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PubMedDate not supplied

Microanatomy of the dental enamel in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED): report of three cases.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is an autosomal recessive disease composed of failure of various endocrine glands, chronic mucocutaneous candidiasis, and an ectodermal dystrophy complex including hypoplasia of the dental enamel. To characterize the enamel defect further, we studied enamel microanatomy by light microscopy and scanning electron microscopy in clinically affected permanent teeth from three APECED patients. In all three cases, the enamel was partially hypoplastic and morphologically aberrant. Hypoplasia was evident as a horizontal band or as rows of pits. The incremental pattern in the abnormal enamel was obscure, and the prisms were either barely detectable or accentuated and disoriented. In scanning electron microscopy, imprints of the Tomes processes were seen on the enamel surface, but the perikymata were poorly contoured. The distribution pattern of the defective enamel corresponded to the sequence of tooth development and was suggestive of a transient insult. In the enamel affected with a hypoplastic pitted from of amelogenesis imperfecta, studied for comparison, only local hypoplastic defects were seen. Together with normal parathyroid function in one patient and normal calcification of dentin in one of the two patients with hypoparathyroidism, morphology of the enamel in APECED appears to preclude calcium deficiency as the primary cause of the enamel dystrophy.

Adolescent↗
PubMed1979

[Ectodermal dysplasia and exocrine pancreatic insufficiency--a familial syndrome].

A syndrome was observed in two sisters which was characterized by a median defect of the hair of the head, hypoplasia of the ala nasi, absence of the permanent teeth, microdontia of the deciduous teeth, and exocrine insufficiency of the pancreas. This syndrome is probably autosomal regressive; the symptoms are similar to those of Johanson-Blizzard syndrome.

Child↗
PubMed1991

Sweat testing to identify female carriers of X linked hypohidrotic ectodermal dysplasia.

X linked hypohidrotic ectodermal dysplasia (XHED) affects many epithelial functions, including sweat gland formation. Female carriers who manifest XHED may have defective dentition or a patchy distribution of sweating or both, as determined by starch and iodine sweat testing. Such sweat testing can be useful in assigning carrier status to at risk females in XHED families, and in obtaining an accurate diagnosis for isolated females who present with features of ectodermal dysplasia. The advantages of diagnosing female carriers of XHED include the optimisation of neonatal and paediatric care for affected male infants, who may be at substantial risk of death in infancy.

Adult↗
PubMed1996

The limb field mesoderm determines initial limb bud anteroposterior asymmetry and budding independent of sonic hedgehog or apical ectodermal gene expressions.

We have analyzed the pattern of expression of several genes implicated in limb initiation and outgrowth using limbless chicken embryos. We demonstrate that the expressions of the apical ridge associated genes, Fgf-8, Fgf-4, Bmp-2 and Bmp-4, are undetectable in limbless limb bud ectoderm; however, FGF2 protein is present in the limb bud ectoderm. Shh expression is undetectable in limbless limb bud mesoderm. Nevertheless, limbless limb bud mesoderm shows polarization manifested by the asymmetric expression of Hoxd-11, -12 and -13, Wnt-5a and Bmp-4 genes. The posterior limbless limb bud mesoderm, although not actually expressing Shh, is competent to express it if supplied with exogenous FGF or transplanted to a normal apical ridge environment, providing further evidence of mesodermal asymmetry. Exogenous FGF applied to limbless limb buds permits further growth and determination of recognizable skeletal elements, without the development of an apical ridge. However, the cells competent to express Shh do so at reduced levels; nevertheless, Bmp-2 is then rapidly expressed in the posterior limbless mesoderm. limbless limb buds appear as bi-dorsal structures, as the entire limb bud ectoderm expresses Wnt-7a, a marker for dorsal limb bud ectoderm; the ectoderm fails to express En-1, a marker of ventral ectoderm. As expected, C-Lmx1, which is downstream of Wnt-7a, is expressed in the entire limbless limb bud mesoderm. We conclude that anteroposterior polarity is established in the initial limb bud prior to Shh expression, apical ridge gene expression or dorsal-ventral asymmetry. We propose that the initial pattern of gene expressions in the emergent limb bud is established by axial influences on the limb field. These permit the bud to emerge with asymmetric gene expression before Shh and the apical ridge appear. We report that expression of Fgf-8 by the limb ectoderm is not required for the initiation of the limb bud. The gene expressions in the pre-ridge limb bud mesoderm, as in the limb bud itself, are unstable without stimulation from the apical ridge and the polarizing region (Shh) after budding is initiated. We propose that the defect in limbless limb buds is the lack of a dorsal-ventral interface in the limb bud ectoderm where the apical ridge induction signal would be received and an apical ridge formed. These observations provide evidence for the hypothesis that the dorsal-ventral ectoderm interface is a precondition for apical ridge formation.

Animals↗
PubMed1998

Limb development and evolution: a frog embryo with no apical ectodermal ridge (AER).

The treefrog Eleutherodactylus coqui is a direct developer--it has no tadpole stage. The limb buds develop earlier than in metamorphosing species (indirect developers, such as Xenopus laevis). Previous molecular studies suggest that at least some mechanisms of limb development in E. coqui are similar to those of other vertebrates and we wished to see how limb morphogenesis in this species compares with that in other vertebrates. We found that the hind limb buds are larger and more advanced than the forelimbs at all stages examined, thus differing from the typical amniote pattern. The limb buds were also small compared to those in the chick. Scanning and transmission electron microscopy showed that although the apical ectoderm is thickened, there was no apical ectodermal ridge (AER). In addition, the limb buds lacked the dorsoventral flattening seen in many amniotes. These findings could suggest a mechanical function for the AER in maintaining dorsoventral flattening, although not all data are consistent with this view. Removal of distal ectoderm from E. coqui hindlimb buds does not stop outgrowth, although it does produce anterior defects in the skeletal pattern. The defects are less severe when the excisions are performed earlier. These results contrast with the chick, in which AER excision leads to loss of distal structures. We suggest that an AER was present in the common ancestor of anurans and amniotes and has been lost in at least some direct developers including E. coqui.

Animals↗
PubMed1985

Aplasia cutis congenita and intestinal lymphangiectasia. An unusual association.

Aplasia cutis congenita (ACC) is a rare skin defect usually localized to the vertex. It has been reported in association with other disorders involving mainly ectodermal and mesodermal structures. We discovered the association of ACC and intestinal lymphangiectasia (IL) in a patient and probably in his brother. At birth, the propositus had ACC of the vertex and edema, which persisted for six months. At 3 years of age he presented with generalized edema and was found to have hypoproteinemia and lymphopenia. Radioisotope studies and a small-intestinal biopsy confirmed the diagnosis of IL. On a fat-free, medium-chain triglyceride-containing diet, clinical and laboratory findings returned to normal. A sibling born one year after his brother's presentation had nonpitting limb edema and extensive ACC of the vertex with an underlying bony defect. He died in shock at 2 months of age, after sudden profuse bleeding from the sagittal sinus. The association between ACC and IL is another example of combined anomalies with both ectodermal and mesodermal involvement that is most probably not coincidental.

Child, Preschool↗
PubMed1989

A case of cardio-facio-cutaneous syndrome.

A 6-yr-old girl is described who presented with failure to thrive at age 3 months and was found to have mental retardation, growth retardation, disproportionately large head, distinctive face, abnormal hair, eczema, heart defect, splenomegaly, and multiple hemangiomata. She is thought to have the cardio-facio-cutaneous syndrome and to be the first such case identified in Britain.

Abnormalities, Multiple↗
PubMed2005

Oral health of southern Chinese children and adolescents with severe hypodontia.

OBJECTIVE: The aim of this study was to assess the oral health condition of southern Chinese children and adolescents with severe hypodontia. METHODS: This was a cross-sectional clinical study in the dental teaching hospital in Hong Kong. Twenty-five children and adolescents with severe hypodontia, and a comparison group of 25 age- and gender-matched controls took part. Verified clinical examination techniques were used to assess the pattern of missing teeth, tooth spacing, dental caries, periodontal condition, enamel defects, and tooth wear. Statistical comparisons were made between groups using independent Student t-tests and chi-square tests. RESULTS: The mean number of congenitally missing permanent teeth in the severe hypodontia group was 9.1 (SD = 5.0), with the maxillary lateral incisor being the most common missing tooth (14.5%). There were significant space discrepancies in both jaws between groups (P < 0.001). Caries prevalence was low with no difference between groups. There was no difference in periodontal condition between groups, with about half of the participants having no gingival inflammation. The severe hypodontia group had more enamel defects (P = 0.043), enamel hypoplasia (P = 0.044) and tooth wear (P = 0.005) than the comparison group. Three of the severe hypodontia group had ectodermal dysplasia. CONCLUSIONS: The oral health condition of southern Chinese children and adolescents with severe hypodontia was good in terms of caries experience and periodontal health. However, the increased prevalence of developmental defects of enamel and tooth wear complicates already complex interim and definitive prosthodontic management, and may increase psychosocial impact.

Adolescent↗
PubMed2006

A requirement for NF-protocadherin and TAF1/Set in cell adhesion and neural tube formation.

Neurulation in vertebrates is an intricate process requiring extensive alterations in cell contacts and cellular morphologies as the cells in the neural ectoderm shape and form the neural folds and neural tube. Despite these complex interactions, little is known concerning the molecules that mediate cell adhesion within the embryonic neural plate and neural folds. Here, we demonstrate the requirement for NF-protocadherin (NFPC) and its cytosolic partner TAF1/Set for proper neurulation in Xenopus. Both NFPC and TAF1 function in cell-cell adhesion in the neural ectoderm, and disruptions in either NFPC or TAF1 result in a failure of the neural tube to close. This neural tube defect can be attributed to a lack of proper organization of the cells in the dorsal neural folds, manifested by a loss in the columnar epithelial morphology and apical localization of F-actin. However, the epidermal ectoderm is still able to migrate and cover the open neural tube, indicating that the fusions of the neural tube and epidermis are separate events. These studies demonstrate that NFPC and TAF1 function to maintain proper cell-cell interactions within the neural folds and suggest that NFPC and TAF1 participate in novel adhesive mechanisms that contribute to the final events of vertebrate neurulation.

Actins↗
PubMed1994

[Keratoconus in Mulvihill-Smith syndrome].

BACKGROUND: The Mulvihill-Smith syndrome consists of a large number of stigmata. A few of them are also seen in the LEOPARD syndrome. In both syndromes keratoconus has not yet been reported. PATIENT: We present a twenty-year-old male patient suffering from keratoconus in connection with a Mulvihill-Smith syndrome. A keratoplasty à chaud was done after perforation of the corneal ulcer. CONCLUSION: As a major complication corneal graft rejection is known after keratoplasty à chaud. However, in our patient immunological graft failure may be prevented by the T-cell defect.

Abnormalities, Multiple↗
PubMed1994

Multiple developmental defects in Engrailed-1 mutant mice: an early mid-hindbrain deletion and patterning defects in forelimbs and sternum.

During mouse development, the homeobox-containing gene En-1 is specifically expressed across the mid-hindbrain junction, the ventral ectoderm of the limb buds, and in regions of the hindbrain, spinal cord, somites and somite-derived tissues. To address the function of En-1 during embryogenesis, we have generated mice homozygous for a targeted deletion of the En-1 homeobox. En-1 mutant mice died shortly after birth and exhibited multiple developmental defects. In the brains of newborn mutants, most of the colliculi and cerebellum were missing and the third and fourth cranial nerves were absent. A deletion of midhindbrain tissue was observed as early as 9.5 days of embryonic development and the phenotype resembles that previously reported for Wnt-1 mutant mice. In addition, patterning of the forelimb paws and sternum was disrupted, and the 13th ribs were truncated. The results of these studies suggest a cell autonomous role for En-1 in generation and/or survival of mid-hindbrain precursor cells and also a non-cell autonomous role in signalling normal development of the limbs and possibly sternum.

Animals↗
PubMed1998

A case of probable autosomal recessive ectodermal dysplasia with corkscrew hairs and mental retardation in a family with tuberous sclerosis.

We describe a woman with a probable autosomal recessive ectodermal dysplasia with corkscrew hairs and mental retardation in a family with tuberous sclerosis. Other findings included syndactyly, typical facies, dental abnormalities, dermatoglyphic hypoplasia, epidermal ridge sweat pore count slightly below normal, and keratosis pilaris. Clinical studies and genetic analysis excluded the diagnosis of tuberous sclerosis in our patient. We conclude that she has ectodermal dysplasia associated with mental retardation. This association has been described previously; it suggests the possible interrelationship of a community of ectodermal dysplasia syndromes with a distinctive structural hair abnormality (pili torti et canaliculi), variable midfacial malformations, limb defects, and other features such as mental retardation. The similarity of our patient to that described by Whiting et al. and Abramovits-Ackerman et al. suggests the autonomy of this syndrome.

Adult↗
PubMed1984

Studies on "Repeated Epilation" mouse mutant embryos: II. Development of limb, tail, and skin defects.

The present paper reports the development of limbs, tail, and skin abnormalities in homozygous Repeated Epilation (Er/Er) mouse embryos. Defects can first be observed on day 13 and become fully expressed at 18-19 days of gestation (vaginal plug = day 1 of gestation). In 13-day-old embryos, the apical ectodermal ridge and some areas of the limb epidermis are unusually thickened. A similar hyperplasia affects the tail tip and the flank epidermis. Limb defects are located in the autopod. Both pairs of footplates are shortened and deformed; no separation occurs between the digits. Only the phalanges are involved; they may be joined together either by soft tissues or by cartilage. Hypophalangy affects the most distal phalanges. Nails are missing or poorly developed. At stage 13, the tail tip is bent over the dorsal side and becomes twisted; at later stages, the tail appears shortened. From the 14-day stage onwards, there is a progressive fusion between the limb, the body, and/or the tail epidermis. The embryological analysis of the abnormalities indicates that the thickened and rigid epidermis impedes the normal growth of the limb buds and of the tail. Our observations suggest that limb and tail defects observed in mice homozygous for the Repeated Epilation mutation may be secondary to primary changes occurring in the epidermis. Some malformations described in this paper closely resemble those observed in sm/sm (syndactylism) and pf (pupoid fetus) mouse embryos.

Animals↗
PubMed1995

Mutation of a type II keratin gene (K6a) in pachyonychia congenita.

Pachyonychia congenita (PC) is a rare autosomal dominant condition characterized by multiple ectodermal abnormalities. Patients with Jadassohn-Lewandowsky Syndrome (MIM #167200; PC-1) have nail defects (onchyogryposis), palmoplantar hyperkeratosis, follicular hyperkeratosis and oral leukokeratosis. Those with the rarer Jackson-Lawler Syndrome (MIM #167210; PC-2) lack oral involvement but have natal teeth and cutaneous cysts. Ultra-structural studies have identified abnormal keratin tonofilaments and linkage to the keratin gene cluster on chromosome 17 has been found in PC families. Keratins are the major structural proteins of the epidermis and associated appendages and the nail, hair follicle, palm, sole and tongue are the main sites of constitutive K6, K16 and K17 expression. Furthermore, mutations in K16 and K17 have recently been identified in some PC patients. Although we did not detect K16 or K17 mutations in PC families from Slovenia, we have found a heterozygous deletion in a K6 isoform (K6a) in the affected members of one family. This 3 bp deletion (AAC) in exon 1 of K6a removes a highly conserved asparagine residue (delta N170) from position 8 of the 1A helical domain (delta N8). This is the first K6a mutation to be described and this heterozygous K6a deletion is sufficient to explain the pathology observed in this PC-1 family.

Amino Acid Sequence↗
PubMed2003

Characterization of regulatory elements and methylation pattern of the autoimmune regulator (AIRE) promoter.

Defects in the AIRE gene cause a monogenic autoimmune syndrome APECED (autoimmune polyendocrinopathy candidiasis ectodermal dystrophy), which is characterized by loss of self-tolerance to multiple organs. In concordance with its role in immune tolerance, AIRE is most strongly expressed in thymic epithelial cells and in cells of monocytic-dendritic lineage. The AIRE protein has been shown to function as a transcriptional regulator, however, the mechanisms regulating AIRE gene expression are not known. Here we have characterized the AIRE promoter region by identifying a minimal promoter region within 350 bp of the translation initiation codon. Electrophoretic mobility shift assays and transient transfections with mutated promoter constructs revealed a functional TATA box (-163 to -153) and binding sites for transcription complexes AP-1 (-307 to -296), NF-Y (-213 to -202), and Sp1 (-202 to -189). The presence of a 390-bp CpG island within the proximal promoter suggested that cytosine methylation has a role in transcriptional regulation of AIRE, which was supported by in vitro methylation experiments of promoter constructs. Sodium bisulfite sequencing showed a less methylated status of AIRE promoter in the thymic epithelial cell line TEC1A3 compared with HeLa and monocytic cells U937 and THP-1. Real-time PCR analysis showed that treatment with 5-aza-2'-deoxycytidine (5-azaCdR), a DNA methyltransferase inhibitor, up-regulated AIRE transcript levels in TEC1A3, U937, and HeLa cells and that even greater activations in TEC1A3 and U937 cells were observed using combined treatments with deacetylase inhibitor trichostatin A. These results suggest that AIRE gene expression is modulated through modifications in chromatin methylation and acetylation.

Base Sequence↗
PubMed2006

Handless, footless fetus.

We report a fetus with symmetrical terminal transverse limb deficiency. Two earlier reports described patients with similar defects. These patients resemble the animal models that result from the removal of apical ectodermal ridge.

Abnormalities, Multiple↗
PubMed2004

Gremlin-mediated BMP antagonism induces the epithelial-mesenchymal feedback signaling controlling metanephric kidney and limb organogenesis.

Epithelial-mesenchymal feedback signaling is the key to diverse organogenetic processes such as limb bud development and branching morphogenesis in kidney and lung rudiments. This study establishes that the BMP antagonist gremlin (Grem1) is essential to initiate these epithelial-mesenchymal signaling interactions during limb and metanephric kidney organogenesis. A Grem1 null mutation in the mouse generated by gene targeting causes neonatal lethality because of the lack of kidneys and lung septation defects. In early limb buds, mesenchymal Grem1 is required to establish a functional apical ectodermal ridge and the epithelial-mesenchymal feedback signaling that propagates the sonic hedgehog morphogen. Furthermore, Grem1-mediated BMP antagonism is essential to induce metanephric kidney development as initiation of ureter growth, branching and establishment of RET/GDNF feedback signaling are disrupted in Grem1-deficient embryos. As a consequence, the metanephric mesenchyme is eliminated by apoptosis, in the same way as the core mesenchymal cells of the limb bud.

Alleles↗
PubMed2002

Calmodulin-dependent protein kinase IV mediated antagonism of BMP signaling regulates lineage and survival of hematopoietic progenitors.

In the current study, we show that bone morphogenetic proteins (BMPs) play a role in hematopoiesis that is independent of their function in specifying ventral mesodermal fate. When BMP activity is upregulated or inhibited in Xenopus embryos hematopoietic precursors are specified properly but few mature erythrocytes are generated. Distinct cellular defects underlie this loss of erythrocytes: inhibition of BMP activity induces erythroid precursors to undergo apoptotic cell death, whereas constitutive activation of BMPs causes an increase in commitment of hematopoietic progenitors to myeloid differentiation and a concomitant decrease in erythrocytes that is not due to enhanced apoptosis. These blood defects are observed even when BMP activity is misregulated solely in non-hematopoietic (ectodermal) cells, demonstrating that BMPs generate extrinsic signals that regulate hematopoiesis independent of mesodermal patterning. Further analysis revealed that endogenous calmodulin-dependent protein kinase IV (CaM KIV) is required to negatively modulate hematopoietic functions of BMPs downstream of receptor activation. Our data are consistent with a model in which CaM KIV inhibits BMP signals by activating a substrate, possibly cAMP-response element-binding protein (CREB), that recruits limiting amounts of CREB binding protein (CBP) away from transcriptional complexes functioning downstream of BMPs.

Animals↗