Although HI is inherited in an autosomal recessive fashion, it has been only in recent years that human molecular geneticists discovered the underlying cause of HI. Specifically, these scientists determined that mutations in a gene that is designated ABCA12 are responsible for causing HI.
In normal individuals, the ABCA12 gene encodes a protein, a type of ATP-binding cassette reporter protein, that is necessary for the normal development of skins cells. A function of ATP-binding cassette reporter proteins is to transport various molecules that are needed in the skin across cell membranes. One class of molecules that these proteins transport is lipids (fats), which are essential components of the outer layer of the skin (which is known specifically as the epidermis). Those who are mutant in both of their copies of the ABCA12 gene are unable to synthesize fully functional ABCA12 version of the ATP-binding cassette reporter protein (or may not make this protein at all). Due to this deficiency, lipids are not sufficiently carried from deep within the skin to its outer epidermal layer, which causes these individuals to suffer one or more of the skin problems that were described in the previous section.
This article is only meant to provide some basic information regarding the genetic condition known as harlequin ichthyosis. If you have any further questions regarding this inherited disorder, please contact your doctor or consult a genetic counselor.
