Harlequin-ichthyosis Q80.4

Riecke 1900

Most severe form of autosomal recessive congenital ichthyosis (ARCI). S.u. Ichthyoses.

Very rare form of ichthyosis with a prevalence of 1/1.0 million people

Recessive nonsense mutation in the ABCA12 gene located on chromosome 2q34. The ABCA12 gene encodes a protein called the ATP-binding cassette (ABC) transporter. This protein is involved in lipid transport from lamellar granules to the apical membrane of keratinocytes in the statum granulosum. It is likely that the mutation, either via alteration of the major nucleotide-binding domain or the transmembrane domain of the ABCA12 protein, results in a significant loss of lipid barrier function, leading to the severe ichthyotic skin condition.

Less severe missense mutations of the ABCA12 gene result in a milder variant of autosomal recessive congenital ichthyoses (see ACRI spectrum).

Children are born with extreme, already intrauterine keratinization with armor-like horn plates and deep skin tears (lamellar ichthyosis). The armour-like armour severely impairs the mobility of the infants and also considerably restricts their ability to breathe and eat. The harlequin fetus is born with a flat nose, bulging lips, ectropionated eyelids. Further infestation of oral and genital mucous membrane.

It is important to lubricate the skin several times a day (e.g. kerosene subliq., Linola fat). If the skin is torn, grease gauze with antiseptic additives such as chlorhexidine (e.g. Bactigras gauze dressing). Oil-containing baths and antiseptic additives such as chlorhexidine. Externals containing salicylic acid for extreme hyperkeratotic areas are controversial because of resorptive toxicity; better short term for such areas are up to 10% urea ointments.

Local treatment with tazarotene can be applied to circumscribed areas of skin (< 2% of body surface). S.a.u. Ichthyosis vulgaris, autosomal dominant.

Etretinate therapy (1-3 mg/day in slowly decreasing dosage) is the only medication described as effective. Onset in the first days of life.

Causes of death of initially surviving babies are especially sudden septicemia with rapid deterioration. Therefore, prophylactic broad-spectrum antibiotics, regular smears of the skin, blood checks for bacteremia, and the fastest possible use of antibiotics according to antibiogram, are necessary if infection is suspected.

50% of children die before or shortly after birth due to respiratory insufficiency, heat/water balance disorders and septicaemia. The clinical picture later changes to inflammatory exfoliative ichthyosis and erythroderma.

In long-term survivors the skin armour recedes somewhat. Generalised, coarse lamellar scaling with pronounced inflammatory symptoms (erythrodermia) is observed.

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