Ichthyosis Congenita, Harlequin Fetus Type

Alternative Names

  • Harlequin Ichthyosis
  • HI
  • 'Harlequin Fetus'
  • Ichthyosis Fetalis
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WHO-ICD-10 version:2010

Congenital malformations, deformations and chromosomal abnormalities

Other congenital malformations

OMIM Number

242500

Mode of Inheritance

Autosomal recessive

Gene Map Locus

2q34

Description

Harlequin ichthyosis is a keratinization disorder due probably to cutaneous lipid anomalies. It is characterized by hyperkeratosis forming plates and grooves that look like Harlequin's costume. Infants with Harlequin ichthyosis are usually born prematurely and are encased in thick, hard, armor-like plates of cornified skin separated by deep fissures that severely restrict movement. Most infants with Harlequin ichthyosis are born as collodion babies that are born with a taut, shiny, translucent or opaque membrane that encases the entire body and lasts for days to weeks. The taut skin results in deformation of facial features and microcephaly. Affected infants are at risk for life-threatening complications in the postnatal period, such as respiratory distress, dehydration, electrolyte imbalance, temperature instability, feeding problems, and bacterial infections, often with fatal consequences. They usually die within the first weeks of life. However, improved survival into childhood and adolescence has been achieved with intense supportive care and systemic retinoid therapy in the neonatal period. Patients who survive manifest a debilitating, persistent ichthyosis.

Prenatal diagnosis for malignant keratoma had been performed by fetal skin biopsy and electron microscopic observation at 19-23 weeks estimated gestational age. Harlequin ichthyosis is very rare with an incidence of about 1 in 300.000 births.

Molecular Genetics

Harlequin ichthyosis is transmitted as an autosomal recessive trait. The vast majority of individuals with this disorder have mutations in ABCA12 gene, including partial-gene deletions. ABCA12 gene encodes for a protein that belongs to a subfamily of ATP-binding cassette (ABC) transporters. These transporters carry many types of molecules across cell membranes. In particular, the ABCA12 protein plays a major role in transporting lipids in cells of the epidermis. This lipid transport appears to be essential for normal development of the skin. Thus, mutations in this gene probably lead to an absence of ABCA12 protein or the production of an extremely small version of the protein that cannot transport lipids properly. A lack of lipid transport causes numerous problems with the development of the epidermis before and after birth. Specifically, it prevents the skin from forming an effective barrier against fluid loss (dehydration) and infections, and leads to the formation of hard, thick scales characteristic of harlequin ichthyosis.

Epidemiology in the Arab World

View Map
Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
242500.1.1United Arab EmiratesMaleNoYes Scaling skin; Erythroderma; Eclabion; ...NM_173076.2:c.2486dupHomozygousAutosomal, RecessiveBastaki et al. 2017

Other Reports

Egypt

Selim et al. (2000) described a male baby born to a consanguineous Egyptian family with six siblings, four (3 females and 1 male) of whom died because of Harlequin icthyosis.

[Selim MM, Al-Bou-Ainain HH, Al-Ansari H. Harlequin Icthyosis (HI). Gulf J Dermatol. 2000; 7(2): 1-9.]

Lebanon

Megarbane (1998) described a harlequin baby born to consanguineous parents. No other details were available. 

Sudan

Selim et al. (2000) described a consanguineous Sudanese family with two HI affected infants. 

[Selim MM, Al-Bou-Ainain HH, Al-Ansari H. Harlequin Icthyosis (HI). Gulf J Dermatol. 2000; 7(2): 1-9.]

Tunisia

Larguèche et al. (2009) reported the case of a male infant born to consanguineous parents. The infant was covered with massive thick, waxy, plate-like scales and deep fissures. There was striking facial distortion including severe eclabium and ectropion. The baby died at two days of age.

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