Nonsyndromic types of ichthyoses – an update

Authors


  • Section Editor, Prof. Dr. Jan C. Simon, Leipzig

  • The development of ichthyosis is now believed to result from genetic defects affecting the epidermal barrier along with a concomitant homeostatic repair response.

  • Among patients with two filaggrin mutations, about 30% do not have atopy; one filaggrin mutation is sufficient for predisposing patients to atopic eczema or allergic rhinitis.

  • Newborns with harlequin ichthyosis or who are born as a collodion baby are considered a “dermatological emergency” and should be transferred to a neonatal intensive care unit.

  • Patients with ARCI or keratinopathic ichthyosis often have significant vitamin D deficiency.

  • Long daily baths and mechanical keratolysis are essential for patients with severe ichthyosis.

  • Patients should be encouraged to contact and join a self-help organization.

Summary

Ichthyoses are genetically determined Mendelian disorders of cornification (MEDOC) that are characterized by universal scaling. Today we distinguish between non-syndromic and syndromic forms. Ichthyosis vulgaris is the most frequent type (prevalence 1:100) and is caused by autosomal semi-dominant filaggrin mutations. It is associated with a higher risk for the development of atopic diseases, such as atopic eczema and allergic rhinitis. Recessive X-linked ichthyosis (RXLI) occurs almost exclusively in boys; in Germany it has a prevalence of around 1:4,000. It is caused by steroid sulfatase deficiency and is often associated with further clinical problems, such as cryptorchidism (∼20%) or social communication deficits, such as attention deficit hyperactivity syndrome (40%) or autism (25%). Autosomal recessive congenital ichthyosis (ARCI) is genetically very heterogeneous and 8 different genes have been identified so far. The most frequent cause of ARCI is a transglutaminase 1 deficiency (prevalence 1:200, 000). Mutations in keratin genes are the cause of the keratinopathic ichthyoses, such as epidermolytic ichthyosis. They manifest at birth and often feature episodes of blistering. Most of these types are inherited as autosomal dominant traits, but autosomal recessive forms have also been described on occasion.

Ancillary