Filaggrin gene variants among Saudi patients with ichthyosis vulgaris.

Ichthyoses are a heterogeneous group of cornification disorders. The most common form of ichthyoses is ichthyosis vulgaris (IV) ([OMIM] #146,700), which can be inherited as autosomal semi-dominant mutation in the filaggrin gene (FLG). We present the findings of a study involving 35 Saudi patients with a clinical diagnosis of ichthyosis vulgaris. For identifying the pathogenic mutation of their disease, we used Sanger sequencing analysis of the extracted DNA samples. We also identified the underlying 22 FLG variants, which have been seen before. However, the detected mutations do not involve the common p.R501* c. 2282del4 mutations reported in European populations. Indeed, we did not identify any statistical influence of the homozygous or heterozygous genotypes on the phenotype severity of the disease.

Revisiting the Roles of Filaggrin in Atopic Dermatitis.

The discovery in 2006 that loss-of-function mutations in the filaggrin gene (FLG) cause ichthyosis vulgaris and can predispose to atopic dermatitis (AD) galvanized the dermatology research community and shed new light on a skin protein that was first identified in 1981. However, although outstanding work has uncovered several key functions of filaggrin in epidermal homeostasis, a comprehensive understanding of how filaggrin deficiency contributes to AD is still incomplete, including details of the upstream factors that lead to the reduced amounts of filaggrin, regardless of genotype. In this review, we re-evaluate data focusing on the roles of filaggrin in the epidermis, as well as in AD. Filaggrin is important for alignment of keratin intermediate filaments, control of keratinocyte shape, and maintenance of epidermal texture via production of water-retaining molecules. Moreover, filaggrin deficiency leads to cellular abnormalities in keratinocytes and induces subtle epidermal barrier impairment that is sufficient enough to facilitate the ingress of certain exogenous molecules into the epidermis. However, although FLG null mutations regulate skin moisture in non-lesional AD skin, filaggrin deficiency per se does not lead to the neutralization of skin surface pH or to excessive transepidermal water loss in atopic skin. Separating facts from chaff regarding the functions of filaggrin in the epidermis is necessary for the design efficacious therapies to treat dry and atopic skin.

Mood symptoms, neurodevelopmental traits, and their contributory factors in X-linked ichthyosis, ichthyosis vulgaris and psoriasis.

BACKGROUND: High rates of adverse mood/neurodevelopmental traits are seen in multiple dermatological conditions, and can significantly affect patient quality of life. Understanding the sex-specific nature, magnitude, impact and basis of such traits in lesser-studied conditions like ichthyosis, is important for developing effective interventions. AIM: To quantify and compare relevant psychological traits in men with X-linked ichthyosis (XLI, n = 54) or in XLI carrier women (n = 83) and in patients with ichthyosis vulgaris (IV, men n = 23, women n = 59) or psoriasis (men n = 30, women n = 122), and to identify factors self-reported to contribute most towards depressive, anxious and irritable phenotypes. METHODS: Participants recruited via relevant charities or social media completed an online survey of established questionnaires. Data were analysed by sex and skin condition, and compared with general population data. RESULTS: Compared with the general population, there was a higher rate of lifetime prevalence of mood disorder diagnoses across all groups and of neurodevelopmental disorder diagnoses in the XLI groups. The groups exhibited similarly significant elevations in recent mood symptoms (Cohen d statistic 0.95-1.28, P < 0.001) and neurodevelopmental traits (d = 0.31-0.91, P < 0.05) compared with general population controls, and self-reported moderate effects on quality of life and stigmatization. There were strong positive associations between neurodevelopmental traits and recent mood symptoms (r > 0.47, P < 0.01), and between feelings of stigmatization and quality of life, particularly in men. Numerous factors were identified as contributing significantly to mood symptoms in a condition or sex-specific, or condition or sex-independent, manner. CONCLUSION: We found that individuals with XLI, IV or psoriasis show higher levels of mood disorder diagnoses and symptoms than matched general population controls, and that the prevalence and severity of these is similar across conditions. We also identified a number of factors potentially conferring either general or condition-specific risk of adverse mood symptoms in the three skin conditions, which could be targeted clinically and/or through education programmes. In clinical practice, recognizing mood/neurodevelopmental problems in ichthyosis and psoriasis, and addressing the predisposing factors identified by this study should benefit the mental health of affected individuals.

Low Threshold for Cutaneous Allergen Sensitization but No Spontaneous Dermatitis or Atopy in FLG-Deficient Mice.

Loss of FLG causes ichthyosis vulgaris. Reduced FLG expression compromises epidermal barrier function and is associated with atopic dermatitis, allergy, and asthma. The flaky tail mouse harbors two mutations that affect the skin barrier, Flgft, resulting in hypomorphic FLG expression, and Tmem79ma, inactivating TMEM79. Mice defective only for TMEM79 featured dermatitis and systemic atopy, but also Flgft/ft BALB/c congenic mice developed eczema, high IgE, and spontaneous asthma, suggesting that FLG protects from atopy. In contrast, a targeted Flg-knockout mutation backcrossed to BALB/c did not result in dermatitis or atopy. To resolve this discrepancy, we generated FLG-deficient mice on pure BALB/c background by inactivating Flg in BALB/c embryos. These mice feature an ichthyosis phenotype, barrier defect, and facilitated percutaneous sensitization. However, they do not develop dermatitis or atopy. Whole-genome sequencing of the atopic Flgft BALB/c congenics revealed that they were homozygous for the atopy-causing Tmem79matted mutation. In summary, we show that FLG deficiency does not cause atopy in mice, in line with lack of atopic disease in a fraction of patients with ichthyosis vulgaris carrying two Flg null alleles. However, the absence of FLG likely promotes and modulates dermatitis caused by other genetic barrier defects.

Filaggrin expression via immunohistochemistry in basal cell carcinoma and squamous cell carcinoma.

BACKGROUND: Filaggrin is a protein integral to the structure and function of the epidermis. Filaggrin (FLG) loss-of-function (LOF) mutations are common and increase the risk of developing atopic dermatitis (AD) and ichthyosis vulgaris (IV). Epidemiologic data suggest a link between skin cancer and AD. We examined if FLG staining pattern can be used to characterize cutaneous squamous cell carcinomas (SCC), basal cell carcinomas (BCC), and reactive squamous epithelium. METHODS: Tissue microarrays (TMAs) were created from 196 cases of formalin-fixed paraffin-embedded (FFPE) SCC and 144 BCC cases. TMAs and sections of reactive squamous epithelium were stained with optimized anti-FLG antibody and evaluated for FLG expression (normal, abnormal, or negative). RESULTS: FLG was absent in poorly differentiated (PD) compared to well-differentiated (WD) SCC (P < .0001) and moderately-differentiated (MD) (P = .0231) SCC, and in MD compared to WD SCC (P = .0099). Abnormal staining was significantly increased in PD compared to WD cases (P = .0039) and in MD compared to WD cases (P = .0006). Most BCC did not exhibit FLG expression (P < .05). Reactive squamous epithelium demonstrated normal, but exaggerated FLG expression. CONCLUSIONS: Our findings demonstrate the differences in FLG expression patterns in types of keratinocyte carcinomas and their mimickers.

Genetics of Inherited Ichthyoses and Related Diseases.

Inherited ichthyoses are classified as Mendelian disorders of cornification (MEDOC), which are defined on the basis of clinical and genetic features and are mainly divided into non-syndromic and syndromic ichthyoses. Numerous genes, which encode for corresponding proteins, are involved in the normal differentiation of keratinocytes (cornification) and participate in the formation of a functional epidermal barrier. To date, mutations in more than 50 genes are known to result in various types of ichthyoses. Thanks to modern genetic diagnostic methods based on targeted next generation sequencing (NGS), approximately 80-90% of cases can be resolved at present. Further sequencing methods covering the whole exome (WES) or whole genome (WGS) will obviously elucidate another portion of the remaining unknown ichthyoses in the future.

Palmar hyperlinearity in early childhood atopic dermatitis is associated with filaggrin mutation and sensitization to egg.

BACKGROUND/OBJECTIVES: Palmar hyperlinearity is a typical clinical feature of Filaggrin gene (FLG) null mutations. There are reports of FLG mutations and allergic sensitization; however, reports on the relationship between palmar hyperlinearity to sensitization are limited. This study aimed to examine the association between palmar hyperlinearity and sensitization in atopic dermatitis (AD) children. METHODS: This cross-sectional, case-control study included children ˂ 6 years old with moderate-severe AD whose parents consented for mutation analysis and photographic documentation. Each child underwent genotyping to detect the eight most prevalent FLG mutations in the Japanese population: R501X, 3321delA, S1695X, Q1701X, S2554X, S2889X, S3296X, and K4022X. Clinical features and parameters including egg-specific IgE were examined, and palm photographs were evaluated by 12 trained dermatologists blinded to genotyping results. RESULTS: Of the 57 patients (age range, 2 months to 5 years; median, 22 months), 16 were heterozygotes and three were compound heterozygotes. Palmar hyperlinearity, as recognized by more than two-thirds of dermatologists, was significantly associated with FLG mutation (P = 0.002, OR = 6.98, 95% CI = 2.1-23.7), and this association was observed especially in children over 2 years. Cross-shaped crease of the thenar eminence, as known in previous reports, also demonstrated significant correlation with FLG mutation. When the children were divided according to the presence or absence of palmar hyperlinearity, the egg white-specific IgE was significantly higher in the hyperlinearity group (55.9 vs 18.3 IU/mL, P < 0.05). CONCLUSIONS: Palmar hyperlinearity indicates possible inherited barrier abnormalities of the skin in early childhood. Its identification may help to predict a more accurate prognosis, such as sensitization.

X-linked and autosomal dominant forms of the ichthyosis in coinheritance.

According to modern classification, there are two forms of inherited ichthyoses: syndromic and non-syndromic, each of them consists of more than ten different nosologies. The commonest types of the ichthyosis are X-linked recessive (prevalence 1/2000-6000 in men) and autosomal dominant, or ichthyosis vulgaris with incomplete penetrance (1/250-1000). The X-linked form is associated with mutations in steroid sulfatase STS gene, it is noteworthy that there is a full deletion of the gene in 90% of cases. Ichthyosis vulgaris is caused by heterozygous mutations in the FLG gene encoding filaggrin. It is important to note that the clinical forms of these diseases are indistinguishable. The aim of this study was to search for pathogenic or likely pathogenic mutations which are associated with various forms of the inherited ichthyosis such as other inherited diseases with similar phenotypic signs. The sequencing was done on a HiSeq 4000 sequencer (Illumina) by paired-end reading (2 × 150 bp). The identified mutation p.Arg2037Ter in the heterozygous condition has been described before in databases as being pathogenic. Also, our patient has a full deletion of the STS gene and it was found that our patient carries two pathogenic mutations which are related to different forms of the inherited ichthyosis.

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.

Filaggrin gene polymorphisms in Iranian ichthyosis vulgaris and atopic dermatitis patients.

BACKGROUND: Filaggrin is a key structural epidermal protein in terminal differentiation and formation of skin barrier. The important role of filaggrin and its effects in various cutaneous and noncutaneous disorders initiated a cascade of considerable research in recent years. Loss-of-function mutations in FLG, the human gene encoding profilaggrin/filaggrin, is the cause of the common skin condition ichthyosis vulgaris (IV) and major genetic predisposing factor for atopic dermatitis (AD). Several null mutations in the FLG gene that lead to a decrease or absence of filaggrin in skin and predispose these conditions have been described. OBJECTIVE: The aim of this study was to investigative genetic polymorphism of FLG in Iranian patients with IV and AD. METHODS: In the current study, we carried out full sequencing of the entire FLG coding region in 30 IV patients and 30 AD patients, and also 60 healthy controls. RESULTS: In our research, we identified 43 variants reported previously and two novel variants. CONCLUSION: In our study, in the AD and IV patients, loss-of-function FLG mutation was not found. This means that another mechanism other than FLG nonsense mutation is involved in the pathogenesis of these patients.

Exacerbation of ichthyosis vulgaris phenotype by co-inheritance of STS and FLG mutations in a Chinese family with ichthyosis: a case report.

BACKGROUND: X-linked ichthyosis (XLI) is a recessive keratinization condition caused by deficient activity of steroid-sulfatase due to mutations in steroid sulfatase (STS) gene located on the X chromosome. In contrast, ichthyosis vulgaris (IV) is caused by filaggrin deficiency due to semi-dominant loss-of-function mutations of filaggrin (FLG) gene. Filaggrin defects could synergize with XLI to exacerbate its phenotype. CASE PRESENTATION: We report a Chinese family with patients presenting diverse phenotype of Keratosis pilaris. A next-generation sequencing panel interrogating 25 ichthyosis related genes with sequencing coverage of the coding regions and splice site junctions, was applied to screen genetic mutations. A gross deletion encompassing the STS gene ranging from exon 1-10 and the FLG c.3321delA mutation were identified in a 31-year old male proband, one of his sister, and his mother, and all the three patients showed obvious symptom. The deletion of STS gene was confirmed by real-time quantitative PCR. The proband's another sister and his two nephews carried only FLG c.3321delA mutation. Patients carried both mutations presented more severe symptom, while those only carried FLG c.3321delA mutation showed slight or normal phenotype. CONCLUSIONS: In conclusion, we found that the IV phenotype was exacerbated by co-inheritance of STS and FLG mutations in a Chinese family with ichthyosis. Other genomic regions no included in the study might be also involved in phenotypic modifications.

Enhanced Expression of Genes Related to Xenobiotic Metabolism in the Skin of Patients with Atopic Dermatitis but Not with Ichthyosis Vulgaris.

Previous transcriptome analyses underscored the importance of immunological and skin barrier abnormalities in atopic dermatitis (AD). We sought to identify pathogenic pathways involved in AD by comparing the transcriptomes of AD patients stratified for filaggrin (FLG)-null mutations to those of both healthy donors and patients with ichthyosis vulgaris. We applied RNA sequencing to analyze the whole transcriptome of nonlesional skin. We found that 607 genes (476 up-regulated and 131 down-regulated by >2-fold) and 193 genes (172 up-regulated and 21 down-regulated by >2-fold) were differentially expressed when all AD or ichthyosis vulgaris patients were compared with healthy donors, respectively. Expression of genes involved in RNA/protein turnover and adenosine triphosphate synthesis, as well as genes involved in cell death, response to oxidative stress, DNA damage/repair, and autophagy, were significantly enriched in AD skin and, to a lesser extent, in ichthyosis vulgaris skin. FLG-null mutations appear to hardly interfere with current observations. Genes related to xenobiotic metabolism were up-regulated in AD skin only, as were genes related to arachidonic, linoleic, and α-linolenic acid metabolism. Thus, this work newly links AD pathogenesis to aberrant expression of genes related to xenobiotic metabolism.

Sequence variants in nine different genes underlying rare skin disorders in 10 consanguineous families.

BACKGROUND: Genodermatoses represent genetic anomalies of skin tissues including hair follicles, sebaceous glands, eccrine glands, nails, and teeth. Ten consanguineous families segregating various genodermatosis phenotypes were investigated in the present study. METHODS: Homozygosity mapping, exome, and Sanger sequencing were employed to search for the disease-causing variants in the 10 families. RESULTS: Exome sequencing identified seven homozygous sequence variants in different families, including: c.27delT in FERMT1; c.836delA in ABHD5; c.2453C>T in ERCC5; c.5314C>T in COL7A1; c.1630C>T in ALOXE3; c.502C>T in PPOX; and c.10G>T in ALDH3A2. Sanger sequencing revealed three homozygous variants: c.1718 + 2A>G in FERMT1; c.10459A>T in FLG; and c.92delT in the KRT14 genes as the underlying genetic cause of skin phenotypes. CONCLUSION: This study supports the use of exome sequencing as a powerful, efficient tool for identifying genes that underlie rare monogenic skin disorders.

Treatment of ichthyosis vulgaris with a urea-based emulsion: videodermatoscopy and confocal microscopy evaluation.

BACKGROUND: Ichthyosis vulgaris is a common disorder of keratinization caused by mutations in the filaggrin gene and clinically characterized by variable degree of xerosis. METHODS: Five patients affected by ichthyosis vulgaris and moderate to severe xerosis of the lower limbs, were treated twice daily for 30 days with an emulsion containing 10% urea, ceramides, and natural moisturizing factors (NMF). Evaluation was performed at baseline and at the end of treatment by clinical examination, Visual Analogue Scale to quantify itch, videodermatoscopy (VD), and reflectance confocal microscopy (RCM). Patients were also asked to provide an acceptability rating of the product based on spreadability, absorbency, odor, pleasantness and ease of application. RESULTS: At the end of treatment the tested urea-based emulsion resulted in a significant clinical improvement of xerosis in all patients. The product determined a remarkable reduction of itch, it was well tolerated and it had a good cosmetic acceptability. VD and RCM objectively confirmed the reduction/disappearance of scales and the improvement/normalization of furrow's size and morphology. CONCLUSIONS: The tested urea-based emulsion represents a valid option for the treatment of xerosis in patients affected by ichthyosis vulgaris. VD and RCM confirmed to be useful non-invasive techniques for the therapeutic monitoring of this condition.

Concurrent Chondrodysplasia Punctata Type 2 (Conradi-Hunermann-Happle Syndrome) and Ichthyosis Vulgaris in Teenaged Twin Girls.

We present concurrent X-linked chondrodysplasia punctata and ichthyosis vulgaris in adolescent fraternal twin girls, notable for initial presentation with dry skin in adolescence, characterized by dark-brown scale typical of ichthyosis vulgaris and blaschkolinear, atrophic, scaly plaques. This constellation of findings prompted further genetic investigation. Using a multigene approach to examine 39 genes associated with congenital ichthyosis, next-generation sequencing revealed a novel heterozygous missense mutation at a mutational hotspot in the EBP gene c.439C>T (p.R147C) in conjunction with a single nonsense mutation in the FLG gene (p.R501X) in both sisters. These individuals highlight the clinical variability of Conradi-Hunermann-Happle syndrome, illustrate the possibility of co-occurrence of rare and common forms of ichthyosis, and demonstrate the utility of multigene analysis.

[ANALYSIS OF ONE-CARBON METABOLISM GENES AND EPIDERMAL DIFFERENTIATION COMPLEX IN PATIENTS WITH ICHTHYOSIS VULGARIS].

The aim of the study was to evaluate the effects of allelic polymorphism of the FLG and MTHFR genes and their associations in gynecological patients with ichthyosis vulgaris. Gynecological disorders are observed in presence of some forms of ichtyosis. From the prospective of improving nation's healthcare, the greatest attention is drawn to reproductive disorders. Based on this, the research was also tasked with studying of the genetic nature of gynecological diseases, as well as the influence of geographical latitude on the frequencies of mutagenic alleles of the FLG gene and heterogeneous carriers of these mutations. The collection of clinical-gynecological history was carried out by the method of single registration of the proband on the basis of the Regional Clinical Dermatological and Venereological Health Center No. 1 and the Dermatovenerological Health Centers of the Kharkiv Region. The diagnosis and form of dermatosis is established on the basis of the analysis of clinical and gynecological data and the results of laboratory tests in accordance with ICD-10: ichthyosis vulgaris (Q 80.1.0, OMIM 146700). The data on 18 women and 20 men from 3 families, aged 26 to 76 years old, suffering from ichthyosis, were analyzed. As a result of the study, a direct correlation was determined between the latitude and frequencies of mutant alleles of the FLG gene, as well as between the geographical latitude and frequency of heterozygous carriers of these mutations. The frequencies of the T allele and the CT genotype according to polymorphic variant C677T of the MTHFR gene demonstrate feedback with the latitude indicators. The frequency distributions of the 2282del4 allele and the CT genotype, the N/2282del4 and CT genotypes, the 2282del4 and T alleles, the N/2282del4 genotype and the T allele have opposite latitudinal zonation. The established connections made it possible to predict the development of gynecological pathologies in women with ichthyosis vulgaris. The prevalence of endometriosis and endometrial cancer in women with ichthyosis vulgaris in the Kharkiv region was 33.3%, while the average for the female population in the region was 0.29-0.35%. The number of children born to women with ichthyosis vulgaris did not differ from the regional index.