Ichthyosis vulgaris is inherited as:
1). Ichthyosis is characterized by roughness, dryness and scaling of the skin.
2). It may be subdivided into three subtypes on genetic and clinical grounds viz. ichthyosis vulgaris (autosomal dominant), a more severe form ichthyosis nigricans (X-linked recessive) and the most severe form Harlequin fetus (autosomal recessive). The essential defect in ichthyosis is one of keratinization in which the horny layer is not normally shed.
3). As a result it becomes thicker and drier than normal. Ichthyosis vulgaris begins at the ages of 1-4 years and gets worse during the next few years.
4). In its mildest form (xeroderma) there is only drying and slight scaling of skin.
5). There may be hyperkeratosis at the mouths of hair follicles (ichthyosis follicularis) at the extensor surfaces of limbs and buttocks producing a goose skin appearance.
6). In severe cases there is "heaping up" of grayish brown scales.