ICHTHYOSIS: clinical and molecular update. Part 2: syndromic ichthyosis. Diagnostic and therapeutic approach of ichthyosis.

Syndromic ichthyoses are a group of disorders whose genetic alterations impact both epidermal and non-epidermal tissues. Therefore, patients present symptoms in other organs. Most are extraordinary and, in some, ichthyosiform desquamation has been poorly described. Their patterns of inheritance are diverse; their extracutaneous clinical signs, heterogeneous; and the skin symptoms, highly variable, which hinders a proper clinical classification. Ichthyosis diagnosis starts with proper anamnesis, detailed physical examination, and detection of associated analytic and/or histologic findings. Genetic testing is indispensable, not only for diagnostic certainty, but also because understanding the molecular substrate for each patient is the first step towards finding an individualized therapeutic regimen. While it will almost invariably involve facilitating desquamation and maintaining skin hydration using topical exfoliants and emollients, recently, replacement therapies aiming at substituting the proteins and lipids specifically altered in each patient are being developed and gene therapy approaches with the ultimate goal of curing the disease are being assessed. In part 2 of this review, we'll be updating the clinical and genetic findings of syndromic entities, ichthyosis diagnosis and treatment.