Filaggrin Gene Research Articles

603 AD-DER emollient cream improves hydration and modulates vascularization in atopic dermatitis in vivo

Atopic dermatitis (AD) is a chronic inflammatory disease characterized by a complex interaction between genetic and environmental factors. Defects in cutaneous barrier (filaggrin gene) predispose to the immune-inflammatory condition. Emollients are a standard of care, steroid-sparing, and useful for both prevention and maintenance therapy in AD. AD-DER is an emollient formulated specifically for skin affected by AD, which contains several active agents (liquorice extract, niacinamide, xylitol, laureth-9-polydocanol) to target the underlying AD disease pathophysiology. The aim of the study was to evaluate the efficacy of AD-DER emollient cream in patients with AD by non-invasive techniques. 20 patients aged 18-65, affected by mild to moderate AD at remission, were enrolled in the study. While 10 patients received placebo, the others were treated with AD-DER for two months. Cutaneous hydration was measured by Corneometer (CM825), while Optical Coherence Tomography (OCT) was used to analyse vascularization, thickness and hydration. Corneometer 825 is based on the electric properties of stratum corneum in relation to the water content. OCT allows a cross-sectional imaging of the skin in situ and in real time, with 1-2 mm penetration depth. Corneometer revealed that AD-DER treatment increases hydration in the arms and legs of AD patients (p<0-05, p< 0.01, respectively at 1 and 2 months). OCT showed a significant reduction in hyper-reflectance of stratum corneum (typical of AD) and a modulation of the vascular plexus. All in all, these data support the role of AD-DER cream as an efficacious emollient for AD.

Filaggrin gene loss-of-function mutations constitute a factor in patients with multiple contact allergies.

Polysensitivity is defined as three or more positive patch test reactions. The role of filaggrin gene (FLG) loss-of-function mutations in patients with polysensitivity has not been studied when barrier bypass and possible preceding barrier damage have been excluded. To determine whether FLG loss of function mutations play a role in patients with multiple contact sensitivities when barrier bypass is excluded. One hundred and sixty-nine patients with three or more, non-cross-reacting, positive patch test reactions were prospectively enrolled in this study. Exclusion criteria were a history of hand dermatitis, nickel and metal implants, and stasis dermatitis. Subjects were patch tested with the North American extended patch test series, and with other relevant haptens. DNA was obtained and sequenced for the following FLG loss-of-function mutations: R501X, 2282del4, R2447X, and S3247X. One hundred and sixty-five patients were genotyped for the four FLG mutations. There was a significant association between R501X mutation and polysensitivity. For the other three tested mutations, there were no significant associations with polysensitivity. When all mutations were combined, there was a significant association between loss-of-function FLG mutations and polysensitivity in patients with a history of atopic dermatitis. When skin barrier bypass is excluded, there is a significant association between polysensitivity and FLG loss-of-function mutations.

Ginnalin B induces differentiation markers and modulates the proliferation/differentiation balance via the upregulation of NOTCH1 in human epidermal keratinocytes.

The red maple and sugar maple (Acer rubrum and A. saccharum, respectively) contain acertannins (ginnalins and maplexins), galloylated derivatives of 1,5-anhydro-d-glucitol (1,5-AG, 1). These compounds have a variety of potential medicinal properties and we have shown that some of them promote the expression of ceramide synthase 3. We now report on the beneficial effects of ginnalin B, (6-O-galloyl-1,5-AG, 5), leading to acceleration of skin metabolism and reduction of the turnover time. Ginnalin B dose-dependently increased the relative amount of keratin 10, keratin 1, and filaggrin gene, with maximal increase of 1.7-, 2.9, and 5.2-fold at 100 μM, respectively. The validation study showed that it had superior capacity to induce multiple stages of keratinocyte differentiation and significantly elevated the immunostaining site of keratin 10 and filaggrin in a 3-dimensional cultured human skin model, by 1.2 and 2.8-fold, respectively. Furthermore, ginnalin B caused the arrest of proliferation at the G0/G1 phase but it did not induce apoptotic cell death in normal human keratinocytes. Molecular studies revealed that ginnalin B up-regulated the levels of NOTCH1 and a concomitant increase p21 expression. Ginnalin B, therefore, represents a new class of promising functional and medical cosmetic compound and it could contribute to the maintenance of homeostasis of the epidermis.

Filaggrin gene mutations in hand eczema patients in the Indian subcontinent: A prospective case-control study.

There are no Indian studies on the association between filaggrin gene (FLG) mutations and any dermatosis, including hand eczema. To determine the prevalence of FLG mutations in Indian hand eczema patients, and examine associations between such mutations and any aetiological type of hand eczema. A total of 163 patients and 86 controls were included. Patients were categorized into aetiological subtypes of hand eczema. FLG polymorphisms (S2889X, 2282del4, R501X, and Q2417X) were determined in patients and controls, and correlated with subtypes. The prevalences of FLG mutations were 33.7% in cases and 3.5% in controls. Mutations in S2889X constituted 96.4% of all FLG mutations. No carrier of R501X and Q2417X mutations was identified. Among 55 patients with mutations, irritant contact dermatitis (ICD) with or without atopy was found in 22 patients, allergic contact dermatitis (ACD) with or without atopy was found in 12, and idiopathic hand eczema was found in 12. There was a significant association of FLG mutations with ICD with or without atopy, ACD without atopy, and idiopathic subtypes. FLG mutations were associated with more severe hand eczema. S2889X mutation is commoner in patients than in controls. FLG polymorphisms are associated with specific subtypes of hand eczema and severe disease.

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

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. This cross-sectional, case-control study included children ˂ 6years 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. Of the 57 patients (age range, 2months to 5years; median, 22months), 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 2years. 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 18.3IU/mL, P<0.05). 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.

Association between parental autoimmune disease and atopic dermatitis in their offspring: a matched case-control study.

Atopic dermatitis (AD) is associated with many autoimmune diseases, in part due to overlapping genetic risk loci. While parental atopic disease is an important risk for AD in the offspring, little is known on the putative associations between parental autoimmune disease and AD in their children. All children born between 1996 and 2011 who received a diagnosis of AD in the hospital system before their fifth birthday were matched 1:10 with children from the general population. Maternal and paternal autoimmune diseases were assessed using registry-based data. Conditional logistic regression was performed on the relationships between parental autoimmune diseases and AD in their children. A total of 8589 children with AD were matched with controls. One or more autoimmune disease was identified in 5.89% (506/8589) of mothers to AD children and 3.67% (315/8589) of fathers to AD children compared to 4.85% (4163/85890) and 3.28% (2816/85890) in parents of control children. Maternal autoimmune disease but not paternal autoimmune disease was associated with AD in the offspring (odds ratio [OR] 1.20 [95% confidence interval (CI) 1.20-1.32] and OR 1.08 [0.96-1.22], respectively), Two or more maternal autoimmune diseases, maternal dermatologic autoimmune disease and maternal digestive autoimmune disease were all also associated with AD development in her children (1.96 [95% CI 1.36-2.84], OR 1.60 [95% CI 1.24-2.07] and OR 1.24 [95% CI 1.06-1.45], respectively). The risk of AD is influenced by many factors including atopy status and filaggrin gene mutations. In this matched case-control study, maternal autoimmune disease was associated with AD diagnosis in the offspring. Maternal dermatologic and digestive autoimmune diseases were most closely associated with subsequent AD diagnosis in the offspring.

Whole-exome sequencing in familial keratoconus: the challenges of a genetically complex disorder.

The underlying genetic causes of keratoconus are essentially unknown. Here, we conducted whole-exome sequencing in 2 Brazilian families with keratoconus. Whole-exome sequencing was performed on 6 keratoconus-affected individuals of 2 unrelated pedigrees from Southern Brazil. Pathogenic variants were identified in a modified Trio analysis (1 parent and 2 children) using candidate gene filtering. All the affected subjects underwent detailed corneal tomographic evaluation. Clinically relevant variants that were present in affected individuals at minor allele frequencies <1% were examined in the 1000 Genomes Project single nucleotide polymorphism ABraOM and transcription gene (RefSeq and Ensembl) databases. In family 1, a sequence variant in chromosome 1 (q21.3) was observed within the filaggrin gene. All the tested family members shared a heterozygous missense pathogenic variant in the c.4678C>T position. In family 2, exome analysis demonstrated a sequence variant in chromosome 16 (q24.2) within the gene encoding zinc finger protein 469 (ZNF469). Members of family 2 shared a heterozygous missense variant in the c.1489G>A position. In addition, the exomes of the 2 families were examined for shared genetic variants among all affected individuals. Filtering criteria did not identify any rare sequence variants in a single gene segregated in both families. Our findings show that a complete genotype-phenotype correlation could not be identified, suggesting that keratoconus is a genetically heterogeneous disease. In addition, we believe that whole-exome sequencing-based segregation analysis is probably not the best strategy for identifying variants in families with isolated keratoconus.

Increase in Vitamin D but not Regulatory T Cells following Ultraviolet B Phototherapy of Patients with Atopic Dermatitis.

This study investigated serum 25-hydroxyvitamin D (25(OH)D) concentrations and circulating regulatory T cells in patients with atopic dermatitis receiving narrow-band ultraviolet B (nbUVB) phototherapy. Thirty adult patients with atopic dermatitis were included. Blood samples were collected at baseline and at weeks 2 and 4 of nbUVB phototherapy. Skin biopsies were taken at baseline and at week 4. Serum 25(OH)D concentrations increased significantly following nbUVB phototherapy (estimate of change from baseline to week 2: 32.00 nmol/l, confidence interval (CI) 20.48-43.52, p < 0.0001, n = 25; and from baseline to week 4: 50.30 nmol/l, CI 37.28-63.33, p < 0.0001, n = 18). This increase was independent of the filaggrin gene FLG loss-of-function mutation status. Flow cytometry showed no significant change in regulatory T cells or cytokine profiles of T cells in blood. Real-time quantitative PCR showed no change in skin cytokine levels. In conclusion, nbUVB phototherapy was associated with increased serum 25(OH)D concentrations, but not changes in circulating regulatory T cells in patients with atopic dermatitis.

Mice with epidermal filaggrin deficiency show increased immune reactivity to nickel.

Nickel allergy and dermatitis have been associated with filaggrin gene mutations in epidemiological studies, but the mechanisms mediating these associations are unknown. To investigate whether filaggrin-deficient flaky tail (ft/ft) mice show increased immune reactivity to nickel and elucidate the mechanisms mediating this. The immune responses to nickel, 2,4-dinitrofluorobenzene (DNFB), cinnamal and p-phenylenediamine were assessed in ft/ft and wild-type (WT) mice. The amounts of nickel in the skin of ft/ft and WT mice were determined 20 hours after nickel exposure. The effect of blocking either the interleukin (IL)-17A pathway or the IL-1 pathway on the response to nickel in ft/ft mice was evaluated. Increased responsiveness to nickel, DNFB and cinnamal was observed in ft/ft mice as compared with controls. A reduced amount of nickel was found in the skin of ft/ft mice as compared with WT mice, suggesting increased nickel absorption by the skin of ft/ft mice. Blocking either the IL-17A pathway or the IL-1 pathway reduced nickel responsiveness in ft/ft mice. These findings suggest that the increased nickel responsiveness associated with epidermal filaggrin deficiency is mediated by a combination of increased nickel penetration and the steady-state inflammation found in the skin of filaggrin-deficient mice.

PRIMARY IMMUNE DISEASE MASQUERADING AS SEVERE ATOPIC DERMATITIS

Introduction Netherton syndrome is a primary immune disorder that presents with atopy, diffuse ichthyosis, growth retardation, variable immune defects, and elevated IgE levels. The disease is due to a mutation in the SPINK5 gene, which encodes a serine protease inhibitor, LEKTI, and is inherited in an autosome recessive pattern. We describe a case with features of Netherton syndrome found to have unique mutations in SPINK5 and the filaggrin gene (FLG). Case Description A 4-year-old male with a history of congenital hydrocephalus with meningocele, ADHD, seasonal rhinitis, reactive airway disease and severe eczema presented for eczema management. He has a limited family history of allergic disease. Physical exam documented his height as Discussion This patient presented with clinical features of Netherton syndrome, abnormal NK cells and a FLG mutation. We believe that this is reflective of a novel heterozygous mutation in the SPINK5 gene combined with the reduced expression of filaggrin.

Temporal variation of Staphylococcus aureus clonal complexes in atopic dermatitis: a follow-up study.

A strong link between disease severity and Staphylococcus aureus colonization of the skin has been reported in patients with atopic dermatitis (AD). To examine temporal variations in S. aureus colonization and S. aureus CC type in patients with AD, and to investigate links to disease severity, skin barrier properties and filaggrin gene (FLG) mutations. This was a follow-up study of a cohort of 101 adult patients with AD recruited from an outpatient clinic. Bacterial swabs were taken at baseline and follow-up from lesional skin, nonlesional skin and the nose. Swabs positive for S. aureus were characterized by spa and the respective clonal complex (CC) type was assigned. Patients were characterized with respect to disease severity [Scoring Atopic Dermatitis (SCORAD)], skin barrier properties [transepidermal water loss (TEWL), pH] and FLG mutations. In total, 63 patients participated in a follow-up visit. Twenty-seven patients (43%) were colonized at both visits, 27 were colonized at only one visit and nine (14%) were not colonized at either visit. Of patients colonized at both visits, 52% remained colonized with the same CC type at follow-up. Change in CC type was related to an increase in SCORAD of 10·7 points; patients who carried the same CC type had a reduction in SCORAD of 4·4 points. Significantly higher skin pH was found in patients colonized at both visits, while change in CC type was not related to TEWL, pH or FLG mutations. The data indicate that temporal variation in S. aureus CC type is linked to flares of the disease.

Urinary excretion of phenols, parabens and benzophenones in young men: Associations to reproductive hormones and semen quality are modified by mutations in the Filaggrin gene

BackgroundThe filaggrin gene (FLG) encodes an epidermal protein, filaggrin, which is important for normal skin barrier functions. We previously showed that FLG loss-of-function mutation carriers have a higher internal exposure to some non-persistent chemicals such as certain phthalates and parabens, suggesting increased trans-epidermal penetration. Several groups of non-persistent chemicals are suspected endocrine disrupters with potential to affect testicular function. ObjectivesTo investigate associations between exposure to non-persistent chemicals and testicular function in young Danish men with and without FLG mutations. MethodsWe measured urinary concentrations of bisphenol A (BPA) and other simple phenols, parabens, and UV filters including benzophenones (BP-1, BP-3 and 4-HBP) in men genotyped for FLG R501X, 2282del4, and R2447X loss-of-function mutations; in total 65 mutation carriers and 130 non-carriers (controls) were included. Outcomes were markers of testicular function, assessed by serum reproductive hormones and semen quality. ResultsWe found that associations between urinary chemical concentrations and outcomes were different in cases and controls. Within the group of FLG mutation carriers, higher urinary concentrations of BPA, BP-1 and BP-3 were associated with higher testosterone and estradiol serum levels and lower FSH. Similar trends in hormone levels were observed for FLG mutation carriers with measurable levels of 4-HBP compared to those who had no detectable levels of urinary 4-HBP. Furthermore, those in the highest urinary BPA quartile had lower sperm motility than those in the lower quartiles. None of these associations were evident in the control group. In the control group, however, lower sperm motility and sperm concentration were observed in the men with detectable urinary 4-HBP compared to the men non-detectable urinary 4-HBP. We found no association between any parabens and outcomes, nor for the other measured phenols or UV filters. ConclusionsAssociations between male reproductive health parameters and urinary levels of BPA and benzophenones such as BP-3, BP-1 and 4-HBP were observed in FLG mutation carriers but not in controls from the same study population. This difference between FLG mutation carriers and non-carriers is not explained solely by differences in exposure levels of the examined compounds as e.g. BPA and 4-HBP urinary levels did not differ between the two groups. We hypothesise that effects of exposure to these compounds may be modulated in FLG mutation carriers by either different levels of co-exposures or by route of uptake, with a higher fraction of the uptake by dermal uptake.

Association of filaggrin gene mutations and childhood eczema and wheeze with phthalates and phosphorus flame retardants in house dust: The Hokkaido study on Environment and Children's Health

Background and aimExposure to phthalates and phosphorus flame retardants (PFRs) is considered to be a risk factor for asthma and allergies. However, little is known about the contribution of loss-of-function mutations in the gene encoding filaggrin (FLG) gene, which are considered to be predisposing factors for eczema and asthma, to these associations. We investigated the associations between exposure to phthalates and PFRs in dust and eczema/wheeze among Japanese children, taking into consideration loss-of-function mutations in FLG. MethodsThis study was part of the Hokkaido study on Environment and Children's Health. Seven phthalates and 11 PFRs in household dust were measured by gas chromatography–mass spectrometry. Eczema and wheeze were assessed in children aged 7 years using the International Study of Asthma and Allergies in Childhood questionnaire. Eight FLG mutations previously identified in the Japanese population were extracted from cord blood samples. Children with one or more FLG mutations were considered to be positive for FLG mutations. The study included 296 children who had complete data (birth records, FLG mutations, first trimester and 7 years questionnaires, and phthalate/PFR levels). Odds ratios (ORs) and 95% confidential intervals (CIs) of eczema and wheeze were calculated for log-transformed phthalate/PFR levels by logistic regression. We also performed stratified analyses based on FLG mutations. ResultsThe prevalence rates of eczema and wheeze were 20.6% and 13.9%, respectively. Among children without any FLG mutations, tris (1, 3-dichloro-2-propyl) phosphate (TDCIPP) increased the OR of wheeze, (OR: 1.22, CI: 1.00–1.48). Significant p values for trends were found between tris (2-butoxyethyl) phosphate (TBOEP) and eczema and di-iso-nonyl phthalate (DiNP) and eczema among children without any FLG mutations, respectively. ConclusionsDespite our limited sample size and cross-sectional study design, the effects of indoor environmental factors on childhood eczema and wheeze were clearer in children without loss-of-function mutations in FLG than in children with mutations. Children with FLG mutations might already be cared for differently in terms of medication or parental lifestyle. Further studies in larger populations are warranted so that severity of symptoms and combinations of FLG mutations can be investigated.

Ichthyosis Vulgaris

Ichthyosis Vulgaris

Increased medication costs for filaggrin-related eczema and asthma

Eczema and asthma are common chronic diseases. Eczema affects 15‐20% of schoolchildren and 2‐10% of adults while asthma affects 16‐18% of the UK population. Almost three‐quarters of children with early onset eczema, a severe and persistent form of eczema, will develop asthma in later life. The filaggrin gene helps produce a protein that creates a protective barrier on the skin against the entry of outside substances that trigger allergies. About 1 in 10 people carry a change in the filaggrin gene and this results in the production of defective protein that can no longer help maintain this skin barrier. This UK study aimed to find whether filaggrin mutations were associated with increased prescribing of medication for eczema and asthma and /or an increased number of asthma exacerbations (i.e. worsening) and whether this translated into different healthcare costs. The study shows that children with eczema and asthma carrying this gene change have substantially increased needs for both eczema and asthma medication through most of their childhood. Children with asthma carrying the gene change were also more prone to suffer asthma attacks over a nine‐year period, enhancing both hospital and human costs of the disease. It follows that a simple ‘spit’ gene test, that can be done anytime in life, including at birth or early childhood, could help predict long‐term healthcare costs and the long‐term risk of more severe disease for individuals with common chronic conditions such as eczema and asthma. Children and adults with filaggrin gene mutations may benefit from targeted treatment regimes, such as daily use of emollients from birth, which could lead to cost savings for healthcare systems and improvements in disease control and quality‐of‐life.

Induced pluripotent stem cell line from an atopic dermatitis patient heterozygous for c.2282del4 mutation in filaggrin: KCLi001-A

We have generated an induced pluripotent stem cell (iPSC) line KCLi001-A (iOP118) from a female atopic dermatitis (AD) patient, heterozygous for the loss-of-function mutation c.2282del4 in the filaggrin gene (FLG). Epidermal keratinocytes were reprogrammed using non-integrating Sendai virus vectors. The entire process of derivation and expansion of AD-iPSCs were performed under xeno-free culture conditions. Characterization of KCLi001-A line included molecular karyotyping, mutation screening using restriction enzyme digestion and Sanger sequencing, while pluripotency and differentiation potential were confirmed by expression of associated markers in vitro and by in vivo teratoma assay.

β-1,3/1,4-Glucan Lichenan from Cetraria islandica (L.) ACH. induces cellular differentiation of human keratinocytes

Lichenan (molecular weight 275 kDa, β-D-1,3/1,4-glucopyranose ratio 1:3) from Cetraria islandica at a concentration of 100 μg/mL induced terminal cellular differentiation of primary human keratinocytes as demonstrated by immunofluorescence staining using cytokeratin 10 and involucrin as marker proteins. Lichenan-derived oligosaccharides (DP3 to 8), obtained by acid-catalyzed partial hydrolysis of the polymer, did not influence cellular differentiation. Cytokeratin, filaggrin, involucrin, loricrin and transglutaminase gene expression as typical differentiation markers was increased by lichenan in a time-dependent manner. Lichenan upregulated gene cluster which were mostly related to cellular differentiation with focus on MAPK signaling as was shown by Whole Human Genome Microarray. These gene expression data from the array experiments were subsequently confirmed by qPCR for selected genes. For identification of the molecular binding structures of lichenan 1- and 2-D PAGE of keratinocyte protein membrane preparations was performed, followed by blotting with FITC-labeled lichenan and subsequent mass spectrometric identification of the pinpointed proteins. Epidermal growth factor receptor (EGFR) and integrin β4, both proteins being strongly involved in induction of keratinocyte differentiation were identified. In addition, protein disulfide isomerase A3 (PDIA3) showed strong binding to FITC-lichenan, indicating this enzyme to be an intracellular target of the glucan for induction of the cellular differentiation of keratinocytes. As lichenan did not influence the EGFR phosphorylation and the phosphorylation of CREB transcription factor but strongly interacted with cytosolic proteins it is hypothized that the glucan may interact with EGFR and is subsequently internalized into the cell via endosomal uptake, interacting with PDIA3, which again alters TGFβ1 signaling towards keratinocyte differentiation.

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

BackgroundX-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 presentationWe 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.ConclusionsIn 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.

Tiled array-based sequencing identifies enrichment of loss-of-function variants in the highly homologous filaggrin gene in African-American children with severe atopic dermatitis.

Filaggrin (FLG) loss-of-function (LOF) variants are a major risk factor for the common inflammatory skin disease, atopic dermatitis (AD) and are often population-specific. African-American (AA) children are disproportionately affected with AD, often later developing asthma and/or allergic rhinitis and comprise an atopy health disparity group for which the role of FLG LOF is not well known. Discovery of FLG LOF using exome sequencing is challenging given the known difficulties for accurate short-read alignment to FLG's high homology repeat variation. Here, we employed an array-based sequencing approach to tile across each FLG repeat and discover FLG LOF in a well-characterized cohort of AA children with moderate-to-severe AD. Five FLG LOF were identified in 23% of our cohort. Two novel FLG LOF singletons, c.488delG and p.S3101*, were discovered as well as p.R501*, p.R826* and p.S3316* previously reported for AD. p.S3316* (rs149484917) is likely an African ancestral FLG LOF, reported in African individuals in ExAC (Exome Aggregation Consortium), Exome Variant Server (ESP), and 4 African 1000G population databases (ESN, MSL, ASW, and ACB). The proportion of FLG LOF (11.5%) among the total FLG alleles in our cohort was significantly higher in comparisons with FLG LOF reported for African individuals in ExAC (2.5%; P=4.3×10-4 ) and ESP (1.7%; P=3.5×10-5 ) suggesting a disease-enrichment effect for FLG LOF. Our results demonstrate the utility of array-based sequencing in discovering FLG LOF, including novel and population-specific, which are of higher prevalence in our AA severe AD group than previously reported.

Effect of atopic skin stressors on natural moisturizing factors and cytokines in healthy adult epidermis.

Epidermal deficiency of filaggrin, and the derived natural moisturizing factors (NMFs), is associated with increased risk of atopic dermatitis (AD). While filaggrin gene mutations cause filaggrin deficiency, there is limited insight into the causative environmental factors. To explore the effect of selected exogenous skin stressors on NMF and skin cytokine levels in healthy adult epidermis. Forty healthy volunteers (aged 18-49 years) were exposed to hard, soft and chlorinated water, 0·5% sodium lauryl sulfate, house dust mite, cat allergen, staphylococcal enterotoxin B (SEB), cooling and histamine. Participants were tape-stripped and biophysiological measurements performed. NMF was determined after 24 and 48 h, whereas skin cytokines were measured after 24 h for selected exposures. At 24 h, a significant decrease in NMFs was observed for soft (0·51 ± 0·19 g m-2 h-1 ) and hard water (0·61 ± 0·32 g m-2 h-1 ) compared with occlusion alone (0·71 ± 0·18 g m-2 h-1 ). Hard water led to increased levels of interleukin (IL)-4, interferon (IFN)-γ and IL-10. Exposure to house dust mite and SEB led to a significant decrease in NMFs after 24 h (0·77 ± 0·28 and 0·80 ± 0·28 g m-2 h-1 , respectively) compared with occlusion alone (1·00 ± 0·42 g m-2 h-1 ). House dust mite led to an increase in IFN-γ, IL-2 and IL-4 vs. the nonoccluded control site. Based on experimental exposure to selected atopic skin stressors, we conclude that NMFs levels are decreased along with increased secretion of various skin cytokines in healthy individuals. Our data highlight environmental factors that might play a role in AD pathophysiology.