What is harlequin ichthyosis?

Skin Problems Image Gallery The hard, diamond-shaped scales that harlequin ichthyosis produces are reminiscent of the harlequin theater character. See more pictures of skin problems.

The skin is our largest organ, and probably the most underappreciated. It protects us against viruses, bacteria, pollution, the elements, and, let's not forget, it holds our insides on the inside and keeps them from mixing with the outside.

On top of all that, it's because of our skin that we're able enjoy a full range of motion. Tough yet springy, normal skin springs back into shape when pressed, twisted or pulled. It has complex mechanisms that allow for oil to coat the skin, providing further protection. It helps us maintain a consistent body temperature and serves as our detection system for identifying hot and cold. And, like the inside of a military-grade vehicle, it can be hosed off and come out clean and looking as good as new.

That is, when the skin works properly. There are many diseases that can keep the skin from doing its job, some more serious than others. One genetic condition severely impairs all of the skin's functions that we normally take for granted. It's called harlequin ichthyosis.

This disorder, also called ichthyosis fetalis, prevents the skin from forming a protective layer. Instead, it produces hard, scalelike, diamond-shaped plates separated by deep ridges. The deep ridges between the distinctive plates severely compromise the body's first line of defense against toxins, bacteria and pollution, and the hard plates disrupt the skin's usual system of constantly replacing and sloughing off dead skin cells.

Harlequin ichthyosis not only creates mayhem within the body's immune system, it also drastically affects the development and shape of facial features. Babies born with harlequin ichthyosis have mouths that are pulled open, almost resembling an exaggerated, clownlike smile, hence the name "harlequin." The infant's ears may be practically absent, and he or she may also have eyelids that look like they're turned out. But these physical changes aren't just an aesthetic concern -- the mouth's unusual structure makes it difficult for newborns to eat, for example, and the eyelids can't protect the baby's eyes.