Harlequin ichthyosis is a severe and rare genetic disorder affecting the skin. Infants with this condition are born with thick, scale-like skin plates all over their bodies.

Harlequin ichthyosis is the most severe form of congenital ichthyosis, a group of skin disorders that cause persistently thick, rough, dry, and fish-scale-like skin all over the body. This severe and life threatening condition can affect an infant’s breathing, eating, and movement.

This article discusses harlequin ichthyosis, its signs and symptoms, causes, and treatment.

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

Harlequin ichthyosis, also called harlequin baby syndrome, is a rare genetic disorder that affects the skin. Other names for the condition include:

  • ichthyosis fetalis
  • autosomal recessive congenital ichthyosis 4B
  • Ichthyosis congenita

It is an inherited autosomal recessive disorder that affects 1 in 500,000 newborns. About seven children with harlequin ichthyosis are born in the United States yearly. The condition affects males and females equally.

Harlequin ichthyosis is a severe type of ichthyosis. Other types of ichthyosis may have symptoms similar to harlequin ichthyosis.

For example, lamellar ichthyosis is a rare skin condition characterized by dark, plate-like scales separated by deep fissures.

Other types of ichthyosis include:

The symptoms of harlequin ichthyosis may change over time. This condition makes it difficult to distinguish the differences in skin color that would otherwise be visible.

It also varies between newborns, older children, and adults.

Newborns

Harlequin babies are born covered with tight, thick plates of skin. Deep red fissures or cracks split the thickened plates in a diamond-shaped pattern resembling fish scales or alligator-like horned skin.

The tight skin pulls the eyelids (ectropion) and lips (eclabium) open and turns them inside out, revealing their inner red lining. Their eyes and nose may not fully develop, while ears may appear missing or irregular.

The hands and feet may be red, small, and swollen, with the fingers and toes contracted in a curled position. The tight skin also restricts the movements of the arms and legs and limits joint mobility.

The tight skin on the chest and abdomen can restrict breathing. The constricted and swollen mouth can make sucking and swallowing difficult. Many babies with harlequin ichthyosis require tube feeding.

Possible complications

The hardened skin and disrupted skin barrier can also cause other serious issues and complications:

The baby may also develop hearing abnormalities, decreased joint mobility, and respiratory insufficiency. Some may also have multiple digits — polydactyly.

It is common for newborns with this condition to be born prematurely.

Older children

Children who survive the newborn period develop a less severe condition. They continue to present delays in developmental milestones, including motor and social skills. However, they generally match with their peers in terms of mental development.

Children with harlequin ichthyosis will have dry reddened skin covered by large, thin scales throughout their lives. They may also have:

  • poor hair growth
  • unusual facial features
  • scarring alopecia
  • short stature
  • contracture of digits
  • heat and cold intolerance
  • reduced hearing
  • thick fingernails

Harlequin ichthyosis occurs because of the mutation of the ABCA12 gene. This gene gives the body instructions to make proteins in transporting fats to the skin’s epidermis and is also crucial for standard skin development.

The condition is an autosomal recessive disorder when a person inherits an abnormal gene from both parents. If a person receives only one abnormal gene from a parent, they become a carrier of the condition.

There is only a 25% likelihood of both parents passing the abnormal gene to their child, while there is a 50% chance of having a child carrying the abnormal gene. Meanwhile, a child also has a 25% risk of being born without any abnormal gene.

Doctors diagnose harlequin ichthyosis based on the infant’s appearance upon birth. Genetic testing can also confirm the diagnosis by looking for a mutation in the ABCA12 gene.

Specialists may also look at a skin sample under a microscope to see if there are skin changes characteristic of harlequin ichthyosis.

Prenatal testing may also be possible. A doctor may take a skin, blood, or amniotic fluid sample to test the fetal DNA for genetic mutations.

An ultrasound or congenital anomaly scan typically performed during the second trimester onwards may also detect the facial abnormalities commonly seen in newborns with the condition.

A 2018 case reported a diagnosis of the condition during a third-trimester ultrasound checkup.

Read more about pregnancy trimesters.

There is no cure for harlequin ichthyosis. Doctors focus their treatment on protecting the skin and preventing infections and other complications.

Harlequin babies require neonatal intensive care unit (NICU) care. They may need tube feeding to support nutrition and prevent dehydration.

Nurses will place and monitor the infant in a humidified incubator. They will keep track of their heart rate, temperature, respiratory rate, and electrolyte levels.

Health practitioners may frequently apply eye lubricants to protect the eyes. They may also give powerful pain relievers such as opioids to help manage the pain caused by the deep cracks.

Doctors may give retinoids to children with severe cases due to their known toxicity and side effects.

Once the hard scales peel, doctors may give antibiotics to prevent infections.

Management

Harlequin ichthyosis requires an intensive skin care regimen to keep skin moisturized and to prevent cracking and fissuring that may lead to infection.

A person generally applies to soften emollients and moisturizers after a bath while the skin is still moist. These include products containing:

A person may receive oral retinoids to heal skin fissures and plate-like scales. Products that contain keratolytics can help reduce the thickness of the skin and help them peel off.

Sometimes, a doctor may remove bands of tissue known as debridement. This procedure involves removing bands of tissues, which releases constriction of affected areas of the body.

Some may need physical or occupational therapy to help with the restricted joint movement. Counseling may help individuals manage any psychological challenges that come with the condition.

Read on for different types of therapy.

In the past, affected babies did not live for more than a few days. Medical advances now offer a better chance for infants born with the condition. Some have reached their teenage years while others lived into early adulthood.

While the survival rate of harlequin ichthyosis is rising, the mortality rate is still high, at nearly 50% worldwide.

How can a parent know if they are a carrier?

Genetic screening and counseling can determine if one or both couples carry the mutation in the ABCA12 gene. This screening is especially important if one or both has a history of the condition or a previous pregnancy is positive for harlequin ichthyosis.

Parents of children with the condition may find support or more information about the condition from communities like the Foundation for Ichthyosis and Related Skin Types.

Harlequin ichthyosis is a severe, lifelong condition that affects the skin.

Medical advances have significantly improved the outlook of newborns born with the condition. Surviving individuals need continuous monitoring and treatment to keep the skin healthy and protected.