Loss-of-function mutations in filaggrin gene associate with psoriasis vulgaris in Chinese population

Identification of potential susceptibility genes in patients with primary Sjögren's syndrome-associated pulmonary arterial hypertension through whole exome sequencing

BACKGROUND

Pulmonary arterial hypertension (PAH) is a rare complication of primary Sjögren's syndrome (pSS). Several genes have proven to be associated with pSS and PAH. However, there is no study specifically addressing the genetic susceptibility in pSS combined with PAH.

METHODS

Thirty-four unrelated patients with pSS-PAH were recruited from April 2019 to July 2021 at Peking Union Medical College Hospital. Demographic and clinical data were recorded in detail, and peripheral blood samples were collected for whole-exome sequencing (WES). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed to predict the functional effect of mutant genes. Genetic variants identified by WES were confirmed by polymerase chain reaction (PCR)-Sanger sequencing.

RESULTS

We totally identified 141 pathogenic variant loci of 129 genes in these 34 pSS-PAH patients, using WES analysis. Patients with a family history of rheumatic diseases are more likely to carry FLG mutations or carry gene variations related to the biosynthesis of the amino acids pathway (p < 0.05). According to Sanger sequencing confirmation and pathogenicity validation, we totally identified five candidate pathogenic variants including FLG c.12064A > T, BCR c.3275_3278dupCCGG, GIGYF2 c.3463C > A, ITK c.1741C > T, and SLC26A4 c.919-2A > G.

CONCLUSION

Our findings provide preliminary data of exome sequencing to identify susceptibility loci for pSS-PAH and enriched our understanding of the genetic etiology for pSS-PAH. The candidate pathogenic genes may be the potential genetic markers for early warning of this disease.

Overlapping Features of Psoriasis and Atopic dermatitis: From Genetics to Immunopathogenesis to Phenotypes

Psoriasis (PSO) and atopic dermatitis (AD) were once considered to be mutually exclusive diseases, but gradually regarded as a spectrum of disease. Shared genetic loci of both diseases were noted in some populations, including Chinese. Shared immunopathogenesis involving Th17, Th1, Th22 cells, or even IL-13 was found in certain stages or phenotypes. This review discusses the overlapping genetic susceptibility, shared cytokines, immune-mediated comorbidities, and clinical presentations. Overlapping conditions could be classified into mainly PSO lesions with AD features or vice versa, concomitant PSO and AD, or disease transformation as a result of biologics treatment.

Use of Cytokine Mix-, Imiquimod-, and Serum-Induced Monoculture and Lipopolysaccharide- and Interferon Gamma-Treated Co-Culture to Establish In Vitro Psoriasis-like Inflammation Models

Psoriasis (Ps), commonly perceived as a skin and joint disorder, has a complex basis and results from disturbances in the sophisticated network between skin and the immune system. This makes it difficult to properly depict the complete pathomechanism on an in vitro scale. Deciphering the complicated or even subtle modulation of intra- and intercellular factors, assisted by the implementation of in vitro human skin models, may provide the opportunity to dissect the disease background step by step. In addition to reconstructed artificial skin substitutes, which mimic the native physiological context, in vitro models are conducive to the broad "3 Rs" philosophy (reduce, refine, and replace) and represent important tools for basic and applied skin research. To meet the need for a more comprehensive in vitro Ps model, a set of various experimental conditions was applied in this study. The selection of in vitro treatment that mimicked the Ps phenotype was illustrated by analyses of discriminating biomarker genes involved in the pathogenesis of the disease, i.e., keratinocyte differentiation markers, antimicrobial peptides, chemokines, and proliferation markers. This resulted in a reproducible protocol for the use of the primary skin keratinocyte (pKC) monoculture treated with a cytokine cocktail (5MIX, i.e., interleukin (IL) 1 alpha (IL-1α), IL-17A, IL-22, oncostatin M (OSM), and tumour necrosis factor alpha (TNF-α)) at a calcium (Ca2+) concentration (i.e., 2 mM) in an applied medium, which best mirrored the in vitro Ps-like inflammatory model. In addition, based on waste skin material, the method has the potential for extensive experimentation, both in detailed molecular studies and preclinical tests.

A loss of function mutation in the filaggrin gene associated with ichthyosis vulgaris and rheumatoid arthritis

Introduction

Mutations in the filaggrin ( FLG) gene are known to cause ichthyosis vulgaris.

Methods

We used whole-genome sequencing (WGS) technology to investigate the genetic causes of rare and complex inherited diseases including rheumatoid arthritis, ichthyosis, and congenital fibrosis of the extraocular muscles type 1 (CFEOM1) in a Chinese family. WGS was performed in four topics, and the identified candidate mutations were further verified through Sanger sequencing.

Results

We identified a mutation in FLG gene (g.152280098 C>A, p.E2422∗) that may be associated with ichthyosis and arthritis. Moreover, a mutation in KIF21A (g.39726207 G>A, p.R954 W) was also determined in affected members as the cause of CFEOM1. The gene interaction network demonstrated an interesting correlation between FLG and genes associated with arthritis and ichthyosis. Functional enrichment analysis of these interacting genes revealed several possible pathways that might be linked to arthritis and ichthyosis.

Conclusion

In general, we confirmed a loss of function mutation in the FLG gene associated with ichthyosis vulgaris and rheumatoid arthritis in this family.

Influence of Genetic Polymorphisms on Response to Biologics in Moderate-to-Severe Psoriasis

Psoriasis is a chronic inflammatory skin pathology of autoimmune origin and unknown etiology. There are various therapies for treating it, including a wide range of biopharmaceuticals indicated in moderate-to-severe psoriasis. Depending on their therapeutic target, they are classified as tumor necrosis factor inhibitors (anti-TNF) or cytokine inhibitors (interleukin-12, 23, and 17 antagonists). Although they have proved effective and safe, in clinical practice, many patients show a short- and long-term suboptimal response and even varying degrees of toxicity. This variability in response may be influenced by genetic factors, such as polymorphisms in the genes involved in the pathological environment, metabolism or mechanism of action of the drug that could affect the effectiveness and toxicity of biological therapies. This review assesses pharmacogenetic studies of the impact of genetic factors on response to biopharmaceuticals and toxicity in patients diagnosed with moderate-to-severe psoriasis. The results suggest that polymorphisms detected in the HLA genes, in genes that encode cytokines (TNF, IL genes, TNFAIP3), transporters (PDE3A-SLCO1C1, SLC12A8), receptors (TNFRSF1B, CD84, FCGR2A and FCGR3A, IL17RA, IL23R, TLR genes, PGLYRP4) and associated proteins (TNFAIP3, LY96, TIRAP, FBXL19), as well as other genes implicated in the pathogenesis of psoriasis (CDKAL1, CARD14, PTTG1, MAP3K1, ZNF816A, GBP6, CTNNA2, HTR2A, CTLA4, TAP1) can be used in the future as predictive markers of treatment response and/or toxicity with biological therapies in patients diagnosed with moderate-to-severe psoriasis, tailoring treatment to the individual patient.

Insights into interplay of immunopathophysiological events and molecular mechanistic cascades in psoriasis and its associated comorbidities

Psoriasis is an inflammatory skin disease with complex pathogenesis and multiple etiological factors. Besides the essential role of autoreactive T cells and constellation of cytokines, the discovery of IL-23/Th17 axis as a central signaling pathway has unraveled the mechanism of accelerated inflammation in psoriasis. This has provided insights into psoriasis pathogenesis and revolutionized the development of effective biological therapies. Moreover, genome-wide association studies have identified several candidate genes and susceptibility loci associated with this disease. Although involvement of cellular innate and adaptive immune responses and dysregulation of immune cells have been implicated in psoriasis initiation and maintenance, there is still a lack of unifying mechanism for understanding the pathogenesis of this disease. Emerging evidence suggests that psoriasis is a high-mortality disease with additional burden of comorbidities, which adversely affects the treatment response and overall quality of life of patients. Furthermore, changing trends of psoriasis-associated comorbidities and shared patterns of genetic susceptibility, risk factors and pathophysiological mechanisms manifest psoriasis as a multifactorial systemic disease. This review highlights the recent progress in understanding the crucial role of different immune cells, proinflammatory cytokines and microRNAs in psoriasis pathogenesis. In addition, we comprehensively discuss the involvement of various complex signaling pathways and their interplay with immune cell markers to comprehend the underlying pathophysiological mechanism, which may lead to exploration of new therapeutic targets and development of novel treatment strategies to reduce the disastrous nature of psoriasis and associated comorbidities.

A novel method for noninvasive diagnosis of monogenic diseases from circulating fetal cells

OBJECTIVE

To establish a method for noninvasive fetal cell isolation from maternal blood and prenatal testing of monogenic diseases by a combination of direct sequencing and targeted NGS-based SNP haplotyping from single fetal cells.

METHOD

Peripheral blood of pregnant women in two families (congenital deafness and ichthyosis) was collected. After density-based separation and immunostaining with multiple biomarkers, candidate fetal cells were identified by high-throughput imagine analysis and picked up by automation. Individual fetal cells were subjected to STR-genotyping to identify their origin. Pathogenic mutations were identified by direct Sanger sequencing, and a combination of targeted NGS and SNP haplotyping using a custom panel. All the results were compared with amniotic fluid DNA.

RESULTS

Fetal trophoblasts were successfully harvested from maternal blood. STR-genotyping confirmed the fetal origin. Direct sequencing of pathogenic genetic mutations in fetal cells showed consistent results with amniotic fluid samples. For congenital deafness family, NGS-based SNP haplotyping also correctly identified the fetal haplotype. This single cell haplotyping method can be used to diagnose various genetic diseases.

CONCLUSION

We have established a method for noninvasive prenatal testing of monogenic diseases from circulating trophoblast cells. This cell-based NIPT can be further applied to the prenatal diagnosis of various monogenic diseases.

Filaggrin gene mutations with special reference to atopic dermatitis

Purpose of review

Mutations in the Filaggrin gene can cause absent or reduced filaggrin protein, leading to impaired keratinization and skin barrier defect, which produce characteristic phenotypes. In this short review, we report current evidence on the topic with special reference to atopic dermatitis, suggest future directions, and discuss therapeutic implications.

Recent findings

Numerous candidate gene association studies, genome-wide association studies, studies on copy number variations and most recently, sequencing studies, have confirmed the robust association of mutations in the Filaggrin gene with atopic dermatitis, and have also linked these mutations with several other disorders.

Summary

Filaggrin gene defects remain the strongest identified genetic risk factors for atopic dermatitis. Taken in conjunction with other genes found to be associated with this condition, genetic screening and identification of individuals at risk for atopic dermatitis could lead to personalized therapy. Manipulation of genetic regulatory elements to increase the amount of filaggrin protein in deficient individuals is an attractive treatment option for the future.

A ligand-based system for receptor-specific delivery of proteins

Gene delivery using vector or viral-based methods is often limited by technical and safety barriers. A promising alternative that circumvents these shortcomings is the direct delivery of proteins into cells. Here we introduce a non-viral, ligand-mediated protein delivery system capable of selectively targeting primary skin cells in-vivo. Using orthologous self-labelling tags and chemical cross-linkers, we conjugate large proteins to ligands that bind their natural receptors on the surface of keratinocytes. Targeted CRE-mediated recombination was achieved by delivery of ligand cross-linked CRE protein to the skin of transgenic reporter mice, but was absent in mice lacking the ligand's cell surface receptor. We further show that ligands mediate the intracellular delivery of Cas9 allowing for CRISPR-mediated gene editing in the skin more efficiently than adeno-associated viral gene delivery. Thus, a ligand-based system enables the effective and receptor-specific delivery of large proteins and may be applied to the treatment of skin-related genetic diseases.

Smart identification of psoriasis by images using convolutional neural networks: a case study in China

BACKGROUND

Psoriasis is a chronic inflammatory skin disease, which holds a high incidence in China. However, professional dermatologists who can diagnose psoriasis early and correctly are insufficient in China, especially in the rural areas. A smart approach to identify psoriasis by pictures would be highly adaptable countrywide and could play a useful role in early diagnosis and regular treatment of psoriasis.

OBJECTIVES

Design and evaluation of a smart psoriasis identification system based on clinical images (without relying on a dermatoscope) that works effectively similar to a dermatologist.

METHODS

A set of deep learning models using convolutional neural networks (CNNs) was explored and compared in the system for automatic identification of psoriasis. The work was carried out on a standardized dermatological dataset with 8021 clinical images of 9 common disorders including psoriasis along with full electronic medical records of patients built over the last 9 years in China. A two-stage deep neural network was designed and developed to identify psoriasis. In the first stage, a multilabel classifier was trained to learn the visual patterns for each individual skin disease. In the second stage, the output of the first stage was utilized to distinguish psoriasis from other skin diseases.

RESULTS

The area under the curve (AUC) of the two-stage model reached 0.981 ± 0.015, which outperforms a single-stage model. And, the classifier showed superior performance (missed diagnosis rate: 0.03, misdiagnosis rate: 0.04) than 25 Chinese dermatologists (missed diagnosis rate: 0.19, misdiagnosis rate: 0.10) in the diagnosis of psoriasis on 100 clinical images.

CONCLUSIONS

Using clinical images to identify psoriasis is feasible and effective based on CNNs, which also builds a solid technical base for smart care of skin diseases especially psoriasis using mobile/tablet applications for teledermatology in China.

Water-Soluble Extract from Actinidia arguta (Siebold & Zucc.) Planch. ex Miq. and Perilla frutescens (L.) Britton, ACTPER, Ameliorates a Dry Skin-Induced Itch in a Mice Model and Promotes Filaggrin Expression by Activating the AhR Signaling in HaCaT Cells

With a complex etiology involving multiple factors, the condition known as itch is a primary symptom of many skin diseases. Current treatment methods are ineffective for addressing itches caused by dry skin, for example. We developed a botanical extract, ACTPER, made from a mixture of Actinidia arguta and Perilla frutescens, which have traditionally been used to treat itch. The quality of ACTPER as a research agent was controlled in our experiment by cell-based bioassays, as well as by high-performance liquid chromatography (HPLC), using two chemical markers. In the acetone-induced dry skin mice model, the oral administration of ACTPER alleviated dry skin-related skin properties and itching behavior. The RNA and protein expression of the filament aggregating protein (filaggrin) gene, a key factor involved in the regulation of skin barrier function, was significantly increased, as measured by quantitative reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence assay. To understand the underlying mechanism(s) at the molecular level, HaCaT cells, a human keratinocyte-derived cell line, were treated with various concentrations of ACTPER. We found that the protein expression of filaggrin was indeed upregulated by ACTPER in a dose dependent manner. Data from experiments involving the reporter plasmid containing the xenobiotic response element (XRE), and the chemical antagonist for the aryl hydrocarbon receptor (AhR), indicated that the ACTPER-mediated upregulation of filaggrin was controlled through the activation of the AhR signaling pathway. The molecular docking simulation study predicted that ACTPER might contain chemical compounds that bind directly to AhR. Taken together, our results suggest that ACTPER may provide the platform, based upon which a variety of safe and effective therapeutic agents can be developed to treat itch.

Genetic Study on Small Insertions and Deletions in Psoriasis Reveals a Role in Complex Human Diseases

Genetic studies based on single-nucleotide polymorphisms have provided valuable insights into the genetic architecture of complex diseases. However, a large fraction of heritability for most of these diseases remains unexplained, and the impact of small insertions and deletions (InDels) has been neglected. We performed a comprehensive screen on the exome sequence data of 1,326 genes using the SOAP-PopIndel method for InDels in 32,043 Chinese Han individuals and identified 29 unreported InDels within 25 susceptibility genes associated with psoriasis. Specifically, we identified 12 common, 9 low-frequency, and 8 rare InDels that explained approximately 1.29% of the heritability of psoriasis. Further analyses identified KIAA0319, RELN, NCAPG, ABO, AADACL2, LMAN1, FLG, HERC5, CCDC66, LEKR1, AFF3, ABCG2, ANXA7, SYTL2,GIPR, METTL1, and FYCO1 as unreported genes for psoriasis. In addition, identified InDels were associated with the following reported genes: IFIH1, ERAP1, ERAP2, LNPEP, UBLCP1, and STAT3; unreported independent associations for exonic InDels were found within GJB2 and ZNF816A. Our study enriched the genetic basis and pathogenesis of psoriasis and highlighted the non-negligible impact of InDels on complex human diseases.

Whole exome sequencing identified two point mutations of COL7A1 and FLG in a Chinese family with dystrophic epidermolysis bullous pruriginosa and ichthyosis vulgaris

We report a 21-year-old man with recurrent bullous eruptions and severe itching on the lower legs and feet since 5 years of age. Dry, dirty brown, tile-like scales covered his lower legs with dystrophic toenails. Nodular prurigo-like lesions, scarring papules and milia remitted after the bullous eruptions. His father and another two family members had similar but mild presentations with recurrent bullae on the lower legs. Whole exome sequencing detected the heterozygous variants of COL7A1 c.6698G>A and FLG c.7249C>T in this pedigree. COL7A1 c.6698G>A was reported in bullous dermolysis of the newborn and FLG c.7249C>T was reported in ichthyosis vulgaris. Thus, the diagnosis of dystrophic epidermolysis bullosa pruriginosa associated with ichthyosis vulgaris was made.

Steroid sulfatase and filaggrin mutations in a boy with severe ichthyosis, elevated serum IgE level and moyamoya syndrome

X-linked ichthyosis (XLI) is a relatively common, recessive condition caused by mutations in the steroid sulfatase (STS) gene. Common loss-of-function mutations in the filaggrin gene (FLG) cause ichthyosis vulgaris and predispose individuals to atopic eczema. We report a case of a 6-year-old boy who presented with unusually severe XLI, an increased serum immunoglobulin E level (2120IU/ml) and moyamoya angiopathy. Whole-exome sequencing identified a gross deletion encompassing the STS in Xp22.31 and the p.K4022X FLG mutation. The deletion is at least 1.6Mb in size in the proband, based on real-time quantitative polymerase chain reaction results. No other genetic mutations related to ichthyosis, moyamoya or hyper-immunoglobulin E syndrome were detected. Furthermore, his mother's brothers suffered from mild XLI and only had a deletion encompassing the STS. Additionally, his father and older sister suffered from mild ichthyosis vulgaris and had the p.K4022X FLG mutation. We report the first case of XLI with concurrent moyamoya syndrome. Moreover, an IgE-mediated immune response may have triggered the moyamoya signaling cascade in this patient with ichthyosis. Furthermore, our study strengthens the hypothesis that filaggrin defects can synergize with an STS deficiency to exacerbate the ichthyosis phenotype in an ethnically diverse population.

Development of Unlabeled Probe Based High-Resolution Melting Analysis for Detection of Filaggrin Gene Mutation c.3321delA

BACKGROUND

Filaggrin gene (FLG) plays an important role in skin barrier function, and loss-of-function mutations of FLG have been shown to be a predisposing factor for atopic dermatitis (AD). The c.3321delA mutation is the most common FLG mutation in Chinese population. We aim to develop a rapid, cost-efficiency, and reliable closed-tube method that has not been described for the detection of c.3321delA mutation.

METHODS

Recombinant wild-type and mutant plasmids of c.3321delA mutation were constructed, heterozygous mutant plasmids were prepared by mixing the mutant plasmids and wild-type plasmids at 1:1 ratio. High-resolution melting analysis (HRMA) coupled with an unlabeled DNA probe was employed to identify the shift in melting temperature of the probe-template complex, which reflects the presence of c.3321delA mutation.

RESULTS

Unlabeled probe based HRMA was able to distinguish all three genotypes (wild-type, heterozygote, and mutant) of c.3321delA mutation. Then, we applied this method to genotype 1,317 clinical samples. Genotyping results obtained from unlabeled probe HRMA were 100% concordant with the results from direct sequencing.

CONCLUSION

We developed a fast and high-throughput method to detect the c.3321delA mutation.

Current knowledge on psoriasis and autoimmune diseases

Psoriasis is a prevalent, chronic inflammatory disease of the skin, mediated by crosstalk between epidermal keratinocytes, dermal vascular cells, and immunocytes such as antigen presenting cells (APCs) and T cells. Exclusive cellular “responsibility” for the induction and maintenance of psoriatic plaques has not been clearly defined. Increased proliferation of keratinocytes and endothelial cells in conjunction with APC/T cell/monocyte/macrophage inflammation leads to the distinct epidermal and vascular hyperplasia that is characteristic of lesional psoriatic skin. Despite the identification of numerous susceptibility loci, no single genetic determinant has been identified as responsible for the induction of psoriasis. Thus, numerous other triggers of disease, such as environmental, microbial and complex cellular interactions must also be considered as participants in the development of this multifactorial disease. Recent advances in therapeutics, especially systemic so-called “biologics” have provided new hope for identifying the critical cellular targets that drive psoriasis pathogenesis. Recent recognition of the numerous co-morbidities and other autoimmune disorders associated with psoriasis, including inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus suggest common signaling elements and cellular mediators may direct disease pathogenesis. In this review, we discuss common cellular pathways and participants that mediate psoriasis and other autoimmune disorders that share these cellular signaling pathways.

Genetic and epigenetic basis of psoriasis pathogenesis

Psoriasis is a chronic inflammatory skin disease whose prevalence varies among different populations worldwide. It is a complex multi-factorial disease and the exact etiology is largely unknown. Family based studies have indicated a genetic predisposition; however they cannot fully explain the disease pathogenesis. In addition to genetic susceptibility, environmental as well as gender and age related factors were also been found to be associated. Recently, imbalances in epigenetic networks are indicated to be causative elements in psoriasis. The present knowledge of epigenetic involvement, mainly the DNA methylation, chromatin modifications and miRNA deregulation is surveyed here. An integrated approach considering genetic and epigenetic anomalies in the light of immunological network may explore the pathogenesis of psoriasis.

Molecular biology of atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with specific genetic and immunological mechanisms. The rapid development of new techniques in molecular biology had ushered in new discoveries on the role of cytokines, chemokines, and immune cells in the pathogenesis of AD. New polymorphisms of AD are continually being reported in different populations. The physical and immunological barrier of normal intact skin is an important part of the innate immune system that protects the host against microbials and allergens that are associated with AD. Defects in the filaggrin gene FLG may play a role in facilitating exposure to allergens and microbial pathogens, which may induce Th2 polarization. Meanwhile, Th22 cells also play roles in skin barrier impairment through IL-22, and AD is often considered to be a Th2/Th22-dominant allergic disease. Mast cells and eosinophils are also involved in the inflammation via Th2 cytokines. Release of pruritogenic substances by mast cells induces scratching that further disrupts the skin barrier. Th1 and Th17 cells are mainly involved in chronic phase of AD. Keratinocytes also produce proinflammatory cytokines such as thymic stromal lymphopoietin (TSLP), which can further affect Th cells balance. The immunological characteristics of AD may differ for various endotypes and phenotypes. Due to the heterogeneity of the disease, and the redundancies of these mechanisms, our knowledge of the pathophysiology of the disease is still incomplete, which is reflected by the absence of a cure for the disease.

Mitochondrial dysfunction: a neglected component of skin diseases

Aberrant mitochondrial structure and function influence tissue homeostasis and thereby contribute to multiple human disorders and ageing. Ten per cent of patients with primary mitochondrial disorders present skin manifestations that can be categorized into hair abnormalities, rashes, pigmentation abnormalities and acrocyanosis. Less attention has been paid to the fact that several disorders of the skin are linked to alterations of mitochondrial energy metabolism. This review article summarizes the contribution of mitochondrial pathology to both common and rare skin diseases. We explore the intriguing observation that a wide array of skin disorders presents with primary or secondary mitochondrial pathology and that a variety of molecular defects can cause dysfunctional mitochondria. Among them are mutations in mitochondrial- and nuclear DNA-encoded subunits and assembly factors of oxidative phosphorylation (OXPHOS) complexes; mutations in intermediate filament proteins involved in linking, moving and shaping of mitochondria; and disorders of mitochondrial DNA metabolism, fatty acid metabolism and heme synthesis. Thus, we assume that mitochondrial involvement is the rule rather than the exception in skin diseases. We conclude the article by discussing how improving mitochondrial function can be beneficial for aged skin and can be used as an adjunct therapy for certain skin disorders. Consideration of mitochondrial energy metabolism in the skin creates a new perspective for both dermatologists and experts in metabolic disease.

Ichthyosis vulgaris: the filaggrin mutation disease

Ichthyosis vulgaris is caused by loss-of-function mutations in the filaggrin gene (FLG) and is characterized clinically by xerosis, scaling, keratosis pilaris, palmar and plantar hyperlinearity, and a strong association with atopic disorders. According to the published studies presented in this review article, FLG mutations are observed in approximately 7·7% of Europeans and 3·0% of Asians, but appear to be infrequent in darker-skinned populations. This clinical review article provides an overview of ichthyosis vulgaris epidemiology, related disorders and pathomechanisms. Not only does ichthyosis vulgaris possess a wide clinical spectrum, recent studies suggest that carriers of FLG mutations may have a generally altered risk of developing common diseases, even beyond atopic disorders. Mechanistic studies have shown increased penetration of allergens and chemicals in filaggrin-deficient skin, and epidemiological studies have found higher levels of hand eczema, irritant contact dermatitis, nickel sensitization and serum vitamin D levels. When relevant, individuals should be informed about an increased risk of developing dermatitis when repeatedly or continuously exposed to nickel or irritants. Moreover, with our current knowledge, individuals with ichthyosis vulgaris should be protected against neonatal exposure to cats to prevent atopic dermatitis and should abstain from smoking to prevent asthma. Finally, they should be advised against excessive exposure to factors that decrease skin barrier functions and increase the risk of atopic dermatitis.

Study of the genetic factors predisposing to the development of psoriasis

Background papers on psoriasis epidemiology, pathogenesis and genetics are presented. Special attention is given to genetic factors of the aptitude to psoriasis development. Were analysed researches, dedicated to the genome-wide screening of associations of polymorphic genetic locus with psoriasis development. Obtained results allow to reveal pathogenic psoriasis mechanisms, to forecast the character of the clinical course of the disease, as well as the efficiency of therapy and forecast the risk of psoriasis origination at patient’s relatives.