Inside the little-known disease that causes babies to be born with hard scales

It’s one of the rarest — and most devastating — genetic disorders doctors encounter.

Harlequin ichthyosis affects just a handful of newborns each year in the US, but the condition is unmistakable, marked by a thick, armor-like layer of hard scales at birth.

Once considered a death sentence, medical advances have helped some children survive into adulthood. Here’s everything you need to know about the strange and severe disease.

What is harlequin ichthyosis?

It’s the most sever form of ichthyosis, a family of more than 20 skin conditions that interfere with how the body produces and sheds skin cells, according to the Cleveland Clinic.

The bodies of babies born with harlequin ichthyosis are covered with plates of hard, thick skin. These plates crack and split, leaving deep, painful fissures across the body.

The extreme tightness of the skin can force the eyelids and lips to turn inside out and constrict the chest, making it difficult to breathe.

Babies with the condition often appear to have flat noses and misshapen or missing ears — though the ears are usually present but fused to the head by thickened skin. Other symptoms may include hearing problems, limited joint mobility and small, swollen hands and feet.

What causes it?

Harlequin ichthyosis is caused by a rare genetic mutation. A baby has to inherit two copies of the faulty gene — one from each parent — for the condition to develop.

The gene involved, called ABCA12, is responsible for producing a protein essential for healthy skin development, according to DermNet.

This gene helps move fats to the outermost layer of the skin, creating a protective barrier. When the gene doesn’t work properly, this barrier is disrupted, leading to the severe skin problems seen in harlequin ichthyosis.

How rare is it?

Harlequin ichthyosis affects about 1 in every 500,000 births, or roughly seven babies a year in the US, per the National Organization for Rare Diseases.

The condition affects males and females equally, and isn’t more common in any specific racial or ethnic group.

Is it fatal?

In the past, infants with harlequin ichthyosis rarely survived past the newborn period. But today, with advances in medical care, some children are living into their teens and even adulthood.

Still, the condition remains dangerous. The broken skin barrier makes it harder for babies to hold in fluids, regulate body temperature and fight off infections — putting them at serious risk for dehydration, sepsis, respiratory failure and other life-threatening problems.

Can it be treated?

When a baby is born with harlequin ichthyosis, they are immediately taken to the neonatal intensive care unit. There, they stay in a high-humidity incubator to help regulate their body temperature, according to the Cleveland Clinic.

Nurses regularly bathe the infant to soften the thick skin and loosen the hard scales, and apply moisturizers to help make the skin more flexible and prevent dryness.

In severe cases, babies may be given an oral medication called etretinate, which can help break down the thick skin plates and improve symptoms. However, this treatment is used cautiously because it can cause serious side effects with long-term use.

If a baby survives the critical newborn stage, they will gradually shed the thick plates, but their skin will remain red and scaly.

Lifelong medical care is necessary to manage the condition.