Harlequin ichthyosis is a very rare genetic skin disorder. It is the most severe type of ichthyosis.
Harlequin ichthyosis is caused by a mutation of the ABCA12 gene, and the baby receives one mutation from each parent, who are carriers but do not display any signs of the condition themselves.
Because of this mutation, babies with Harlequin lack a protein that helps the top layer of their skin (the epidermis) form correctly. To try to compensate for this missing protein, the body makes too much skin, and the body can't shed it quickly enough.
Babies affected with Harlequin are born with extremely thick plates of skin - almost like armor - with deep red fissures over their entire bodies. This thick skin pulls tightly, causing deformed facial features. The eyes are pulled so tightly that the lids are flipped inside out and bright red from irritation. Often the nose and ears are barely able to be seen under the plates of skin. And the fingers and toes are contracted and shortened due to the pulling of the thick skin.
Immediate concerns after birth are infection due largely to the deep fissures, dehydration, and breathing, because the skin restricts movement in the chest.
Eventually, the original skin wil peel off, leaving reddened and flaky skin underneath. However, dehydration, temperature changes and infection will always be a concern for children with Harlequin ichthyosis because their epidermis doesn't regulate their own body temperature, hold in moisture or keep out bacteria.
Until recent years, babies born with Harlequin rarely survived past the first few days, but with recent advances in neonatal care, more infants with Harlequin are surviving now, according to the Foundation for Ichthyosis and Related Skin Types (FIRST). The oldest person with Harlequin is in her late 20s.