Harlequin ichthyosis

Alternate names

Ichthyosis congenita, Harlequin fetus type; Harlequin fetus

Definition

Harlequin ichthyosis is a severe genetic disorder that mainly affects the skin. The newborn infant is covered with plates of thick skin that crack and split apart.

Epidemiology

Its exact incidence is unknown.

Cause

• Harlequin ichthyosis is caused by mutations in the ABCA12 gene.
• This gene provides instructions for making a protein that is essential for the normal development of skin cells.
• This protein plays a major role in the transport of fats (lipids) in the outermost layer of skin (the epidermis).

Gene mutations

• Some mutations in the ABCA12 gene prevent the cell from making any ABCA12 protein, while others lead to the production of an abnormally small version of the protein that cannot transport lipids properly.
• A loss of functional ABCA12 protein disrupts the normal development of the epidermis, resulting in the hard, thick scales characteristic of harlequin ichthyosis.

Inheritance

Autosomal recessive inheritance, a 25% chance

Harlequin ichthyosis is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Signs and symptoms

• 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.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Congenital ichthyosiform erythroderma
• Depressed nasal ridge(Flat nose)
• Ectropion(Eyelid turned out)
• Hearing abnormality(Abnormal hearing)
• Hyperkeratosis
• Recurrent respiratory infections(Frequent respiratory infections)

30%-79% of people have these symptoms

• Eclabion(Outward turned lips)
• Erythroderma
• Limitation of joint mobility(Decreased joint mobility)

5%-29% of people have these symptoms

• Cataract(Clouding of the lens of the eye)
• Dehydration
• Foot polydactyly(Duplication of bones of the toes)
• Hand polydactyly(Extra finger)
• Malignant hyperthermia
• Respiratory insufficiency(Respiratory impairment)
• Self-injurious behavior(Self-injurious behaviour)
• Sudden cardiac death(Premature sudden cardiac death)

Diagnosis

• Yes, harlequin ichthyosis can be diagnosed before birth using either amniocentesis or chorionic villus sampling.
• Both of these procedures are used to obtain a sample of fetal DNA, which can be tested for mutations in the ABCA12 gene.

Treatment

The supportive care such as oxygen therapy, transporting to incubator, using normal saline to cleanse and moist the skin was performed early after birth. .

NIH genetic and rare disease info

• NIH info on Harlequin ichthyosis

Harlequin ichthyosis is a rare disease.

Harlequin ichthyosis Resources
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