Ichthyosis (also named fish scale disease)[1] is a family of geneticskin disorders characterized by dry, thickened, scaly skin.[2] The more than 20 types of ichthyosis range in severity of symptoms, outward appearance, underlying genetic cause and mode of inheritance (e.g., dominant, recessive, autosomal or X-linked).[3] Ichthyosis comes from Greekἰχθύς (ichthys) 'fish', since dry, scaly skin is the defining feature of all forms of ichthyosis.[4]
The severity of symptoms can vary enormously, from the mildest, most common, types such as ichthyosis vulgaris, which may be mistaken for normal dry skin, up to life-threatening conditions such as harlequin-type ichthyosis. Ichthyosis vulgaris accounts for more than 95% of cases.[5]