Harlequin-type ichthyosis

From Biology-Online Dictionary | Biology-Online Dictionary



A form of ichthyosis that is often associated with a defective ABCA12 gene, and characterized by the development of thickened skin in the form of diamond-shaped plates over nearly the entire body of the newborn


Ichthyosis is a skin disorder characterized by having a dry, thick, scaly skin. Its name is derived from the Greek ichthys meaning fish. The skin is compared to the scaly outer covering of the fish. The scaly appearance of the skin is due to excessive skin keratinization or cornification.

Harlequin-type ichthyosis is a form of ichthyosis that is associated with defective ABCA12 gene. The gene codes for ATP-binding cassette transporter 12, which is a protein member of the ATP-binding cassette family involved in transporting molecules across cell membranes. The gene is active in certain cells, such as some skin cell types where it is essential in skin development. For instance, it transports epidermoside from the keratinocytes of the stratum corneum.1 Mutations involving this gene could lead to harlequin-type ichthyosis or to lamellar ichthyosis type 2 (i.e. amino acid substitution mutation in the ABCA12 protein). Mutation in ABCA12 gene leads to the lack of ABCA12 protein production or to a dysfunctional ABCA12 protein. As a result, both prenatal and postnatal development of epidermis is affected. The infant, thus, develop thick and hard skin over (nearly) the entire body at birth, characteristic of harlequin-type ichthyosis.


  • Harlequin ichthyosis
  • hyosis fetalis
  • keratosis diffusa fetalis
  • harlequin fetus
  • ichthyosis congenita gravior

See also:

1 Ishibashi, Y., Kohyama-Koganeya, A., & Hirabayashi, Y. (2013). "New insights on glucosylated lipids: Metabolism and functions". Biochim. Biophys. Acta. 1831(9): 1475–1485.