Looking at Texas teenager Desiree Simmons, you might easily think she was born white. You'd be wrong.
"I know that I'm a black girl and that's what I am, even though it appears that I'm something else," Desiree said.
A medical mystery doctors still don't fully understand made her skin color different from that of her brother and her parents. When people see them together, many assume the 14-year-old was adopted.
But Desiree was born with the same skin tone as the rest of her family.
When Carolyn Simmons first noticed a white spot on her 5-year-old daughter's finger, she thought Desiree had burned herself in the kitchen.
It wasn't until the spot grew that she started asking around and a friend told her it might be vitiligo. Carolyn Simmons said the name rang a bell: "I was like, what's that V-word?"
What started as a tiny dot on Desiree's' finger also appeared on her knees and feet and continued to spread. Her mother said that within six months the disease had advanced to every part of the little girl's body.
The mysterious and increasingly worrisome ailment was finally diagnosed. Desiree had vitiligo, a skin condition affecting more than 1 million Americans, according to the National Institutes of Health. The good news is that the disease is not fatal. The bad news is there's no cure and the cause remains a mystery.
With vitiligo, pigment cells that provide skin color are suddenly attacked by the body's immune system and destroyed one cell at a time. The disease affects people of both sexes and all races equally, but is much more noticeable in those with darker complexions.
Researchers have identified a gene common in vitiligo patients, but for the disease to blossom it needs a trigger, and that could be almost anything.
"We have patients who say, I got mono and then a month later I had white spots," said Dr. Nanette Silverberg, a vitiligo specialist at New York's Beth Israel Medical Center. "I've had a patient say, 'I got divorced, within a few weeks I had white spots on my skin.' There is no one universal factor."
Doctors had no explanation for why Desiree suddenly developed vitiligo.
Vitiligo may not be life threatening, but it can be psychologically devastating. Patches of depigmented skin appear seemingly at random, altering a person's appearance and sometimes threatening to upend one's identity. It's common to try and hide it with makeup, but the Simmons family opted against that solution.
"We wanted Desiree to feel good about herself," Carolyn Simmons said. "You know, this is who you are." She said the family chose to work on Desiree's self-esteem and build her confidence, focusing on the girl and not the disease.
After three years, vitiligo covered 60 percent of her body. Doctors couldn't say whether or where the disease would continue to spread.
Vitiligo progresses differently with each patient, according to Silverberg.
"There are no blood tests, there are no biopsy tests," she said. "There are no X-rays or scans you can do, no MRIs, ultrasounds. There's just nothing that will predict the course of illness."
Vitiligo can stop as suddenly as it begins and can come back at any time.