Harlequin-type ichthyosis (also harlequin ichthyosis, ichthyosis congenita, Ichthyosis fetalis, keratosis diffusa fetalis, and Harlequin fetus[1]:562), a skin disease, is the most severe form of congenital ichthyosis, characterized by a thickening of the keratin layer in fetal human skin. In sufferers of the disease, the skin contains massive, diamond-shaped scales, and tends to have a reddish color. In addition, the eyes, ears, mouth, and other appendages may be abnormally contracted. The scaly keratin greatly limits the child's movement. Because the skin is cracked where normal skin would fold, it is easily pregnable by bacteria and other contaminants, resulting in serious risk of fatal infection.