disease. Fragile blood vessels that can burst form around blocked arteries in the brain, looking like smoke in the brain.

The disease strikes people in heir 30s but also may appear in children. It causes strokes, headaches and progressively impares cognition and learning.

In those dark areas, the brain is not receiving enough blood flow. So treatment usually involves surgery on the brain to restore circulation. But there are lingering effects.

“My mom has trouble walking and she also had a stroke,” said Mercedes.

Further operations are also likely as the disease may cause further circulation problems in the brain.

Dawn received treatment first at Dartmouth-Hitcock medical Center in Hanover, then later in Boston. Mercedes did research on the disease. It turns out there is only one hospital in the entire country that has a dedicated department to treat Moyamoya; Stanford University Hospital in California. According to their website, women are nearly three times more likely to get the disease than men.

Zumba is no longer something the McDonalds can share.

“My mom has trouble walking and her speech is slurred,” said Mercedes.

The specter of the disease even haunts her as Moyamoya is thought to be hereditary, though neither she or her sister, Sierra, show signs.

Presently there is no cure for Moyamoya disease. It could end her mother’s life. But Mercedes would rather not linger on that. She hopes that her efforts will help improve the quality of her mom’s life going forward.