Original Article Submitted: 17.1.2019 DOI: 10.1111/ddg.13968 Accepted: 14.6.2019 Conflict of interest None. Spectrum of ichthyoses in an Austrian ichthyosis cohort from 2004 to 2017 : Supporting information for this article is available on the WWW under https://doi.org/10.1111/ddg.13968 Magdalena Seidl-Philipp1, Summary Ulrich A. Schatz2, Background: Ichthyoses are a heterogeneous disease group, which makes clinical Irina Gasslitter3, Verena classification challenging. An ichthyosis cohort at a center for genodermatoses is pre- Moosbrugger- Martinz1, sented in detail. Stefan Blunder1, Anna S. Patients and Methods: Patients with clinically and/or genetically confirmed Schossig2, Johannes Zschocke2, ichthyosis seen from 2004 to 2017 and listed in a database were included. Disease on- Matthias Schmuth1, set, phenotype, histology, comorbidities and family history were described in detail. Robert Gruber1 In genetically tested patients, the prevalence of various ARCI genes, ARCI phenoty- pes and syndromic ichthyoses, as well as genotype-phenotype correlation and year/ (1) Department of Dermatology, method of genetic testing was assessed. Venereology and Allergology, Medical Results : Of all 198 patients who were included in the cohort, 151 were genetically tested. University of Innsbruck, Innsbruck, 81 had ichthyosis vulgaris, 43 X-linked ichthyosis, 38 autosomal recessive congenital Austria ichthyosis (ARCI), 9 keratinopathic ichthyosis (KPI) and one exfoliative ichthyosis. 26 (2) Department of Human Genetics, individuals suffered from syndromic ichthyoses. A good genotype-phenotype corre- Medical University of Innsbruck, lation was observed for common ichthyoses and KPI; the correlation was less good Innsbruck, Austria in syndromic ichthyoses. In 91 % of ARCI patients an accurate diagnosis was obtained (3) Department of Internal Medicine by genetic testing. In only 33 % of syndromic ichthyoses was the definitive diagnosis II, Medical University of Innsbruck, suspected before genetic testing, which revealed a causative mutation in 86 % of cases. Innsbruck, Austria Conclusion: This study describes the spectrum of ichthyoses in a center of expertise and shows that genetic testing should become a diagnostic standard for this disease group. Introduction X-linked ichthyosis is caused by deletions of the STS gene, resulting in steroid sulfatase deficiency [5]. The phe- Inherited ichthyoses belong to a heterogenous group of notype manifests soon after birth and is characterized by Mendelian disorders of cornification and are divided into generalized brownish scaling, accentuated on the extensor nonsyndromic forms limited to the skin and syndromic aspects. Interestingly, the prevalence of FLG mutations is forms with involvement of skin and other organs. Nonsyn- increased in individuals with XLI [6]. dromic forms include common ichthyoses such as ichthyosis The clinical presentation and severity of ARCI ranges vulgaris (IV) and X-linked ichthyosis (XLI), as well as rare from harlequin ichthyosis (HI) to lamellar ichthyosis (LI), forms such as autosomal recessive ichthyosis (ARCI), kerati- congenital ichthyosiform erythroderma (CIE), and pleo- nopathic ichthyosis (KPI) and others [1]. morphic ichthyosis (PI), the latter defined as spontaneous Ichthyosis vulgaris is caused by loss-of-function muta- age- dependent phenotype improvement with mild residual tions in the FLG (filaggrin) gene [2], resulting in an im- scaling in adulthood [1, 7]. Most babies are born with a paired epidermal barrier [3]. Histologically, the granular collodion membrane [1, 8]. Twelve causative genes for ARCI layer is absent or reduced. The phenotype appears within are known currently [7–22]. the first year of life and includes generalized fine scaling, Keratinopathic ichthyosis is caused by mutations in palmoplantar hyperlinearity, and keratosis pilaris. There is a keratin genes, resulting in epidermolysis of keratinocytes predisposition to atopic manifestations [4]. and impaired extracellular lipid membrane formation [23]. © 2019 The Authors. Journal der Deutschen Dermatologischen Gesellschaft published by John Wiley & Sons Ltd on behalf of Deutsche Dermatologische Gesellschaft. | JDDG | 1610-0379/2019/ 1 This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. Original Article Spectrum of ichthyoses Mutations in KRT1, KRT2, and KRT10 result in generali- Severe dermatitis, multiple allergies and metabolic was- zed phenotypes characterized by age-related and ichthyo- ting (SAM) syndrome is caused by either biallelic mutations sis-type-specific erythroderma, blistering and hyperkerato- in DSG1 or a specific heterozygous missense mutation in sis. Keratinopathic ichthyosis mainly includes epidermolytic DSP [45, 46]. ichthyosis (EI), superficial epidermolytic ichthyosis (SEI), Sjögren-Larsson syndrome (SLS) presents mainly with mosaic forms of EI, and ichthyosis with confetti (IWC) congenital ichthyosis, spastic diplegia or tetraplegia and mild [8, 24–27]. to moderate mental retardation. It is due to biallelic muta- Peeling skin syndrome (PSS) is characterized by superfi- tions in ALDH3A2, encoding the fatty aldehyde dehydro- cial exfoliation of the epidermis. One subtype of PSS is auto- genase, leading to accumulation of long-chain aliphatic al- somal recessive exfoliative ichthyosis (AREI) with mutations cohols [47, 48]. in CSTA [28, 29]. Classification of an ichthyosis patient to a distinct form Syndromic ichthyoses present with generalized scaling of of ichthyosis is challenging even for specialists. Clinical- the skin and variable involvement of other tissues or systems ly-based algorithms are instrumental in narrowing down [1, 30]. Our cohort included eight different subtypes: the differential diagnosis [30]. As the genetic basis of most Netherton syndrome (NS) [1] is caused by biallelic muta- ichthyoses is now known, genetic testing becomes the stan- tions in SPINK5, which encodes the serine protease inhibitor dard procedure for confirmation of the clinical differential LEKTI. The stratum corneum thickness is reduced because diagnosis in rare ichthyoses. of accelerated proteolysis of corneodesmosomes by kallik- An ichthyosis cohort is analyzed in this retrospective stu- reins [31]. Netherton syndrome usually manifests at birth dy from a center of expertise. with CIE and later presents with ichthyosis linearis circum- flexa, hair shaft abnormalities, failure to thrive, and atopy Materials and Methods with high IgE-levels [32]. Neutral lipid storage disease with ichthyosis (NLSDI) Human subjects encodes an acyltransferase involved in long-chain fat- ty-acid-oxidation and which deficiency results in an accumu- This retrospective analysis included all individuals with cli- lation of triglycerides in leukocytes, muscle cells, hepatocytes nically suspected or genetically confirmed ichthyoses who and fibroblasts [33]. It is characterized by generalized ichthyo- were seen in the outpatient department for genodermatoses sis, hepatosplenomegaly, myopathy and cataract [34–36]. in Innsbruck, Austria, between 2004 and 2017. Disease on- Keratitis-ichthyosis-deafness (KID) syndrome is charac- set, phenotype, histology, comorbidities and family histo- terized by erythroderma, leathery skin, palmoplantar kerato- ry were described in detail for all patients. Only data from derma, keratitis, and sensorineural deafness [37]. It is caused genetically tested patients were used for relevant statistical by mutations in GJB2, encoding the gap junction protein analysis. The clinical diagnosis of ichthyosis was made by connexin-26 [38]. two experienced dermatologists (RG, MS) in accordance Autosomal recessive keratoderma ichthyosis deafness with the current disease classification [1]. The study was (ARKID) syndrome, characterized by palmoplantar kera- conducted according to the principles of the Declaration of toderma, generalized mild ichthyosis and sensorineural de- Helsinki, and written informed consent was obtained from afness was recently associated with mutations in VPS33B. all patients/parents. The encoded class-C vacuolar protein is involved in sorting of intracellular molecules to late endosomes and lysosomes, Light microscopy and immunohistochemistry and finally in collagen modification [39]. Ichthyosis prematurity syndrome (IPS), which is charac- We found histological results in our operating system for 79 of terized by preterm birth and erythrodermic skin with thick 198 patients. Punch biopsies were fixed in 4 % formaldehyde, vernix caseosa-like scales on the scalp, is caused by biallelic paraffin-embedded, sectioned, and stained with hematoxy- mutations in SLC27A4, encoding the fatty acid transporter lin-eosin stain. Semithin-sections for electron microscopy protein 4 [40]. were stained with toluidine blue. For immunohistochemis- The common features of trichothiodystrophy (TTD) try, paraffin-embedded sections were stained with monoclo- comprise sulfur-deficient brittle hair (tiger-tail-pattern in nal mouse/anti-human FLG-antibody (1 : 50; Novocastra polarized light), dystrophic nails, and photosensitivity [41]. Laboratories Ltd, UK), using the automated preparation Trichothiodystrophy in association with ichthyosis is usually system BenchMark XT (Ventana Medical Systems) and the due to mutations in ERCC2 or ERCC3, encoding helicase high-temperature antigen unmasking technique