Harlequin Ichthyosis - What is it?

Harlequin Ichthyosis

What is it? ....

Harlequin Ichthyosis (HI) is a rare autosomal recessive genetic disorder of skin and the most severe form of congenital ichthyosis— characterized by a thickening of 'Keratin Layer' of fatal human skin. The skin forms large, diamond-shaped plates that are separated by deep cracks (fissures). These skin abnormalities affect the shape of the eyelids, nose, mouth and ears as well as limit the movements of the arms and legs. Restricted movement of the chest can lead to breathing difficulties and respiratory failure.

The Name came from....

The term 'Harlequin' derives from the newborn's facial expression and the triangular & diamond-shaped pattern (resembling the costume of Arlecchino) of 'hyperkeratosis' . The newborn's mouth is pulled wide open, mimicking a 'crown's smile'.

Babies with harlequin ichthyosis are born prematurely, covered with thick, hard, armor-like plates of cornified skin separated by deep fissures. The thick skin plates can pull at and distort the infant's facial features. The tightness of the skin pulls around the eyes and mouth, forcing the eyelids and lips to turn inside out, revealing the red inner skin. The chest and abdomen of the infant may be severely restricted by the tightness of the skin, making eating and breathing difficult. The hands and feet may be small, swollen and partially flexed. The ears may appear to be misshapen or missing but are really fused to the head by the thick skin.

In harlequin infants premature birth is typical, leaving the infants at risk for additional complications from early delivery. These infants are also at high risk for difficulty of breathing, infection, low body temperature and dehydration. Constriction and swelling of the mouth may interfere with the suck response and infants may need tube feeding. Medical monitoring is difficult because of the abnormal skin; electrodes cannot be placed effectively and blood vessels cannot be seen under the skin. Placing lines in the artery and vein of the umbical cord can aid in monitoring the infant and delivering fluids and nutrition. These infants may have problems maintaining normal levels of electrolytes especially sodium in their blood. They are particularly prone to develop hypernatremia (high sodium levels in blood). The baby's corneas need to be lubricated and protected if the eyelids are forced open by the tightness of the skin. A high humidity environment is a heated incubator is necessary to help maintain body temperature and to prevent the skin from cracking.

The thick plate like skin will gradually split and peel off. Antibiotic treatment may necessary to prevent infection at this point of time. Administration of retinoid such as oral etretinate (1mg/kg body wetght) may accelerate sheding of the thick scales. But a hurdle also exists here— it takes a week or two for etretinate to work loosening the scales.  Because most of the fatalities from this condition occur in the first few days of life, many of the successes attributed to etretinate use in the medical literature may be equally due to the high quality of care in the immediate new-born period and to a less severely affected new-born.  Unfortunately, because of the severity of their condition, some new-borns with harlequin ichthyosis will not survive, even with the best of care.