Every woman has experienced a bad hair day at some point. But for some women and men, a mysterious illness is causing them to lose all of their hair.

"Your hair is your femininity. It's an expression of who you are," said Dorianne Fengler. For her, that femininity is only possible with a wig. Fengler suffers from alopecia areata, an autoimmune disease where the body develops almost an allergy to hair. Most patients only lose small patches of hair, but others lose everything, including their eyebrows and eyelashes.

"It was very traumatic and took a long time to come to terms with," Fengler said.

But what causes it?

"That is the million dollar question. We really don't understand exactly what causes it," said Dr. Leonard Sperling, a dermatologist.

» National Alopecia Areata Foundation

» Uniformed Services University of the Health Services

Doctors say genetics, environment and stress may all play a part. It's not contagious, and affects all races and ages.

Six-year-old Claudia Oscar began losing her hair when she was only 2. It's all gone now, but partially grows back sometimes.

"Some of the kids tell me I have a little bit of hair, but I don't care very much," Oscar said.

She owns wigs, but usually they're cast aside.

"I just want to have no hair on," Oscar said.

"I prefer her feeling comfortable about how she looks," said Claudia's mother, Terry Oscar. "She's just like everybody else. The only difference is she doesn't have any hair."

Retired Colonel Ray Monroe lost all of his hair, then it grew back. Now, it's gone again. He says it's been emotionally draining.

"You're always thinking about it now because it's like, OK, some people are glancing at me, what are they thinking? Is it really that obvious?" said Monroe.

He's hoping to save his eyebrows and gets anti-inflammatory injections every eight weeks. The injections, as well as creams and foams, can also be used on patients' scalps. But doctors say there's no guarantee anything will work, and results vary patient to patient.

"Accept it and live with it and if it grows back, I'll be thrilled. If it doesn't, I've come to terms with it," said Fengler.

Dr. Sperling say 90 percent of the time, patients' hair grows back, even without treatment. Whether hair grows back or not, he says, it's crucial patients contact support groups like the National Alopecia Areata Foundation to cope with this mysterious disease.

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