Harlequin-type ichthyosis

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Harlequin-type ichthyosis
Harlequin-type ichthyosis
Synonyms	Harlequin ichthyosis, HI
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Specialty	Dermatology, Genetics
Symptoms	Thickened skin, ectropion, eclabium, ear deformities
Complications	Infection, dehydration, respiratory failure
Onset	Birth
Duration	Lifelong
Types	N/A
Causes	Mutations in the ABCA12 gene
Risks	Autosomal recessive inheritance
Diagnosis	Genetic testing, clinical examination
Differential diagnosis	Other forms of ichthyosis
Prevention	Genetic counseling
Treatment	Emollients, retinoids, supportive care
Medication	Acitretin, Isotretinoin
Prognosis	Variable, improved with treatment
Frequency	Rare
Deaths	High mortality in infancy without treatment

Harlequin-type ichthyosis is a severe genetic disorder that affects the skin. It is characterized by thickened skin over most of the body at birth. The skin forms large, diamond-shaped plates separated by deep cracks (fissures). These skin abnormalities affect the shape of the eyelids, nose, mouth, and ears, and limit movement of the arms and legs. Restricted movement of the chest can lead to breathing difficulties and respiratory failure.

Genetics

Genetic inheritance patterns of harlequin-type ichthyosis

Harlequin-type ichthyosis is caused by mutations in the ABCA12 gene, which provides instructions for making a protein that is essential for the normal development of skin cells. This condition 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.

Clinical Features

File:TJOD-14-138-g4.jpg

Clinical presentation of harlequin-type ichthyosis

Infants with harlequin-type ichthyosis are often born prematurely. At birth, the skin is covered with thick, hard scales that can crack and split apart. The eyes, ears, and other facial features may be abnormally shaped. The condition can also affect the shape of the fingers and toes, and can lead to contractures that restrict movement.

Historical Context

File:Illustrated Medicine and Surgery (1888) (14784247353).jpg

Historical illustration of harlequin ichthyosis

The condition was first described in the medical literature in the 18th century. Historical cases often resulted in early death due to complications such as infection and dehydration. Advances in neonatal care and the use of retinoids have improved the prognosis for affected individuals.

Management

File:Manual of antenatal pathology and hygiene - the foetus (1902) (14784556735).jpg

Early medical literature on ichthyosis

Management of harlequin-type ichthyosis involves intensive care in a neonatal unit. Treatment focuses on maintaining skin moisture, preventing infection, and ensuring adequate nutrition. Retinoid therapy, such as acitretin, can help reduce the thickness of the skin and improve its appearance. Multidisciplinary care involving dermatologists, pediatricians, and other specialists is essential.

Prognosis

File:Kyber's case of foetal ichthyosis.jpg

A historical case of fetal ichthyosis

The prognosis for individuals with harlequin-type ichthyosis has improved significantly with advances in medical care. While the condition is life-threatening in the neonatal period, many individuals now survive into childhood and adulthood with appropriate treatment. Long-term management focuses on skin care and monitoring for complications.

See also

• Ichthyosis
• ABCA12
• Autosomal recessive disorder
• Retinoid