Ichthyosis vulgaris (also known as "Autosomal dominant ichthyosis,"[1] and "Ichthyosis simplex"[1]) is a skin disorder causing dry, scaly skin. It is the most common form of ichthyosis,[2]:486 affecting around 1 in 250 people.[3] 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.[4]:560