Two doctors at Yale University may have found a treatment for hair loss.

Published on June 18 in the Journal of Investigative Dermatology by Dr. Brett A. King, assistant professor of dermatology at Yale’s School of Medicine, and New Haven-based dermatologist Dr. Brittany G. Craiglow, the study lookedata 25-year-old unnamed patient with a severe case of alopecia, the autoimmune disorder that causes individuals to lose some or all of their hair. According to the National Organization for Rare Diseases, 2.5 million people in the United States suffer from the disease, which has no known treatment at present.

The patient was originally referred to the university’s dermatology department for his five-year-long battle with plaque psoriasis, or itchy, raised red patches on the skin, Dr. King tells The Daily Beast.

“When I walked into the room to meet him, I immediately recognized that he did not have eyebrows or eyelashes, and soon thereafter realized that he had Alopecia Universalis,” he said of his first encounter with the patient nearly 10 months ago. King remembered that a researcher from Columbia University had given mice suffering from alopecia doses of Tofacitinib, an FDA-approved medicine for rheumatoid arthritis. The mice were grafted with 100% hairless human skin and then administered the drug. Five of the seven mice saw new hair growth.  Additionally, early clinical trials have indicated that the drug might also help treat psoriasis. King decided to use the psoriasis diagnosis to argue to the insurance company that the patient should be allowed to try Tofacitinib. “That kind of supported multiple appeals to his insurance company to let me try to treat both his diseases with one medicine.”

The patient, who, according to the study “had no eyebrows, eyelashes, or facial hair and no hair on his arms, legs, torso, or in the axillae or groin,” was administered 10 mg daily of Tofacitinib Citrate (more commonly referred to by its brand name, XELJANZ) for the first two months; the dosage was then increased to 15 mg daily for the following three months. By the end of eight months, the drug had successfully sparked full hair growth for the young man.

The success of Tofacitinib as a treatment for psoriasis, alopecia, and rheumatoid arthritis lies in the similar genetic make-up of the three diseases, King says. “There are commonalities amongst these different conditions, genetic susceptibilities that are common amongst them.”

At this time, the patient remains on the daily treatment of Tofacitinib. “It may go away again at some point,” King says. “He has psoriasis and as much as we know about that and its treatment, we know that you have to treat and treat and treat. There’s no cure, per se. And so, to the extent that we continue to treat his psoriasis he will be on the medicine, and should we at any point choose to treat [it] with something different, then we will learn how durable the effect is for his alopecia.”

For those hoping this groundbreaking discovery will translate into cures for more common diseases, such as male pattern baldness, King advises caution. “What we know about male pattern hair loss at this time would not indicate that Tofacitinib will treat it. But, a slightly different take on that is that five years ago, if somebody had said [to me], “Do you think that Tofacitinib would treat Alopecia Universalis?’ I would have said, ‘Well, the current science does not support that it would be helpful.’ So, I certainly don’t want to promote the idea that this is going to be the cure or the treatment of male pattern baldness, but I do think that this is such an enormous step forward in the treatment of Alopecia, that to wonder if there aren’t things in common between [one] kind of alopecia and [another] that might permit this medicine to work in both. Why wouldn’t we imagine that?”