Ichthyosis (Ichthyosis vulgaris)
Ichthyosis vulgaris (also known as Autosomal dominant ichthyosis) and Ichthyosis simplex is a skin disorder causing dry, scaly skin. It is the most common form of ichthyosis affecting around 1 in 250 people. For this reason it is known as common ichthyosis. It is usually an autosomal dominant inherited disease (often associated with filaggrin), although a rare non-heritable version called acquired ichthyosis exists.
The symptoms of the inherited form of ichthyosis vulgaris are not usually present at birth but generally develop between 3 months and 5 years of age. The symptoms will often improve with age, although they may grow more severe again in old age.
The condition is not life-threatening; the impact on the patient, if it‘s a mild case, is generally restricted to mild itching and the social impact of having skin with an unusual appearance. People afflicted with mild cases have symptoms that include scaly patches on the shins, fine white scales on the forearms and upper arms, and rough palms. People with the mildest cases have no symptoms other than faint, tell-tale "mosaic lines" between the Achilles tendons and the calf muscles.
Ichthyosis vulgaris is one of the most common genetic disorders caused by a single gene. The disorder is believed to be caused by mutations to the gene encoding profilaggrin (a protein which is converted to filaggrin which plays a vital role in the structure of the skin). Around 10% of the population have some detrimental mutations to the profilaggrin gene that is also linked to atopic dermatitis (another skin disorder that is often present with ichthyosis vulgaris). The exact mutation is only known for some cases of ichthyosis vulgaris.