Ichthyosis is a family of genetic skin disorders characterized by dry, scaling skin that may be thickened or very thin. Harlequin ichthyosis is the most severe form of congenital ichthyosis. It is also known as "Harlequin baby," Harlequin ichthyosis, ichthyosis congenita, Ichthyosis fetalis, keratosis diffusa fetalis, "Harlequin fetus," and "Ichthyosis congenita gravior". Harlequin ichthyosis is a recessively inherited genetic disorder.