The first thing Brian H. noticed was that he could grow a real beard. It had been years since that had been possible, years he spent bedeviled by hair loss on his head, face, arms and legs.

Brian, 34, who asked that his last name be withheld to protect his privacy, suffers from alopecia areata, an autoimmune disease afflicting about 1 percent of men and women, causing hair to fall out, often all over the body. He believes that the “mangy patches” of baldness that have plagued him since his 20s have cost him jobs and relationships.

After trying various treatments, Brian enrolled this year in a study at Columbia University Medical Center testing whether a drug approved for a bone marrow disorder could help people with alopecia. One of the study’s leaders, Angela Christiano, is a dermatology professor and geneticist who herself has alopecia areata.

After successfully testing on mice two drugs from a new class of medicines called JAK inhibitors, which suppress immune system activity by blocking certain enzymes, the researchers began testing one of the drugs, ruxolitinib, on seven women and five men. Some of their findings were published Sunday in the journal Nature Medicine.