Management of Ichthyosis: A Brief Review

Allison L. Limmer, BS, BA; Crystal E. Nwannunu, BS; Ravi R. Patel, MD; Uyen N. Mui, MD; Stephen K. Tyring, MD, PhD

Disclosures

Skin Therapy Letter. 2020;25(1):5-7. 

In This Article

Pathogenesis

As previously mentioned, the ichthyoses, or disorders of keratinization, are characterized by hyperproliferation triggered by increased transepidermal water loss.[2] The distinctive horny layer can be localized or diffuse and may be complicated by hypohidrosis, erythema, and infection. Although occasionally acquired, ichthyosis is largely an inherited condition with over 50 genes implicated in its pathogenesis. These genes influence a variety of cellular functions from DNA repair to adhesion, with the end result being a dysfunctional epidermal barrier.[2] The common ichthyoses are ichthyosis vulgaris and X-linked recessive ichthyosis, both of which are caused by well-characterized genetic mutations.[2,4] Ichthyosis vulgaris occurs due to autosomal dominant mutations in the filaggrin gene (FLG), and X-linked recessive ichthyosis results from alterations in the STS gene, which encodes steroid sulfatase.[2,4] Harlequin ichthyosis, lamellar ichthyosis, and congenital ichthyosiform erythroderma all result from autosomal recessive mutations.[2] Harlequin ichthyosis is associated with homozygous loss of function mutations in ABCA12, which encodes an ATP-binding cassette transporter.[2] Lamellar ichthyosis, congenital ichthyosiform erythroderma, and others exist on a spectrum of autosomal recessive congenital ichthyoses characterized by mutations in TGM1, NIPAL4/ICHTHYIN, ALOX12B, ALOXE3, CYP4F22, ABCA12, PNPLA1, CERS3, LIPN, SDR9C7, and SULT2B1.[2,5–7] Understanding the impact of genetics in the pathogenesis of the ichthyoses gives perspective as to why these diseases often present in infancy or childhood, why they are lifelong burdens to those affected, and why finding a cure presents a challenge.

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