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Per- and polyfluoroalkyl substances (PFAS) are a class of highly stable chemicals, widely used in everyday products, and widespread in the environment, even in pregnant women. While epidemiological studies have linked prenatal exposure to PFAS with atopic dermatitis in children, little is known about their toxic effects on skin development, especially during the embryonic stage. In this study, we utilized human embryonic stem cells to generate non-neural ectoderm (NNE) cells and exposed them to six PFAS (perfluorooctanoic acid (PFOA), undecafluorohexanoic acid (PFHxA), heptafluorobutyric acid (PFBA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluorobutyric acid (PFBS)) during the differentiation process to assess their toxicity to early skin development. Our results showed that PFOS altered the spindle-like morphology of NNE cells to a pebble-like morphology, and disrupted several NNE markers, including KRT16, SMYD1, and WISP1. The six PFAS had a high potential to cause hypohidrotic ectodermal dysplasia (HED) by disrupting the expression levels of HED-relevant genes. Transcriptomic analysis revealed that PFOS treatment produced the highest number (1156) of differentially expressed genes (DEGs) among the six PFAS, including the keratinocyte-related genes KRT6A, KRT17, KRT18, KRT24, KRT40, and KRT81. Additionally, we found that PFOS treatment disturbed several signaling pathways that are involved in regulating skin cell fate decisions and differentiation, including TGF-β, NOTCH, Hedgehog, and Hippo signaling pathways. Interestingly, we discovered that PFOS inhibited, by partially interfering with the expression of cytoskeleton-related genes, the ciliogenesis of NNE cells, which is crucial for the intercellular transduction of the above-mentioned signaling pathways. Overall, our study suggests that PFAS can inhibit ciliogenesis and hamper the transduction of important signaling pathways, leading potential congenital skin diseases. It sheds light on the underlying mechanisms of early embryonic skin developmental toxicity and provides an explanation for the epidemiological data on PFAS. ENVIRONMENTAL IMPLICATION: We employed a model based on human embryonic stem cells to demonstrate that PFOS has the potential to elevate the risk of hypohidrotic ectodermal dysplasia. This is achieved by targeting cilia, inhibiting ciliogenesis, and subsequently disrupting crucial signaling pathways like TGF-β, NOTCH, Hedgehog, and Hippo, during the early phases of embryonic skin development. Our study highlights the dangers and potential impacts of six PFAS pollutants on human skin development. Additionally, we emphasize the importance of closely considering PFHxA, PFBA, PFHxS, and PFBS, as they have shown the capacity to modify gene expression levels, albeit to a lesser degree., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Genodermatoses are rare heterogeneous genetic skin diseases with multiorgan involvement. They severely impair an individual's well-being and can also lead to early death., Methods: During the progress of this review, we have implemented a targeted research approach, diligently choosing the most relevant and exemplary articles within the subject matter. Our method entailed a systematic exploration of the scientific literature to ensure a compre-hensive and accurate compilation of the available sources., Results: Among genodermatoses, X-linked ones are of particular importance and should always be considered when pediatric males are affected. Regardless of other syndromic forms without prevalence of skin symptoms, X-linked genodermatoses can be classified in three main groups: keratinization defects, pigmentation defects, and inflammatory skin diseases. Typical examples are dyskeratosis congenita, keratosis follicularis spinulosa decalvans, hypohidrotic ectodermal dysplasia, chondrodysplasia punctata, hypohidrotic ectodermal dysplasia, incontinentia pigmenti, chronic granulomatous disease, CHILD syndrome and ichthyosis. In this field, genetic diagnosis of the specific disease is important, also considering that numerous clinical trials of orphan drugs and genetic therapies are being proposed for these rare genetic diseases., Conclusions: Thus, this chapter starts from clinical to molecular testing and ends with a review of all clinical trials on orphan drugs and gene therapy for genodermatoses.

Hypohidrotic/anhidrotic ectodermal dysplasia (H/AED) is a rare congenital disorder that involves the epidermis and one or more of its appendages. Atopic dermatitis (AD)-like eczema in H/AED has been reported by several authors. In this study, a 13-year-old Korean boy presented to the Department of Dermatology of Korean Medicine with persistent, pruritic, AD-like eczema throughout the body. The eczema had persisted from early childhood (1 year-of-age), and the boy had occasionally been prescribed topical steroids and anti-pruritic agents. Before his visit, the patient's skin lesions had deteriorated and he had considered using alternative medicine. The patient was hospitalized for 5 days; during which time he was treated using twice-a-day acupuncture Moreover, we prescribed the patient modified Danguieumja on the basis of his blood-heat and wind-dryness patterns. To assess the efficacy of the treatments, the severity of symptom was evaluated using the Scoring of Atopic Dermatitis (SCORAD) index. Treatment safety was also assessed by laboratory tests on the admission and discharge days. The results showed that the patient' SCORAD scores decreased continuously. The total SCORAD scores were 68.5, 38.2, and 38.1 on admission, discharge, and follow up visit day respectively. Subjective symptoms and pruritus had also subsided. There were no reported adverse events during hospitalization, or abnormalities observed on AST, ALT, BUN and creatinine testing. It seems acupuncture and herbs may serve as an alternative for H/AED patients, however, we must concede that no direct evidence is available at present to explain the efficacy of the acupuncture and herbs. [ABSTRACT FROM AUTHOR]

A síndrome de Christ-Siemens-Touraine (displasia ectodérmica hipoidrótica) é uma síndrome rara, caracterizada pela tríade de sudorese reduzida ou ausente, hipotricose e dentição defeituosa. Bossas frontais proeminentes, nariz em sela, lábio inferior espesso e queixo pontudo fazem com que os pacientes tenham uma fácies característica e semelhante. A síndrome completa ocorre em homens, visto tratar-se de herança recessiva ligada ao X.Christ-Siemens-Touraine syndrome (hypohidrotic ectodermal dysplasia) is a rare syndrome characterized by the triad of absent or reduced sweating, hypotrichosis, and defective dentition. The prominent forehead, saddle nose, thick lower lip and pointy chin produce a distinctive facies. The full syndrome only occurs in men as it is an X-linked recessive condition.

Objective: The objective of this systematic review was to determine the orthodontic and dentofacial orthopedic treatments carried out in patients with ectodermal dysplasia to facilitate functional and aesthetic rehabilitation., Methods: The systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement. We systematically searched PubMed, Web of Science, Scopus, Scielo, LILACS, EBSCOhost and Embase databases up to 6 January 2022. We included articles describing patients with any type of ectodermal dysplasia who received orthodontic or dentofacial orthopedic treatment to facilitate functional and aesthetic oral rehabilitation. The search was not restricted by language or year of publication. The quality of the studies was assessed using the Joanna Briggs Institute Quality Assessment Scale of the University of Adelaide for case series and case reports. The review was registered at the University of York Centre for reviews (CRD42021288030)., Results: Of the initial 403 studies found, 29 met the inclusion criteria. After applying the quality scale, 23 were left for review-21 case reports and 2 case series. The initial age of patients ranged from 34 months to 24 years. Thirteen studies were on hypohidrotic and/or anhidrotic ectodermal dysplasia, of which two were X-chromosome linked. In one study, the patient had Wiktop syndrome, and in nine the type of ectodermal dysplasia was not specified. The duration of treatment was 7 weeks to 10 years. The treatments described were: fixed orthodontic appliances or simple acrylic plates designed for tooth movement, including leveling and aligning, closing of diastemata, retraction of impacted teeth in the dental arch; clear aligners; fixed and/or removable appliances for the correction of skeletal and/or dentoalveolar relationships; palatal expanders in combination with face masks for orthopedic traction of the maxilla; and orthognathic surgery. Only three studies provided cephalometric data., Conclusion: The level of evidence of the articles reviewed was low and most orthopedic and dentofacial orthodontic treatments described were focused on correcting dental malpositioning and jaw asymmetries and not on stimulating growth from an early age. Studies with greater scientific evidence are needed to determine the best treatment for these patients., (© 2022. The Author(s).)

Pathogenic variants of the gene Eda cause X-linked hypohidrotic ectodermal dysplasia (XLHED), which is characterized by structural abnormalities or lack of ectodermal appendages. Signs of dysplasia are not restricted to derivatives of the ectodermal layer, but mesodermal abnormalities, such as craniofacial dysmorphism, are also frequently observed, suggesting close reciprocal interactions between the ectoderm and mesoderm; however, a causal link has remained unsubstantiated. We investigated the functional impact of defective ectodysplasin A1 (Eda1) signaling on postnatal bone homeostasis in Eda1-deficient Tabby mice. Interestingly, Eda1 was detected in wild-type mouse calvariae throughout postnatal lifetime. In calvariae, bone-lining Osterix (Osx)+ osteoblasts stained positive for Eda1, and osteoclasts were revealed as Eda receptor (Edar)-positive. Moreover, adult Eda1-deficient calvarial bone showed osteopetrosis-like changes with significantly diminished marrow space, which was maintained during adulthood. Concomitantly with osteopetrosis-like changes, Tabby calvarial bone and Tabby bone marrow-derived osteoclasts had far less osteoclastic activity-associated co-enzymes including cathepsin K, Mmp9, Trap, and Tcirg1 (V-type proton ATPase a3 subunit) compared with wild-type calvariae in vivo or osteoclasts in vitro, indicating that Eda1 deficiency may affect the activity of osteoclasts. Finally, we confirmed that nuclear Nfatc1-positive osteoclasts were strongly diminished during mature osteoclastic differentiation under M-CSF and RANKL in the Tabby model, while Fc-EDA treatment of Tabby-derived osteoclasts significantly increased nuclear translocation of Nfatc1. Furthermore, we identified enhanced Nfatc1 and NF-κB transcriptional activity following Fc-EDA treatment in vitro using luciferase assays. Overall, the results indicate that diminished expressions of osteoclastic activity-associated co-enzymes may lead to disturbed bone homeostasis in Tabby calvariae postnatally.

Ectodysplasin A (EDA) signaling is initially identified as morphogenic signaling regulating the formation of skin appendages including teeth, hair follicles, exocrine glands in mammals, feathers in birds and scales in fish. Gene mutation in EDA signaling causes hypohidrotic ectodermal dysplasia (HED), a congenital hereditary disease with malformation of skin appendages. Interestingly, emerging evidence suggests that EDA and its receptors can modulate the proliferation, apoptosis, differentiation and migration of cancer cells, and thus may regulate tumorigenesis and cancer progression. More recently, as a newly discovered hepatocyte factor, EDA pathway has been demonstrated to be involved in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and type II diabetes by regulating glucose and lipid metabolism. In this review, we summarize the function of EDA signaling from skin appendage development to multiple other diseases, and discuss the clinical application of recombinant EDA protein as well as other potential targets for disease intervention.

In mice, rats, dogs and humans, the growth and function of sebaceous glands and eyelid Meibomian glands depend on the ectodysplasin signalling pathway. Mutation of genes encoding the ligand EDA, its transmembrane receptor EDAR and the intracellular signal transducer EDARADD leads to hypohidrotic ectodermal dysplasia, characterised by impaired development of teeth and hair, as well as cutaneous glands. The rodent ear canal has a large auditory sebaceous gland, the Zymbal's gland, the function of which in the health of the ear canal has not been determined. We report that EDA-deficient mice, EDAR-deficient mice and EDARADD-deficient rats have Zymbal's gland hypoplasia. EdaTa mice have 25% prevalence of otitis externa at postnatal day 21 and treatment with agonist anti-EDAR antibodies rescues Zymbal's glands. The aetiopathogenesis of otitis externa involves infection with Gram-positive cocci, and dosing pregnant and lactating EdaTa females and pups with enrofloxacin reduces the prevalence of otitis externa. We infer that the deficit of sebum is the principal factor in predisposition to bacterial infection, and the EdaTa mouse is a potentially useful microbial challenge model for human acute otitis externa., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2022. Published by The Company of Biologists Ltd.)

Background: This case report presents the dimensional changes in dental arches in a patient with hypohidrotic ectodermal dysplasia (HED) after complete denture rehabilitation, with an 18-year follow-up period., Case Report: The patient had complete anodontia and was successfully rehabilitated with conventional complete dentures at 3, 4, 5, 7, 9, 12, 16, and 21 years of age. Each successive denture was larger and contained more and larger teeth so as to accommodate for the increase in the size of the developing jaw. A series of diagnostic casts were used to measure the dimensional changes in the arch length and width of the alveolar ridge. Cast analysis revealed that there was an increase in arch length and width in both the maxilla and mandible over time. Cephalometric analysis of craniofacial development was performed at 21 years of age, and suggested protrusion of the maxilla and mandible., Conclusions: The absence of teeth due to HED did not affect the dimensional changes in dental arches after complete denture rehabilitation from childhood to adulthood. The prosthetic treatment improved the patient's social integration and enabled the development of normal dietary habits, speech, and facial esthetics, which in turn led to improved quality of life.

Hypohidrotic ectodermal dysplasia (HED) is a genetic disorder characterized by hypohidrosis, hypodontia, and hypotrichosis. Autosomal forms of the disease are caused by mutations in either EDAR or EDARADD. To date, the underlying pathomechanisms for HED resulting from EDARADD mutations have not fully been disclosed. In this study, we performed detailed in vitro analyses in order to characterize three dominantly inherited missense mutations, p.D120Y, p.L122R, and p.D123N, and one recessively inherited missense mutation, p.E152K, in the EDARADD gene. Nuclear factor (NF)-κB reporter assays demonstrated that all the mutant EDARADD showed reduction in activation of NF-κB. Importantly, p.D120Y-, p.L122R-, and p.D123N-mutant EDARADD slightly reduced the NF-κB activity induced by wild-type EDARADD in a dominant negative manner. Co-immunoprecipitation assays showed that all of the mutant EDARADD were capable of binding to EDAR and wild-type EDARADD. Additional co-immunoprecipitation assays revealed that p.D120Y-, p.L122R-, and p.D123N-mutant EDARADD markedly prevented the interaction between EDAR and wild-type EDARADD, which further indicated a dominant negative effect by these mutations. Finally, we found that p.D120Y-, p.L122R-, and p.D123N-mutant EDARADD completely lost the ability to bind with TRAF6, while p.E152K-mutant EDARADD showed a mild reduction in the affinity. Our findings will provide crucial information toward unraveling the molecular mechanisms how EDARADD gene mutations cause the disease., (© 2021 Japanese Dermatological Association.)

Background: Hypohidrotic ectodermal dysplasia (HED) is a group of genodermatoses in which deficient ectodysplasin A signalling leads to maldevelopment of skin appendages, various eccrine glands, and teeth. Individuals with HED often have disrupted epithelial barriers and, therefore, were suspected to be more susceptible to coronavirus infection., Methods: 56 households with at least one member who had coronavirus disease of 2019 (COVID-19) were enrolled in a longitudinal study to compare the course of illness, immune responses, and long-term consequences of severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection in HED patients (n = 15, age 9-52 years) and control subjects of the same age group (n = 149)., Results: In 14 HED patients, mild or moderate typical COVID-19 symptoms were observed that lasted for 4-45 days. Fever during the first days sometimes required external cooling measures. The course of COVID-19 was similar to that in control subjects if patients developed antibodies blocking the SARS-CoV-2 spike protein. Five out of six HED patients with completely abrogated ectodysplasin A signalling (83%) suffered from chronic, in two cases very severe fatigue following COVID-19, while only 25% of HED patients with residual activity of this pathway and 21% of control subjects recovering from COVID-19 experienced postinfectious fatigue. Hair loss after COVID-19 was also more frequent among HED patients (64%) than in the control group (13%)., Conclusions: HED appears to be associated with an increased risk of long-term consequences of a SARS-CoV-2 infection. Preventive vaccination against COVID-19 should be recommended for individuals affected by this rare genetic disorder., (© 2021. The Author(s).)

Genes associated with the WNT pathway play an important role in the etiology of tooth agenesis. Low-density lipoprotein receptor-related protein 6 encoding gene ( LRP6 ) is a recently defined gene that is associated with autosomal dominant inherited tooth agenesis. Here, we aimed to identify novel LRP6 mutations in patients with tooth agenesis and investigate the significance of Lrp6 during tooth development. Using whole-exome sequencing, we identified 4 novel LRP6 heterozygous mutations (c.2292G>A, c.195dup, c.1095dup, and c.1681C>T) in 4 of 77 oligodontia patients. Notably, a patient who carried a nonsense LRP6 mutation (c.2292G>A; p.W764*) presented a hypohidrotic ectodermal dysplasia phenotype. Preliminary functional studies, including bioinformatics analysis and TOP-/FOP-flash reporter assays, demonstrated that the activation of WNT/β-catenin signaling was compromised as a consequence of LRP6 mutations. RNAscope in situ hybridization revealed dynamic and special changes of Lrp6 expression during murine tooth development from E11.5 to E16.5. It was noteworthy that Lrp6 was specifically expressed in the epithelium at E11.5 to E13.5 but was expressed in both dental epithelium and dental papilla from E14.5 and persisted in both tissues at later stages. Our study broadens the mutation spectrum of human tooth agenesis and is the first to identify a LRP6 mutation in patients with hypohidrotic ectodermal dysplasia and reveal the dynamic expression pattern of Lrp6 during tooth development. Information from this study is conducive to understanding the functional significance of Lrp6 on the biological process of tooth development.

Introduction: Hypohidrotic ectodermal dysplasia (HED) is a genetic condition typified by alterations in skin structures including sweat glands, hair, nails, and teeth. Hair findings in HED have been poorly characterized in larger series., Objective: To characterize scalp and hair findings of patients with HED clinically and with trichoscopy and light microscopy., Methods: A cross-sectional study in 21 pediatric HED patients was performed using available clinical and scalp dermatoscopic images, as well as pulled-hair samples for clinical evaluation, trichoscopic, and light microscopic analyses., Results: Seventeen out of 21 patients (81%) were men. Twenty patients had straight hair. Sixteen patients had decreased hair density, 6 of whom had hair loss mainly in the temporal and occipital regions. Fourteen patients had hair whorls. On trichoscopy, we observed: single-hair follicular units (n = 19, 90%), scalp hyperpigmentation (n = 13, 62%), variable diameter of the hair shafts (n = 12, 57%), perifollicular scales (n = 8, 38%), scalp erythema (n = 8, 38%), and short curly pigtail hairs (n = 6, 29%). On light microscopy, findings included: hair shafts with irregular diameter (n = 7, 33%), heterogeneous hair color (n = 6, 29%), trichoptilosis (n = 2, 10%), and pili torti (n = 1, 5%)., Conclusions: In this series, hair findings in HED were similar to those described in previous studies. However, we describe two new clinical and two trichoscopic findings: decreased hair density mainly in the temporal and occipital regions, oblique upwards occipital hair follicles orientation, angled hairs, and short curly pigtail hairs. These heterogeneous findings may reflect the multiple factors and signaling pathways that can be affected in these syndromes., (© 2020 Wiley Periodicals LLC.)