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One of the aspirant catwalk stars on America's Next Top Model has the skin disorder vitiligo. How common is the condition?

Chantelle Young, 19, is one of 14 contestants on the forthcoming series of the modelling talent show presented by Tyra Banks. She is the first in the show's history to suffer from the clearly visible skin condition - vitiligo leaves patches of skin with no pigment.

"I have something that's very profound about the way that I look. A lot of people have a story and a background but mine is painted on my body," she said.

But how common is the condition? "A conservative estimate is 1% of the population, regardless of race," says the Vitiligo Society in the UK. "That figure has been around for the past 25 years.

But the society says that many dermatologists now think a figure of 2% may be closer - with more diagnoses as the condition is more widely publicised. A considerable amount of publicity came from knowledge of Michael Jackson having the condition.

"In some cases the psychological consequences can be quite horrendous," says a spokesman for the Vitiligo Society. "Some people are able to cope with it, others just can't."

Dermatologist Dr Shari Lipner, of New York-Presbyterian Hospital and Weill Cornell Medical Center, agrees with the figure of 1%. Under-reporting of the condition is a factor, she says, because patients are embarrassed to come forward. "It may be more common than we think."

The condition is obviously much more noticeable in darker-skinned people, says Lipner, and, particularly if the depigmentation is on the face or hands, the psychological suffering can be worse.

The condition is not curable but can be treated, says Lipner. Steroid skin creams are one of the most common options. Other treatments include light therapy or use of an excimer laser, a form of ultraviolet laser. Another cream containing calcineurin inhibitors is also used. "You can get some of the pigmentation back in some patients," says Lipner, "but not in all patients." Camouflage cosmetics are often used to cover up the affected patches.

The cause of the condition is not known, says Lipner, although some suspect it is an autoimmune disorder - that the immune system attacks pigmentation cells for an as yet unknown reason.

The depigmentation on Chantelle Young's face is almost entirely symmetrical. Despite the striking effect, this is not unusual, "There are different types, but it commonly is symmetrical," says Lipner.

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