Harlequin Ichthyosis

What is harlequin ichthyosis?

Harlequin ichthyosis is a severe disorder that mainly affects the skin. Infants with this condition are born with very hard, thick skin covering most of their bodies. The skin forms large diamond-shaped plates separated by deep cracks (fissures). These skin abnormalities affect the shape of the eyelids, nose, mouth, and ears, and restrict movement of the arms and legs. Restricted movement of the chest can lead to difficulty breathing and respiratory failure.

The skin normally forms a protective barrier between the body and its surrounding environment. The skin abnormalities associated with harlequin ichthyosis disrupt this barrier, making it more difficult for affected infants to control water loss, regulate their body temperature, and fight infections. Infants with harlequin ichthyosis tend to become dehydrated and develop life-threatening infections during the newborn period.

How common is harlequin ichthyosis?

Harlequin ichthyosis is very rare; its exact incidence is unknown.

What genes are related to harlequin ichthyosis?

Mutations in the ABCA12 gene cause harlequin ichthyosis.

The ABCA12 gene makes a protein that is essential for the normal development of skin cells. Although the protein's exact function is unknown, researchers believe that it probably plays a major role in the transport of lipids (fats) in the outermost layer of skin (the epidermis). Mutations in the ABCA12 gene lead to the production of an abnormally small version of the protein that cannot transport lipids properly. The loss of functional ABCA12 protein disrupts the normal development of the epidermis, preventing the skin from forming an effective barrier and resulting in the hard, thick scales characteristic of harlequin ichthyosis

How do people inherit harlequin ichthyosis?

This condition is likely inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder.

What other names do people use for harlequin ichthyosis?

• Harlequin baby syndrome
• HI
• Ichthyosis Congenita, Harlequin foetus Type