Last spring, Zack and Sandi Harrison took their young daughters on a vacation to Mexico.

Last spring, Zack and Sandi Harrison took their young daughters on a vacation to Mexico.

Sydney, 4, and Madison, 2, "are beautiful, wonderful, sometimes wild and crazy," said Mr. Harrison.

Throughout their trip, Sydney complained of having tired legs and demanded her parents carry her.

"We just thought it was a behavioral issue," Mr. Harrison said.

When Sydney's complaints continued and she even reduced her participation in the gymnastics classes she loved, her parents became concerned.

A number of tests revealed nothing unusual, but a biopsy of a portion of Sydney's thigh muscle finally provided the answer. Sydney was diagnosed with juvenile myositis, the collective name for a group of rare, life-threatening and incurable autoimmune diseases.

The Harrisons told their daughter's story at the Oct. 8 meeting of the Tri-Village Lions, of which Mr. Harrison is a member. The Harrisons live in Hilliard.

Juvenile myositis "causes a child's own immune system to attack healthy tissues and cells," Harrison said. "This can cause pain, organ failure and even lead to death."

Nearly every system of the body can be affected, including the heart, lungs, skin and muscles, he said.

Videos the Harrisons took of their daughter revealed the difficulties Sydney was facing.

In one, Madison bounds up the staircase after the family returns home from church. Sydney slowly follows, struggling to place one foot after the other as she makes her way up the stairs, clinging to the railing for support.

At times, Sydney would fall to the ground as her legs gave way, Mr. Harrison said.

Unlike most cases of juvenile myositis, blood tests did not uncover Sydney's condition, Mrs. Harrison said. She also did not have the rashes and skin nodules that occur in some forms of the disease.

"That's what made it so difficult" to pinpoint exactly what was wrong, she said.

Sydney finally was diagnosed July 30, the week before her 4th birthday, and immediately began receiving steroid treatments. She also undergoes weekly IV treatments at Nationwide Children's Hospital.

The IV treatments are designed to keep her immune system suppressed while she is weaned off the steroids, Mr. Harrison said. The treatments at Children's Hospital are expected to continue for several more months.

Fortunately, Sydney is responding to the treatments and is again running, playing and climbing stairs, he said.

"She is in a recovery stage" that will hopefully lead to remission, Mrs. Harrison said.

"We won't know she's in remission until she's tapered off the medicine," she said. "We're trying to get it in remission and keep it in remission. It might be in remission for a long time, then show up again years later."

Something as simple as a case of the flu could cause Sydney's immune system to kick into gear and begin attacking her body again, Mr. Harrison said.

The Harrisons created a fundraiser on the Crowdrise site, with all the money collected to be donated to Cure JM, an organization conducting research to find a cure for the disease.

The fundraiser is being coordinated by Lions Club members Doug and Lora Montgomery, who are asking Lions members and the community at large to donate.

Doug Montgomery and Mr. Harrison are among five Lions Club members who work at Simpson Strong-Tie.

Donations may be made at crowdrise.com/teamsydneyforcurejm.

The goal is to raise $5,000 by June 30, 2016, which is the end of the Lions' year, Mr. Harrison said.

Only two to four children out of a million are diagnosed with juvenile myositis annually, he said. The disease affects about 17,000 youngsters in the U.S.

"The trouble is since JM is so rare, there is no financial interest for the pharmaceutical companies to invest millions of dollars to do the research to find a cure," Mr. Harrison said.

Cure JM operates research centers at Chicago Children's Memorial Research Center and George Washington University in Washington, D.C.

"The good news is that any time there is something that throws it into remission, it gives hope to researchers that there is a cure," Mr. Harrison said. "A cure is in reach because they have found a way to get it into remission."

The Lions Club will "serialize" the story of the Harrisons' journey, including information about juvenile myositis and pictures of Sydney. An installment will be posted each Tuesday -- the day Sydney visits Children's Hospital -- to the Lions' Facebook page.

For more information about juvenile myositis and Cure JM, visit curejm.org.