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| Harlequin Ichthyosis |
Harlequin
Ichthyosis
Harlequin ichthyosis is a
rare genetic skin disorder. The newborn infant is covered with plates of thick
skin that crack and split apart. The thick plates can pull at and distort
facial features and can restrict breathing and eating. Harlequin infants need
to be cared for in the neonatal intensive care unit immediately. Harlequin
ichthyosis is inherited in an autosomal recessive pattern.
Synonyms
·
harlequin fetus
·
ichthyosis fetalis
·
harlequin baby syndrome
Signs & Symptoms
Infants with Harlequin ichthyosis are covered
in thick plate-like scales of skin. The tightness of the skin pulls around the
eyes and the mouth, forcing the eyelids and lips to turn inside out, revealing
the red inner linings. The chest and abdomen of the infant may be severely
restricted by the tightness of the skin, making breathing and eating difficult.
The hands and feet may be small and swollen, and partially flexed. The ears may
appear to be misshapen or missing, but are really fused to the head by the
thick skin. Infants born with harlequin ichthyosis may also have a flat nose
(depressed nasal bridge), abnormal hearing, frequent respiratory infections,
and decreased joint mobility.
Premature birth is typical, leaving the
infants at risk for complications from early delivery. These infants are also
at high risk for low body temperature, dehydration, and hypernatremia (elevated
levels of sodium in the blood). Constriction and swelling of the mouth may
interfere with the suck response and infants may need tube feeding. The baby’s
corneas need to be lubricated and protected if the eyelids are forced open by
the tightness of the skin.
Causes
Harlequin ichthyosis is caused by changes
(mutations) in the ABCA12 gene, which gives instructions
for making a protein that is necessary for skin cells to develop normally. It
plays a key role in the transport of fats (lipids) to most superficial layer of
the skin (epidermis), creating an effective skin barrier. When this gene is
mutated, the skin barrier is disrupted.
Harlequin ichthyosis is inherited in an
autosomal recessive pattern. Recessive genetic disorders occur when an
individual inherits an abnormal gene from each parent. If an individual
receives one normal gene and one abnormal gene for the disease, the person will
be a carrier for the disease, but usually will not show symptoms. The risk for
two carrier parents to both pass the abnormal gene and, therefore, have an
affected child is 25% with each pregnancy. The risk to have a child who is a
carrier, like the parents, is 50% with each pregnancy. The chance for a child
to receive normal genes from both parents is 25%. The risk is the same for
males and females.
Related Disorders
Symptoms of the following disorder may be
similar to harlequin ichthyosis.
Lamellar ichthyosis is an inherited skin
disorder characterized by broad, dark, plate-like scales separated by deep
cracks. Lamellar ichthyosis may also cause reddened skin (erythroderma),
thickened skin on the palms and soles and decreased sweating with heat
intolerance. (For more information on lamellar ichthyosis, choose “Ichthyosis,
Lamellar” as your search term in the Rare Disease Database.)
Diagnosis
Harlequin ichthyosis is diagnosed at birth
based on the child’s physical appearance. Prenatal testing may be possible by
testing fetal DNA for mutations in the ABCA12 gene. In
addition, some of the features of harlequin ichthyosis maybe seen on ultrasound
during the second trimester and onward.
Standard Therapies
A multi-disciplinary team is involved in the
care of infants with harlequin ichthyosis as soon as they are born. This has
been shown to improve outcomes and reduce complications such as respiratory
distress, dehydration, electrolyte imbalances, impaired thermoregulation,
systemic bacterial infections, and feeding difficulties. Early treatment with
oral retinoids is also thought to improve outcomes. However, they are only used
in severe cases due to their known toxicity and side effects.
The thick, plate-like skin of harlequin type
ichthyosis will gradually split and peel off over several weeks. Antibiotic
treatment may be necessary to prevent infection at this time. Administration of
oral acitretin may accelerate shedding of the thick scales. Most harlequin
infants will need one-on-one nursing care for the first several weeks of life.
After the thick plates peel off, the skin is
left dry and reddened, and may be covered in large thin scales. The skin
symptoms are treated by applying skin softening emollients. This can be
particularly effective after bathing while the skin is still moist. Many
patients with severe ichthyosis exfoliate manually by rubbing off the thick
scale with special exfoliating gloves with a rough surface. Skin barrier repair
formulas containing ceramides or cholesterol, moisturizers with petrolatum or
lanolin, and mild keratolytics (products containing alpha-hydroxy acids or
urea) can all work to keep the skin moisturized and pliable, and prevent
cracking and fissuring that can lead to infection. Removal of damaged tissue
(debridement) from the fingers may be needed if they are constricted by bands
of skin to avoid a loss of circulation.
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