Harlequin Ichthyosis – Symptoms, Causes, Test, And Treatments

Overview

Harlequin ichthyosis is a rare genetic disorder that affects the skin. It is a severe form of congenital ichthyosis that causes the skin to become thick, rough and dry, which makes the skin appear scale-like all over the body.

The disorder can be life-threatening and affects the infant’s eating, breathing and movement patterns. The disorder is also called as baby syndrome, and the other names include

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

According to the National Organisation for Rare Disorders (NORD), about 1 in 500,000 newborns are affected with this disorder. Additionally, the disorder equally affects both male and female infants.

Harlequin ichthyosis is a severe form of skin disorder, and the other types may have similar symptoms as harlequin ichthyosis. Lamellar ichthyosis is characterised by dark, plate-like scales separated by deep fissures.

Some of the common types of ichthyosis include

• Congenital ichthyosiform erythroderma
• X-linked ichthyosis 
• Ichthyosis vulgaris
• Epidermolytic hyperkeratosis

Causes of Harlequin Ichthyosis

Harlequin ichthyosis occurs due to a mutation of the ABCA12 gene. The primary function of the gene is to give instructions to produce the protein that is required for the normal development of the skin.

The gene also plays an important role in the transportation of fats to the superficial layer of the skin, which creates an effective skin barrier. When the gene mutation occurs, the skin barrier is disrupted, which leads to the disorder.

Harlequin ichthyosis can be inherited in an autosomal recessive pattern. The recessive genetic disorder occurs when the child inherits an abnormal gene from both parents.

If the child inherits the abnormal gene from one parent and inherits the normal gene from another parent, the infant will not show any symptoms. However, the child will become the carrier of the disorder.

The risk of both parents carrying the abnormal gene to pass the disorder to their child is about 25% in each pregnancy. The risk for the child to become a carrier is 50%. However, there is a 25% chance for the child to receive normal genes from both parents.

Symptoms of harlequin ichthyosis

Newborn

Infants born with the disorder are covered with thick plate-like scales on the skin. The tightness of the skin pulls the skin around the eyes and mouth. This forces the lips and eyelids to turn inside and out, which reveals the red inner lining.

The abdomen and chest of the infant can be severely restricted due to the tightness of the skin. This can make the breathing and eating process difficult. The hands and feet can become swollen and partially flexed.

The ears can appear missing or misshapen but are fused to the head by the thick skin. Other complications in infants include a flat nose, abnormal hearing, decreased joint mobility and frequent respiratory infections.

Infants affected with harlequin ichthyosis also have an increased risk of premature birth. These infants will have low body temperature, high sodium levels in their blood (hypernatremia) and dehydration. Infants will require a tube for feeding to help with the sucking response. Constriction and swelling of the mouth can interfere with the suck response. If the baby’s eyelids are forced to open due to the disorder, the baby’s cornea needs to be protected and lubricated.

Children and adults

Children who survive the initial stages of the disorder develop less severe symptoms. They will have a delay in the developmental milestone, which includes social and motor skills. However, there will be no retardment in the mental health condition.

Children with harlequin ichthyosis will have dry red skin, which will be covered by thin, large scales. Other complications include

• Short stature
• Poor hair growth
• Scaring alopecia
• Unusual facial features
• Reduced hearing
• Thick fingernails
• Heat and cold intolerance
• Contracture of digits

Diagnosis of harlequin ichthyosis

Harlequin ichthyosis is usually diagnosed during birth by the child’s physical appearance. Prenatal testing can be done using a DNA test, and the test will look for the mutations in the ABCA12 gene. In some cases, during the ultrasound, some features of harlequin ichthyosis can be identified.

Treatment and management of harlequin ichthyosis

Currently, there is no cure for harlequin ichthyosis. The treatment will aim to protect the skin and prevent infections that can occur and other complications.

Infants and babies affected with harlequin ichthyosis will require a neonatal intensive care unit (NICU). They will require a tube for feeding to support nutrition and prevent dehydration.

The affected baby will be placed in a humidifier incubator. This will track their temperature, electrolyte levels, respiratory rate and heart rate.

Frequent application of lubrication will be required to protect the eyes and eyelids. The infants will also be administered pain relievers like an opioid to manage the pain caused due to deep cracks. Doctors will also use antibiotics to prevent infections and other complications.

Infants affected with the disorder will require an intensive skincare regime. This will keep their skin moisturised and prevents fissures and cracks that can lead to infection.

Prevention of harlequin ichthyosis

Harlequin ichthyosis cannot be prevented. However, during early pregnancy, DNA tests can help with the identification of the disorder. A small amount of the amniotic fluid will be removed surrounding the foetus, which will help identify the mutated gene.

Conclusion

Harlequin ichthyosis is a rare genetic disorder that affects infants and children. The disorder is usually inherited through the parents, and the affected infants usually live for a few days.

Due to medical intervention, the child can reach early adulthood. The survival rate of harlequin ichthyosis is rising. However, the mortality rate is still high. Infants and children who are surviving will require continuous monitoring and treatment to keep the skin healthy and protected from infections.

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