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The effect of IQGAP1 on Xenopus embryonic ectoderm requires Cdc42.

IQGAP1 contains a number of protein recognition motifs through which it binds to targets. Several in vitro studies have documented that IQGAP1 interacts directly with calmodulin, actin, E-cadherin, beta-catenin, and the small GTPases Cdc42 and Rac. Nevertheless, direct demonstration of in vivo function of mammalian IQGAP1 is limited. Using a novel assay to evaluate in vivo function of IQGAP1, we document here that microinjection of IQGAP1 into early Xenopus embryos generates superficial ectoderm lesions at late blastula stages. This activity was retained by the mutated variants of IQGAP1 in which the calponin homology domain or the WW domain was deleted. By contrast, deletion of the IQ (IQGAP1-DeltaIQ), Ras-GAP-related (IQGAP1-DeltaGRD), or C-terminal (IQGAP1-DeltaC) domains abrogated the effect of IQGAP1 on the embryos. None of the latter mutants bound Cdc42, suggesting that the binding of Cdc42 by IQGAP1 is critical for its function. Moreover, overexpression of IQGAP1, but not IQGAP1-DeltaGRD, significantly increased the amount of active Cdc42 in embryonic cells. Co-injection of wild type IQGAP1 with dominant negative Cdc42, but not the dominant negative forms of Rac or Rho, blocked the effect of IQGAP1 on embryonic ectoderm. Together these data indicate that the activity of IQGAP1 in embryonic ectoderm requires Cdc42 function.

Animals↗

Role of TRAF3 and -6 in the activation of the NF-kappa B and JNK pathways by X-linked ectodermal dysplasia receptor.

X-linked ectodermal dysplasia receptor (XEDAR) is a recently isolated member of the tumor necrosis factor receptor family that has been shown to be highly expressed in ectodermal derivatives during embryonic development and binds to ectodysplasin-A2 (EDA-A2). By using a subclone of 293F cells with stable expression of XEDAR, we report that XEDAR activates the NF-kappaB and JNK pathways in an EDA-A2-dependent fashion. Treatment with EDA-A2 leads to the recruitment of TRAF3 and -6 to the aggregated XEDAR complex, suggesting a central role of these adaptors in the proximal aspect of XEDAR signaling. Whereas TRAF3 and -6, IKK1/IKKalpha, IKK2/IKKbeta, and NEMO/IKKgamma are involved in XEDAR-induced NF-kappaB activation, XEDAR-induced JNK activation seems to be mediated via a pathway dependent on TRAF3, TRAF6, and ASK1. Deletion and point mutagenesis studies delineate two distinct regions in the cytoplasmic domain of XEDAR, which are involved in binding to TRAF3 and -6, respectively, and play a major role in the activation of the NF-kappaB and JNK pathways. Taken together, our results establish a major role of TRAF3 and -6 in XEDAR signaling and in the process of ectodermal differentiation.

Amino Acid Sequence↗

Genetic mapping of canine multiple system degeneration and ectodermal dysplasia loci.

We characterized a movement disorder of Chinese Crested dogs clinically and pathologically indistinguishable from canine multiple system degeneration (CMSD) previously recognized in Kerry Blue Terriers. This fatal disease segregated as an autosomal recessive in a 51-dog pedigree of both breeds and their crosses. The occurrence of affected dogs among first-generation crosses demonstrated that the mutations causing multiple system degeneration in these breeds are allelic. The CMSD locus maps to CFA1 (LOD > 18) and haplotype analysis narrowed the CFA1 target region to a 15-Mb segment that contains orthologs of genes on HSA6, including PARK2, the gene for the ubiquitin ligase parkin. Mutations in human PARK2 cause the most common form of familial Parkinson's disease, autosomal recessive juvenile parkinsonism, which has clinical and pathological similarities to canine multiple system degeneration. A second phenotype, canine ectodermal dysplasia (CED), segregated in the pedigree as an autosomal dominant with homozygous lethality. Dogs with ectodermal dysplasia have a sparse hair coat and abnormal dentition that is characteristic of the "hairless" variety of Chinese Cresteds. CED mapped to a region of CFA17 (LOD > 14) containing orthologs from HSA2. EDAR, the gene for the ectodysplasin A1 receptor, occurs on HSA2 but was excluded as the cause of canine ectodermal dysplasia.

Animals↗

Development of teratomas from the ectoderm of mouse egg cylinders.

We studied the developmental capacities of the primary ectoderm and endoderm of 6-day embryos of hybrids between strains 129/Sv-SIJ C P and A/He mice by grafting these germ layers into the testes of adult mice for 30 days. Grafts of embryonic ectoderm gave rise to teratocarcinomas composed of undifferentiated embryonal cells and derivatives of all three germ layers including respiratory and alimentary epithelium. Grafts of extraembryonic ectoderm gave rise to invasive trophoblastic giant cells. Grafts of endoderm did not develop.

Animals↗

Breast reconstruction in ectodermal dysplasia.

Patients with ectodermal dysplasia may request breast reconstruction. In addition to abnormalities of other ectodermally derived structures, the breast and nipple-areolar complex may be absent or hypoplastic. Although this group of patients may have concerns with hair, nails, teeth, or even upper limb malformations, this report focuses on reconstruction of the breast anomalies. Four unrelated patients with ectodermal dysplasia who have undergone breast reconstruction are discussed.

Adult↗

Familial subungual keratoacanthoma in association with ectodermal dysplasia.

Described is the first report of familial SUKA, occurring in two of three sisters with ectodermal dysplasia, a rare, hereditary disorder involving ectodermally derived organ systems. Although rare, SUKA should be considered when assessing rapidly growing nailbed lesions. Differentiation from subungual squamous cell carcinoma is essential. Tumor excision and curettage and close postoperative follow-up are recommended, with conservative amputation reserved for tumor recurrences. If the diagnosis of SUKA is confirmed in a female, an association with ectodermal dysplasia should be sought.

Adult↗

Establishment of ventral cell fates in the Drosophila embryonic ectoderm requires DER, the EGF receptor homolog.

The embryonic ectoderm in Drosophila displays a highly organized arrangement of specific structures along the dorsal-ventral axis. To establish this characteristic design, cells must receive instructive cues regarding their position. We present evidence that during stages 8-9 of embryonic development, the Drosophila EGF receptor homolog (DER) is essential for determining the identity of cells within the ventral ectoderm. In the absence of DER activity at this phase, alterations in cell fate are observed: Ventral cells acquire more dorsal fates, as visualized by the expression profile of specific markers. The ventralizing effect of DER appears to function later than that of the dorsalizing dpp pathway, and the spatial overlap between them is minimal. A model for the determination of cell fates along the dorsal-ventral axis involving the two pathways is presented. Some aspects of the mutant ectodermal and CNS phenotypes of the DER locus (faint little ball, flb) resemble the phenotype of mutations from the spitz group. Synergistic interactions between flb and spitz or Star mutations suggest that these genes participate in a common signaling pathway.

Animals↗

Unusual cutaneous manifestations of anhidrotic ectodermal dysplasia--a case report.

Congenital ectodermal dysplasia is a group of familial disorders that affect tissues and organs of ectodermal origin to varying degrees. Our patient with classical X-linked anhidrotic ectodermal dysplasia (AED) showed unusual skin manifestations including cafe-au-lait spots on the face, neck, buttock, and lumbo-sacral region; depigmentation of mucous membrane of the lower lip, buccal cavity, and left arm; absence of tragii; plantar keratoderma; and kyphosis of lower cervical and upper thoracic spines which have not been previously reported in the world literature.

Adult↗

A case of hypohidrotic ectodermal dysplasia.

Hypohidrotic ectodermal dysplasia (HED) is a rare, hereditary, congenital disease that affects several ectodermal structures. It is characterised by the following: anhidrosis or hypohidrosis, dental abnormalities, hypotrichosis, and a characteristic facies. The face shows prominent frontal bosses, supraorbital ridges and depressed bridges. We experienced a case of hypohidrotic ectodermal dysplasia in a 43-year-old male who had four characteristic features. A skin biopsy from the palm showed a total absence of the eccrine glands. The diagnosis was made on the basis of clinical features and skin biopsy findings.

Adult↗

Scalp dermatitis, distinctive hair abnormalities and atopic disease in the ectrodactyly-ectodermal dysplasia-clefting syndrome.

We report a 2-year-old girl with a combination of the ectodermal dysplasia, ectrodactyly, cleft lip/palate (EEC) syndrome, distinctive hair abnormalities, scalp dermatitis and atopic disease. To our knowledge, this is the first report of scalp dermatitis in the EEC syndrome. Distinctive structural hair abnormalities shared by the syndromes of ectodermal dysplasia and clefting are helicotrichia, pili torti et canaliculi, and cuticle defects, all of which were observed in the present case. A high incidence of atopic disease in certain subsets of ectodermal dysplasia has been reported. In our patient this manifested as food-induced exacerbation of atopic dermatitis, associated with positive prick tests and significant levels of circulating specific IgE.

Abnormalities, Multiple↗

A novel 7-bp deletion mutation in a Taiwanese family with X-linked hypohidrotic ectodermal dysplasia.

Hypohidrotic ectodermal dysplasia (HED) is found worldwide with an estimated incidence of 1 per 100,000 births. X-linked hypohidrotic ectodermal dysplasia (XLHED, OMIM 305100) is the most common form of the ectodermal dysplasias (ED), a rare group of hereditary diseases characterized by abnormal development of eccrine sweat glands, hair, and teeth. Heterozygous carriers of XLHED often manifest minor or moderate degrees of hypotrichosis, hypodontia, and hypohidrosis. ED1, the gene for XLHED encodes ectodysplasin A, which is a new member of the tumour necrosis factor family. The majority of mutations in XLHED are missense mutations, but one-fifth are insertion/deletions. Here we report a novel 7-bp deletion mutation (nt1242-1248) in exon 9 of the ED1 gene that results in a frameshift and premature stop codon (PTC + 38 amino acids). Mutation analysis in families with XLHED allows for genetic counselling, prenatal diagnosis and confirmation of carrier status.

Adult↗

De novo missense mutation, S541Y, in the p63 gene underlying Rapp-Hodgkin ectodermal dysplasia syndrome.

Rapp-Hodgkin syndrome (RHS) is an autosomal dominant disorder characterized by ectodermal dysplasia and cleft lip/cleft palate. Very recently, mutations in p63 have been identified as a cause of RHS; to date five such mutations have been identified. We describe a Thai girl with RHS. She had short stature, ectodermal dysplasia, epiphora, cleft lip, cleft palate, and normal development. Mutation analysis for the entire coding region of p63 identified a novel and de novo mutation, 1622C--> A (S541Y), in the SAM domain, predicting an abnormal alpha tail of the p63alpha protein isotypes. This observation supports that majority of patients with RHS are caused by mutations affecting the tail of p63alpha, a region that also contains most of the pathogenic mutations in ankyloblepharon-ectodermal dysplasia-clefting (AEC) syndrome.

Abnormalities, Multiple↗

Growth analysis of a patient with ectodermal dysplasia treated with endosseous implants: 6-year follow-up.

The purpose of this article is to report the clinical course and 6-year follow-up of a child with ectodermal dysplasia who was treated with implants surgery very early. This article reports placement of mandibular endosseous implants in a 4-year-old patient with hypohidrotic ectodermal dysplasia and oligodontia. This congenital anomaly does not appear to retard healing and the osseointegration remains after 6 years and 3 months of loading. Mandibular and maxillary skeletal growth and development was normal. However, because of lack of alveolar growth, in time, patient's vertical growth pattern changed to low angle. This could be corrected by changing the vertical heights of the abutment and prosthesis. As a result, in ectodermal dysplasias cases with anadontia, early implant placement and fixed prosthesis could be a good multidisciplinary treatment option for poor cooperative child.

Cephalometry↗

The management of ectodermal dysplasia and severe hypodontia. International conference statements.

An international conference on ectodermal dysplasias and hypodontia, held in London in 2004, featured a session devoted to the management of the ectodermal dysplasias and severe hypodontia. This paper presents a set of statements prepared by an international specialist panel, including representatives of patient support groups, who presented and subsequently debated a series of papers on this subject. The following topics were explored: potential roles of patient support groups; core care standards, including the roles and composition of medical and dental multidisciplinary teams for treating these conditions; the format of a baseline data set for patients with an ED; and priorities for research in ectodermal dysplasias, with particular regard to laboratory and clinical studies, and research methodology. The statements are intended to form an international framework for developing patient care pathways, and collaborative research in this field.

Anodontia↗

A novel missense mutation (402C-->T) in exon 1 in the EDA gene in a family with X-linked hypohidrotic ectodermal dysplasia.

Hypohidrotic ectodermal dysplasia (EDA), or Christ-Siemens-Touraine syndrome, is clinically characterized by hypohidrosis, hypoodontia and hypotrichosis. The X-linked form of the disease has been mapped to Xq12-q13.1, and a gene from this region has recently been cloned. This gene encodes a predicted transmembrane protein of 135 amino acids, which was found to be expressed in keratinocytes, hair follicles, and sweat glands. A variety of rearrangements in this gene have been found in patients with hypohidrotic ectodermal dysplasia. We have screened the probands from nine unrelated Danish families with hypohidrotic ectodermal dysplasia for mutation in exon 1 of the EDA-gene by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). In one large kindred we identified a novel missense mutation (402C-->T), which changes a histidine to tyrosine at position 54 in the protein. This mutation cosegregates with the disease in the family and is the first mutation described which affects the predicted transmembrane, hydrophobic domain of the protein.

Amino Acid Sequence↗

Structural hair abnormalities in ectodermal dysplasia.

The hair of patients with three ectodermal dysplasias--ectrodactyly ectodermal dysplasia clefting syndrome (EEC); orofacial-digital syndrome (OFD) type I; and anhidrotic ectodermal dysplasia syndrome (AED)--were studied by scanning electron microscopy. While no pathognomonic abnormalities were noted for each condition, hair shaft structural defects were evident in all patients studied. The EEC clefting syndrome and OFD I shared the most deforming defects, while AED had fewer.

Abnormalities, Multiple↗

Loose anagen hair in hypohidrotic ectodermal dysplasia.

We report a 4 year-old boy affected with hypohidrotic ectodermal dysplasia in whom loose anagen hair syndrome (LAHS) was suspected clinically. The diagnosis was confirmed by examination of hair by optic and scanning electron microscopy. Loose anagen hairs have not been previously described in the ectodermal dysplasias. It is possible that our patient had real LAHS or an ectodermal dysplasia with loose anagen hair as an epiphenomenon.

Child, Preschool↗

A child with hypohidrotic ectodermal dysplasia with features of a collodion membrane.

Collodion membrane is a presenting phenotype common to several disorders, predominantly congenital ichthyoses. Seventy percent of infants born with hypohidrotic (anhidrotic) ectodermal dysplasia are noted by their parents to have significant scaling and peeling. Although dry skin is a frequently reported sign in children with hypohidrotic ectodermal dysplasia, only one French study has reported a true collodion membrane at birth. We suspect that scaling with features of collodion membrane is more common in infants than is reflected in the literature, and we describe another such infant, later diagnosed with hypohidrotic ectodermal dysplasia.

Ectodermal Dysplasia↗