It began last summer with a limp that went from growing pains to a diagnosis of leukemia.

By now, it's grown to a group of 100 volunteers determined to find a bone marrow match for the afflicted 11-year-old Mt. Lebanon girl.

Some day, it could be a nationwide movement to register potential bone marrow donors for people with cancer.

Jefferson Middle School sixth-grader Amy Katz was diagnosed in September with chronic myelogenous leukemia, a rare type for someone her age. The only known cure is a stem cell transplant. She's on a drug regimen that has beaten back, but not vanquished, the disease.

But she has many people pulling for her -- an army, in fact, that stretches across the community.

"We have really found the kindness of strangers," her mother, Lisa Katz, said Friday.

The support group, named Amy's Army, started among Lisa Katz's friends and fellow worshipers at Temple Emanuel of the South Hills.

"We have to do something," volunteer Kate Rosenthal said. "We weren't taking no for an answer."

The group has had two marrow screenings and continues to find potential donors, for Amy or others.

But the process costs money, and the army also handles that. Its next fund-raiser will be a movie night at 6 p.m. Sunday at Star City Cinemas.

Children help, too, organizing everything from lemonade stands to Penny Wars in the Mt. Lebanon schools.

Children get their parents involved, said Steve Hausman, who's on the army steering committee.

"It's brought the community together," he said

Amy was diagnosed after knee soreness that wouldn't go away.

Her older sister Jenny and younger sister Katie were tested as potential marrow donors. A sibling has about a 25 percent chance of being a match, but any other family member has as much chance of being a match as does a stranger.

Katie and Jenny matched each other. Neither matched Amy.

Most cancer patients can't find a match from a stranger through their own efforts and rely on the National Marrow Donor Program. The Katzes started conducting marrow donor drives. The first was in December, for Gift of Life, a registry for people of Jewish descent. The second drive was in February at Temple Emanuel. The third will be May 23 in Squirrel Hill.

The screening process involves a blood test that puts a person on the program registry. Laboratories analyze the person's genetic fingerprint, and doctors use the database to find potential donors.

Even with more than 5 million people on the registry, it's a slim chance that someone will actually be called to be a donor, Lisa Katz said.

Rosenthal hopes that the campaign to find a donor for Amy will spread and increase the number of people on the registry -- and the number of patients who might be helped.

"Someone's match will be found through these donor drives, and, God willing, it'll be Amy," Lisa Katz said.

Vince Guerrieri can be reached at vguerrieri@tribweb.com or (412) 380-5607.