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PubMed1988

Genetic counselling in hypomelanosis of Ito: case report and review.

A 27-year-old male with hypomelanosis of Ito (HI) is reported. One of his two children had a postaxial ray defect of one leg but neither had cutaneous features of HI. Somatic mosaicism for a gene defect lethal to ectodermal derivatives offers the best explanation for HI in males, with consequent negligible recurrence risk. The limb defect is considered coincidental. The excess of girls with HI could be due to a female cohort with incontinentia pigmenti (IP) which may be indistinguishable: counselling of females must therefore take account of possible X-linked inheritance.

Adult↗
PubMed1991

Congenital and hereditary nail disorders.

An accurate description of nail changes in congenital and hereditary conditions is complicated both by vague terminology and by errors introduced by the effects of trauma. This article attempts to identify primary developmental abnormalities in the nails and divides them into those caused by defects in the nail matrix, the nail field, or the nail bed and those originating from combined ectodermal and mesodermal defects. Attempting to identify underlying embryological defects may allow a more logical approach to both description and classification of congenital and hereditary nail abnormalities.

Humans↗
PubMed2004

[Anhydrotic ectodermal dysplasia as cause of recurrent hyperthermia in a 5 month old infant].

The X-linked anhydrotic ectodermal dysplasia is a rare disease in which defects in development of ectodermal derivatives are observed. This syndrome is clinically characterized by total or partial anodontia, characteristic physionomy and absent or reduced sweating. Recurrent fever was a clue to the disease diagnosis in 5 month old infant. The diagnosis was confirmed by the mutation of EDA exon 9.

Anodontia↗
PubMedDate not supplied

Mutation of the ectodysplasin-A gene results in bone defects in mice.

Anhidrotic ectodermal dysplasia (EDA) is an X-linked, recessive genetic disease characterized by dysfunctional sweat glands, poorly developed teeth, and premature balding in human beings. This disorder results from mutations in the gene for ectodysplasin-A, a type II transmembrane protein with tumour necrosis factor-alpha domains. An animal model of EDA, the Tabby mouse, also has mutations in the ectodysplasin-A gene and defects similar to those of human beings with EDA. In addition to these defects, Tabby mice acquire deformities in the distal portion of their tails at 10-12 weeks of age. Whole-mount staining of the skeleton with Alizarin Red and Alcian Blue revealed that the tail defect resulted from vertebral fractures just distal to the epiphysis. Histological analysis demonstrated that the structure of both the epiphysis and the subepiphyseal zone of the tail vertebrae was dysplastic while the shaft of the diaphysis was relatively normal. The overall structure of the trabecular bone of these animals was examined through 3-dimensional microcomputed tomography of the tibia. This analysis indicated that Tabby mice had a mild increase in the interconnectivity of the intertwined trabecular bone network but that individual trabeculae were relatively normal. Since it has been determined recently that the ectodysplasin-A gene is expressed in the osteoblasts of developing human embryos, it appears likely that this gene plays a role in normal bone development.

Animals↗
PubMed1998

Defect in the maintenance of the apical ectodermal ridge in the Dactylaplasia mouse.

During vertebrate limb development the distal apex of the limb bud ectoderm is induced to form the apical ectodermal ridge (AER). The presence of the AER is required for the continued outgrowth of the limb bud. Classical embryological studies have led to the hypothesis that a secreted mesenchymal factor is required to maintain the AER. We have undertaken a detailed analysis of Dactylaplasia (Dac) mice, a semidominant mutant which displays missing central digits in the fore- and hindlimbs of heterozygous animals and monodactyly in homozygous animals. Our data show that Dac mice have a defect in the maintenance of the AER. At E10.5, the mutant AER is found to be morphologically normal. However, by E11.5 the central aspect of the AER degenerates leaving the anterior and posterior AER intact. In homozygous mice both the central and anterior AER degenerate, while the posterior extremity of the AER is unaffected. Analysis of BrdU incorporation reveals that degeneration of the AER is due to a lack of cell proliferation in the mutant AER. The loss of the AER leads to a reduction in cell proliferation in the subridge mesenchyme at E11.5. The data represent direct genetic evidence for the existence of an AER maintenance activity that is distinct from AER induction and differentiation. Moreover, the data suggest that the role of the AER maintenance factor is to promote cell proliferation in the ridge. Based on our findings, we propose a model for AER maintenance in the vertebrate limb.

Animals↗
PubMed1999

Hidrotic ectodermal dysplasia with corneal involvement.

BACKGROUND: Persons with ectodermal dysplasias classically have defects in hair, teeth, nails, and sweat glands. Other tissues derived from ectoderm may also be involved. Ocular involvement in ectodermal dysplasias primarily occurs in anhidrotic forms. METHODS: We describe a father and son with hidrotic ectodermal dysplasia. RESULTS: Both patients had recurrent corneal epithelial defects from birth, corneal neovascularization, and strabismus. The father had cataracts with crystalline and amorphous inclusions at an early age. Both patients also had alopecia and skin abnormalities. CONCLUSIONS: A father and son with a previously unreported hidrotic ectodermal dysplasia and unusual corneal findings are described.

Adult↗
PubMed1993

Pili torti with congenital deafness (Bjornstad's syndrome)--report of three cases in one family, suggesting autosomal dominant transmission.

Pili torti is a rare hair shaft abnormality in which the hair is flattened and intervals twisted at irregular through 180 degrees about its axis. Pili torti may occur as a congenital defect or as an acquired disorder (secondary to patchy alopecia from a variety of causes). When it is congenital, it may be isolated and determined by an autosomal dominant gene or associated with various rare syndromes, including ectodermal dysplasias, neurological defects and metabolic disturbances. The association of neurosensory hearing loss and pili torti has been recognized as Bjornstad's syndrome since 1965. As far as we know, only 15 cases of this syndrome have been reported. We describe here three cases of Bjornstad's syndrome in one family.

Adolescent↗
PubMed2000

Normal thymic architecture and negative selection are associated with Aire expression, the gene defective in the autoimmune-polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED).

T cell development is tightly controlled by thymic stromal cells. Alterations in stromal architecture affect T cell maturation and the development of self-tolerance. The monogenic autoimmune syndrome APECED (autoimmune-polyendocrinopathy-candidiasis-ectodermal dystrophy) is characterized by the loss of self-tolerance to multiple organs. Although mutations in the autoimmune regulator (AIRE) gene are responsible for this disease, the function of AIRE is not known. Here we report on the spatial and temporal pattern of murine Aire expression during thymic ontogeny and T cell selection. Early during development, thymic Aire transcription is critically dependent on RelB and occurs in epithelial cells in response to lymphocyte-mediated signals. In adult tissue, Aire expression is confined to the medulla and the corticomedullary junction, where it is modulated by thymocytes undergoing negative selection. Aire may determine thymic stromal organization and with it the induction of self-tolerance.

Animals↗
PubMed2004

Ectodermal dysplasias.

Ectodermal dysplasias are a large group of heritable conditions characterized by congenital defects of one or more ectodermal structures and their appendages: hair (hypotrichosis, partial, or total alopecia), nails (dystrophic, hypertrophic, abnormally keratinized), teeth (enamel defect or absent), and sweat glands (hypoplastic or aplastic). The ectodermal dysplasias, as a rule, are not pure "one-layer diseases." Mesodermal and, rarely, endodermal dysplasias coexist. Embryogenesis exhibits distinct tissue organizational fields and specific interactions among the germ layers that may lead to a wide range of ectodermal dysplasias when genes important for development are mutated or otherwise altered in expression. Of the approximately 200 different ectodermal dysplasias, about 30 have been studied at the molecular level with identification of the causative gene. Freire-Maia and Pinheiro used the clinical aspects for their classification, and Priolo integrated molecular genetic and clinical aspects for her scheme. Those two more historical classification schemes have the difficulty that, when applied strictly, several additional groups of diseases should be integrated within the term "ectodermal dysplasias," e.g. keratodermas with skin or hair alterations or the ichthyoses with associated features. Such consequent classification would lead to an endless list of diseases and would be useless for the practical work. Recent evidence implicates a genetic defect in different pathways orchestrating ectodermal organogenesis. Modern molecular genetics will increasingly elucidate the basic defects of the different syndromes and yield more insight into the regulatory mechanisms of embryology. In this way, a reclassification of ectodermal dysplasias will be possible according to the function of their involved mutated genes. Lamartine recently proposed a helpful classification according to the functions of the genes discovered in different types of ectodermal dysplasias. Accordingly, the present overview categorizes the various ectodermal dysplasias into four major functional subgroups: cell-cell communication and signaling, adhesion, transcription regulation, and development.

Cell Adhesion↗
PubMed1994

Isolated congenital atrichia in an Omani kindred.

Congenital atrichia may occur isolated or with associated defects. The isolated variant is especially uncommon. Sporadic and familial cases have been rarely reported. We present a large inbred kindred from Oman where 22 affected members with this disorder were found over six generations. The male-to-female ratio was 1:1.4. No associated ectodermal or other defects were noted. A typical autosomal recessive mode of inheritance was documented. Though inbreeding was high, anticipated quasidominance was observed only once.

Alopecia↗
PubMed1997

Drosophila myoblast city encodes a conserved protein that is essential for myoblast fusion, dorsal closure, and cytoskeletal organization.

The Drosophila myoblast city (mbc) locus was previously identified on the basis of a defect in myoblast fusion (Rushton et al., 1995. Development [Camb.]. 121:1979-1988). We describe herein the isolation and characterization of the mbc gene. The mbc transcript and its encoded protein are expressed in a broad range of tissues, including somatic myoblasts, cardial cells, and visceral mesoderm. It is also expressed in the pole cells and in ectodermally derived tissues, including the epidermis. Consistent with this latter expression, mbc mutant embryos exhibit defects in dorsal closure and cytoskeletal organization in the migrating epidermis. Both the mesodermal and ectodermal defects are reminiscent of those induced by altered forms of Drac1 and suggest that mbc may function in the same pathway. MBC bears striking homology to human DOCK180, which interacts with the SH2-SH3 adapter protein Crk and may play a role in signal transduction from focal adhesions. Taken together, these results suggest the possibility that MBC is an intermediate in a signal transduction pathway from the rho/rac family of GTPases to events in the cytoskeleton and that this pathway may be used during myoblast fusion and dorsal closure.

Amino Acid Sequence↗
PubMedDate not supplied

[Libernan-Cole-Golts syndrome. Focal dermic hypoplasia. Report of a case].

A case is reported corresponding to the so-called focal dermic hypoplasia and that we have named Liberman-Cole-Goltz syndrome. This is possibly the fourth case published in Mexican literature and is an additional report to those described in the international literature. This syndrome is characterized by variable ectodermal and mesodermal defects with congenital lesions most frequently found in skin and in the skeleton. The clinical, radiological and histopathological finds in the case studied are pointed out.

Abnormalities, Multiple↗
PubMed2005

Edar signaling in the control of hair follicle development.

Ectodysplasin receptor Edar and its ligand Eda A1, as well as their related receptor Xedar and ligand Eda A2, are recently discovered members of the tumor necrosis factor superfamily that signal predominantly through the nuclear factor-kappaB and c-jun N-terminal kinases pathways. Mutations in genes that encode proteins involved in Edar signaling pathway cause hypohidrotic ectodermal displasias in humans and mice and characterized by severe defects in development of ectodermal appendages including hairs, teeth, and exocrine glands. Here, we summarize the current knowledge of molecular mechanisms underlying the involvement of Edar signaling pathway in controlling hair follicle (HF) development and cycling. Genetic and experimental studies suggest that Edar signaling is involved in the control of cell fate decision in embryonic epidermis, as well as in the regulation of cell differentiation programs in the HF. Loss or gain of Edar signaling affects the initiation of several HF types (guard and zig-zag HF), hair shaft formation, as well as sebaceous gland morphology. We also review data on the cross-talk between Edar and Wnt, transforming growth factor-beta/bone morphogenic protein/activin, and Shh signaling pathways in the control of HF development and cycling.

Animals↗
PubMed2001

Craniofacial tissues including tooth buds in fetal hypohidrotic ectodermal dysplasia.

OBJECTIVE: Hypohidrotic ectodermal dysplasia (HED) comprises defects in hair, teeth, and sweat glands. Disturbances in other ectodermal tissues have been associated with the condition. Our objective was to examine ectodermal craniofacial structures histologically in a fetus with HED and to compare the findings to similar structures in normal control fetuses. MATERIALS AND METHODS: A male fetus diagnosed with HED was therapeutically aborted in the 15th week of gestation. One male and two female healthy fetuses were used as normal controls. All fetuses were examined with parental consent, and had comparable sizes. Their bone maturation stage in the hand was identical. Tissue blocks from the craniofacial region were excised from all fetuses and prepared for histological analysis (formalin fixed, stained with toluidine blue or Alcian blue). The tissues examined were: tooth buds, skin and skin appendages, oral mucosa including minor salivary glands, major salivary glands, lacrimal glands, and adenohypophysis. RESULTS: Fewer tooth buds, minor salivary glands, and hair follicles were observed in the HED fetus as compared to controls. The structures of the epidermal components in the developing HED organs were loose and disorganised. The adhesion between the ectodermal and mesenchymal organ components in the HED fetus seemed to be disturbed.

Ectodermal Dysplasia↗
PubMedDate not supplied

Keratitis, ichthyosis, and deafness (KID syndrome): review of the literature and proposal of a new terminology.

The so-called KID (keratitis, ichthyosis, deafness) syndrome is a congenital disorder of ectoderm that affects not only the epidermis, but also other ectodermal tissues such as the corneal epithelium and the inner ear. Sixty-one patients who fulfill the criteria for this syndrome were identified in a review of the literature through December 1993. All had cutaneous and auditory abnormalities, and 95% also had ophthalmologic defects. The most frequent clinical features were neurosensory deafness 90%, erythrokeratoderma 89%, vascularizing keratitis 79%, alopecia 79%, and reticulated hyperkeratosis of the palms and soles 41%. All of these findings constitute the major criteria for the diagnosis. The KID acronym does not accurately define this entity since the disorder is not an ichthyosis, because scaling is not the main cutaneous feature and not all patients have keratitis early in the course. We suggest that this syndrome should be included under the general heading of congenital ectodermal defects as a keratodermatous ectodermal dysplasia (KED).

Adult↗
PubMed2002

Zebrafish DeltaNp63 is a direct target of Bmp signaling and encodes a transcriptional repressor blocking neural specification in the ventral ectoderm.

Bone morphogenetic proteins (Bmps) promote ventral specification in both the mesoderm and the ectoderm of vertebrate embryos. Here we identify zebrafish DeltaNp63, encoding an isoform of the p53-related protein p63, as an ectoderm-specific direct transcriptional target of Bmp signaling. DeltaNp63 itself acts as a transcriptional repressor required for ventral specification in the ectoderm of gastrulating embryos. Loss of DeltaNp63 function leads to reduced nonneural ectoderm followed by defects in epidermal development during skin and fin bud formation. In contrast, forced DeltaNp63 expression blocks neural development and promotes nonneural development, even in the absence of Bmp signaling. Together, DeltaNp63 fulfills the criteria to be the neural repressor postulated by the "neural default model."

Animals↗