In the United States, ichthyosis affects more than 1 million people of all races and both sexes [source: FIRST]. In its mildest form -- xeroderma -- ichthyosis is simply dry skin that can easily be treated by upping your daily dose of water and applying over-the-counter lotions. But those who inherit more serious forms of the disorder are certain to experience more severe symptoms.
If at least one parent has ichthyosis, there's a 50-50 chance this dominant trait will be passed on to the next generation [source: Skin Sight]. There's good news for those with ichthyosis who once worried about passing on their malady through close contact: It simply isn't contagious. But, you can still acquire it as a side effect of diseases such as AIDS or lymphoma [source: Hershey Medical Center College of Medicine]. However, this happens so rarely that the worldwide prevalence of acquired ichthyosis remains unknown [source: Schwartz].
Most people with inherited ichthyosis are diagnosed with ichthyosis vulgaris [source: Mayo Clinic]. Sometimes this skin condition can be seen at birth, but often it becomes apparent during the toddler or preschool years. What signs should you look for? As the skin fails to shed, it accumulates to form thick, dry scales that are white, gray or dark brown in color. It can also cause deep cracks on the soles or palms that can make it painful to do even the most ordinary activities [source: Mayo Clinic].
Other, less common forms of ichthyosis include lamellar ichthyosis, as discussed on the previous page, and X-linked ichthyosis, which affects only males and causes brown scales on the back, arms and knees [source: Mayo Clinic].
Fortunately, harlequin ichthyosis -- the most severe variation in this family of skin disorders -- is very rare, occurring in only one of every 300,000 births [source: Dolunay]. But it's almost always fatal. Almost. In the mid-1980s, when a San Diego, Calif., mother gave birth to a baby with harlequin ichthyosis, no one expected him to live. The infant, Ryan Gonzalez, had eyelids that were turned inside out; his nose, mouth, ears, fingers and toes were disfigured; and the plates of armor-like skin covering his entire body were separated by deep, wide cracks. This meant his skin, although abnormally thick in places, wasn't a protective barrier against dehydration or infection [source: 10News]. For Gonzalez -- and others with ichthyosis -- the first challenge to living with the condition is to keep the skin moist. What relatively common prescription cream helped him survive? We'll tell you on the next page.