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PubMed1999

Synergistic activities of alpha3 and alpha6 integrins are required during apical ectodermal ridge formation and organogenesis in the mouse.

Integrins alpha6beta1 and alpha6beta4 are cell surface receptors for laminins. Integrin alpha6-null mice die at birth with severe skin blistering and defects in the cerebral cortex and in the retina. Integrin alpha3beta1 can associate with laminins and other ligands. Integrin alpha3-null mice also die at birth, with kidney and lung defects at late stages of development, and moderate skin blistering. To investigate possible overlapping functions between alpha3 and alpha6 integrins, we analyzed the phenotype of compound alpha3-/-/alpha6-/- mutant embryos. Double homozygous mutant embryos were growth-retarded and displayed several developmental defects not observed in the single mutant animals. First, limb abnormalities characterized by an absence of digit separation and the fusion of preskeletal elements were observed. Further analyses indicated a defect in the apical ectodermal ridge, an essential limb organizing center. In the double mutant, the ridge appeared flattened, and ridge cells did not show a columnar morphology. A strong reduction in ridge cell proliferation and alterations of the basal lamina underlying the ectoderm were observed. These results suggest that alpha3 and alpha6 integrins are required for the organization or compaction of presumptive apical ectodermal ridge cells into a distinct differentiated structure. Additional defects were present: an absence of neural tube closure, bilateral lung hypoplasia, and several abnormalities in the urogenital tract. Finally, an aggravation of brain and eye lamination defects was observed. The presence of novel phenotypes in double mutant embryos demonstrates the synergism between alpha3 and alpha6 integrins and their essential roles in multiple processes during embryogenesis.

Abnormalities, Multiple↗

PubMed2001

Fibroblast growth factor receptor 2 (Fgfr2) plays an important role in eyelid and skin formation and patterning.

Initiating as protruding ridges above and below the optic vesicle, the eyelids of mice grow across the eye and temporarily fuse in fetal life. Mutations of a number of genes disrupt this developmental process and result in a birth defect, "open-eyelids at birth." Here we show that a critical event for eyelid induction occurs at embryonic day 11.5 (E11.5) when the single cell-layered ectoderm in the presumptive eyelid territory increases proliferation and undergoes morphologic transition to form cube-shaped epithelial cells. Using embryos lacking the Fgfr2 Ig domain III (Fgfr2(DeltaIII/DeltaIII)) generated by tetraploid rescue and chimeric embryo formation approaches, we demonstrate that this event is controlled by Fgfr2 signals as the Fgfr2(DeltaIII/DeltaIII) mutation blocks these changes and results in embryos without eyelids. Fgfr2 and its ligands are differentially expressed in the ectoderm and underlying mesenchyme and function in a reciprocal interacting loop that specifies eyelid development. We also demonstrate that similar defects account for failure of skin formation at early stages. Interestingly, Fgfr2-independent skin formation occurs at E14.5 mutant embryos, resulting in much thinner, yet well-differentiated epidermis. Notably, mutant skin remains thin with decreased hair density after transplantation to wild-type recipients. These data demonstrate an essential role of Fgfr2 in eyelid and skin formation and patterning.

Animals↗

PubMed2000

Reconstruction of aplasia cutis congenita of the trunk in a newborn infant using acellular allogenic dermal graft and cultured epithelial autografts.

Aplasia cutis congenita, a congenital condition characterized by the absence of all skin layers, occurs mostly on the scalp, but may also involve the trunk and extremities. Conservative treatment using silver sulfadiazine with daily dressing change has been recommended to avoid donor site morbidity and operative risks to the neonate who may have other congenital defects. Others have proposed early surgical intervention to prevent problems associated with delayed wound healing. In this case of a newborn, the authors used an alternative therapy to avoid delayed wound healing and multiple surgical interventions. During one operative procedure, a 130-cm2 lesion on the trunk was covered with allogeneic dermis and cultured epithelial autografts (CEAs). After 2.5 weeks and with three additional applications of CEAs at bedside, 90% of the wound had healed. At 27 months, the grafted area was smooth, and pliable with normal skin texture.

Abdomen↗

PubMed2002

Surgical treatment of aplasia cutis congenita of the scalp associated with bilateral coronal synostosis.

Aplasia cutis congenita is a rare condition characterized by the congenital absence of skin. The authors report a case of aplasia cutis congenita of the scalp associated with bilateral coronal synostosis. Simultaneous fronto-orbital advancement and skull reconstruction for large defect at the fontanelle were performed in the initial operation. A tissue expander made it possible to resect most of the hairless scar and totally cover the reconstructed defect and skull. During the second stage, the residual hairless scar was completely covered with hair-bearing scalp by tissue expansion and the residual skull defects were successfully reconstructed with split calvarial bone grafting.

Alopecia↗

PubMed1999

Perlecan maintains the integrity of cartilage and some basement membranes.

Perlecan is a heparan sulfate proteoglycan that is expressed in all basement membranes (BMs), in cartilage, and several other mesenchymal tissues during development. Perlecan binds growth factors and interacts with various extracellular matrix proteins and cell adhesion molecules. Homozygous mice with a null mutation in the perlecan gene exhibit normal formation of BMs. However, BMs deteriorate in regions with increased mechanical stress such as the contracting myocardium and the expanding brain vesicles showing that perlecan is crucial for maintaining BM integrity. As a consequence, small clefts are formed in the cardiac muscle leading to blood leakage into the pericardial cavity and an arrest of heart function. The defects in the BM separating the brain from the adjacent mesenchyme caused invasion of brain tissue into the overlaying ectoderm leading to abnormal expansion of neuroepithelium, neuronal ectopias, and exencephaly. Finally, homozygotes developed a severe defect in cartilage, a tissue that lacks BMs. The chondrodysplasia is characterized by a reduction of the fibrillar collagen network, shortened collagen fibers, and elevated expression of cartilage extracellular matrix genes, suggesting that perlecan protects cartilage extracellular matrix from degradation.

Animals↗

PubMed2006

Aplasia cutis congenita of the scalp: therapeutic modalities.

Agenesis of scalp is an uncommon but well-recognized clinical entity. Congenital scalp and skull defects can be either obvious or occult; over 300 cases have been reported in literature. Aplasia cutis congenita (ACC) is recognized as a heterogeneous disorder, all characterized by focal absence of the epidermis, dermis and sometimes the calvarium and/or dura. We present a case of ACC in an infant whose mother was exposed to a teratogenic drug (Methimazole--an antithyroid drug) during pregnancy. This case report is presented to highlight the steps to successful management. Definitive full thickness scalp cover at the earliest avoids secondary infection, eschar formation and exsanguination.

Ectodermal Dysplasia↗

PubMed2006

Adams-Oliver syndrome: clinical description of a four-generation family and exclusion of five candidate genes.

We present a Belgian Adams-Oliver syndrome (AOS) family with 10 affected individuals over four generations, of which six were available for this study. Clinical symptoms observed in these patients were very variable as previously reported in other families and included large areas of alopecia on the vertex of the skull and serious limb reduction defects with agenesis of all toes of one foot. To identify the disease-causing gene, we sequenced the MSX1, CART1, P63 (P73L), RUNX2, and HOXD13 genes in this family and nine previously reported families, but no disease-causing mutations were found. Further investigation is ongoing in these families in order to identify the genetic cause of AOS.

DNA Mutational Analysis↗

PubMed1989

CHILD syndrome. Phenotypic dichotomy in eicosanoid metabolism and proliferative rates among cultured dermal fibroblasts.

Dermal fibroblasts from a patient with CHILD syndrome (an acronym for congenital hemidysplasia with ichthyosiform erythroderma and limb defects) were obtained and successfully maintained in culture. Fibroblasts from an area of chronically hyperkeratotic skin were compared with fibroblasts from the corresponding contralateral area of normal skin in regard to proliferative activity and to both unstimulated and stimulated generation of PGE2, an eicosanoid with documented effects on both epidermal cell and fibroblast function. Compared with the uninvolved skin fibroblasts, those from involved skin showed (a) a slower rate of proliferation, (b) a cyclical pattern of PGE2 synthesis, and (c) an approximately 20-fold greater synthesis of PGE2 in response to human purified IL-1, a cytokine known to be secreted by epidermal keratinocytes. Furthermore, we were able to demonstrate that the cyclical generation of PGE2 by the involved skin fibroblasts is responsible for their slower rate of growth when compared with the uninvolved skin fibroblasts. These data document a phenotypic dichotomy between the uninvolved and involved skin fibroblasts in CHILD syndrome that may be exploited to increase our understanding of the nature of dermal influences that may affect epidermal growth and differentiation.

Abnormalities, Multiple↗

PubMed1999

p63 is a p53 homologue required for limb and epidermal morphogenesis.

The p53 tumour suppressor is a transcription factor that regulates the progression of the cell through its cycle and cell death (apoptosis) in response to environmental stimuli such as DNA damage and hypoxia. Even though p53 modulates these critical cellular processes, mice that lack p53 are developmentally normal, suggesting that p53-related proteins might compensate for the functions of p53 during embryogenesis. Two p53 homologues, p63 and p73, are known and here we describe the function of p63 in vivo. Mice lacking p63 are born alive but have striking developmental defects. Their limbs are absent or truncated, defects that are caused by a failure of the apical ectodermal ridge to differentiate. The skin of p63-deficient mice does not progress past an early developmental stage: it lacks stratification and does not express differentiation markers. Structures dependent upon epidermal-mesenchymal interactions during embryonic development, such as hair follicles, teeth and mammary glands, are absent in p63-deficient mice. Thus, in contrast to p53, p63 is essential for several aspects of ectodermal differentiation during embryogenesis.

Animals↗

PubMed1993

Cardio-facio-cutaneous (CFC) syndrome: neurological features in two children.

Cardio-facio-cutaneous (CFC) syndrome consists of heart defects, a characteristic facial appearance, ectodermal abnormalities, growth retardation and developmental delay. The authors report two children with this condition, drawing particular attention to the neurological manifestations. The neurological features are neuro-opthalmological findings such as strabismus, ptosis and nystagmus, cortical atrophy, ventriculomegaly, mental retardation, seizures and hypotonia. These manifestations may allow differentiation of CFC from Noonan syndrome, which shares many of the physical features, but not these neurological features.

Abnormalities, Multiple↗

PubMed1980

The IVIC syndrome: a new autosomal dominant complex pleiotropic syndrome with radial ray hypoplasia, hearing impairment, external ophthalmoplegia, and thrombocytopenia.

The IVIC syndrome is an autosomal dominant condition affecting mainly the upper limbs. It is described from 19 living members of one family of mostly Caucasoid descent; it came to Venezuela from the Canary Islands 140 years ago. The new mutation appeared six generations ago. It has complete penetrance and wide expressivity for a radial ray defect which may vary from an almost normal thumb to a severely malformed upper limb. When present, the thumb has a long/slender metacarpal and a short distal phalanx, reflected in a typical metacarpophalangeal (MP) pattern profile. Anthropometry reveals delayed growth in the forearms, clavicles, and cranium during adolescence, and permanently in the spine; the maturation of the face, tibiae, and feet is normal. The radial carpal bones are always affected, some being still hypoplastic at advanced ages. Constant palmar dermatoglyphic anomalies are a high a-b ridge count, a distally placed or absent t triradius, and an increased frequency of patterns in the second interdigital area. Extraocular muscles are involved almost always, producing strabismus. Hearing is bilaterally impaired due to a mixed congenital loss, either total or partial. Mild thrombocytopenia and leukocytosis are present before the age of 50 years. There is neither associated ectodermal dysplasia nor heart involvement [except for occasional mild, incomplete right bundle branch block (IRBBB)]; imperforate anus occurs in about 10% of affected persons. The possible pathogenetic relationship to the thalidomide embryopathy and to the Holt-Oram syndrome, among others, is discussed.

Adolescent↗

PubMed2005

The shoelace method in congenital aplasia of the scalp and skull.

Aplasia cutis congenita (ACC) is an uncommon skin disorder characterised by the absence of some or all layers of the skin. It may involve any part of the body, but is most common in the scalp. Some scalp lesions are associated with a defect of the underlying skull or even dura. Small superficial lesions heal spontaneously. Options available for larger defects and those involving the skull include conservative management, skin grafts, composite grafts, local scalp or pericranial flaps, and free microvascular transplants. This case report presents a delayed primary closure of a scalp and skull defect with the shoelace method and a temporary skin graft. The method is simple, gives an excellent cosmetic result, and can be used in moderately sized defects, where a direct suture is not possible.

Diseases in Twins↗

PubMed2000

SOX14 is a candidate gene for limb defects associated with BPES and Möbius syndrome.

Members of the SOX gene family encode proteins with homology to the HMG box DNA-binding domain of SRY, the Y-linked testis-determining gene. SOX genes are expressed during embryogenesis and are involved in the development of a wide range of different tissues. Mutations in SRY, SOX9 and SOX10 have been shown to be responsible for XY sex reversal, campomelic dysplasia and Waardenburg-Hirschsprung disease, respectively. It is likely that mutations in other SOX genes are responsible for a variety of human genetic diseases. SOX14 has been identified from a human genomic library and the mouse and chicken sequences obtained by polymerase chain reaction amplification. The SOX14 amino acid sequence is highly conserved across these species, suggesting an important role for this protein in vertebrate development. SOX14 is expressed in the neural tube and apical ectodermal ridge of the developing chicken limb. This is the only SOX gene known to be expressed in the apical ectodermal ridge, a structure that directs outgrowth of the embryonic limb bud. Human SOX14 is localised to a 1.15-Mb yeast artificial chromosome on chromosome 3q23, close to loci for BPES (blepharophimosis, ptosis, epicanthus inversus syndrome) and Mobius syndrome. Although SOX14 maps outside these loci, its expression pattern and chromosomal localisation suggest that it is a candidate gene for the limb defects frequently associated with these syndromes.

Amino Acid Sequence↗

PubMed1987

Limb body wall complex: I. Pathogenesis.

Twenty-five fetuses with limb body wall complex (LBW complex) were evaluated. The diagnosis was based on two out of three of the following: exencephaly/encephalocele with facial clefts; thoraco- and/or abdominoschisis; and limb defect. Ninety-five percent (24/25) of the fetuses had associated internal structural defects. In 72% (18/25) the internal defects have been recognized as being secondary to vascular disruption. Concordance was not found between the side and location of the body wall defect versus the limb, internal, and cranial defects. In 85% there was evidence for persistence of the extraembryonic coelom by examination of the placenta. In this same group (85%) there was persistence of the ectodermal-amnion margin, with the amnion being continuous with the skin of the body wall defect. In 40% (10/25) there were tags and amniotic adhesions at other sites. There was no difference in the types or incidence of internal defects between those with and those without amniotic bands. The abnormalities in this collection and experimental animal models support vascular disruption during 4-6 weeks' gestation as an etiology for LBW complex. There is disruption and loss of existing tissues, persistence of embryonic structures, and secondary malformations. Persistence of the extraembryonic coelom may lead to the typical amniotic tags, ring constrictions, and adhesions seen in some specimens.

Abdominal Muscles↗

PubMed2001

Surgical treatment of aplasia cutis in the Adams-Oliver syndrome.

Aplasia cutis is one of the features of the Adams-Oliver syndrome, beside limb anomalies. Aplasia cutis, congenital absence of skin, is a lesion that usually presents over the vertex of the skull. Management of aplasia cutis depends on the size of the skin defect and the child's physical condition. Scalp defects larger than approximately 1 cm should be treated surgically. In patients with aplasia cutis, surgery should preferably be performed using rotation scalp flaps, and additional split skin grafts. The history of two babies with the Adams-Oliver syndrome is presented. In the Adams-Oliver syndrome, large rotation scalp flaps are not reliable due to the abnormal vascularity of the skin. Skin grafting is the safest way, preventing hemorrhage and infection, in the operative treatment of aplasia cutis in these babies.

Ectodermal Dysplasia↗

PubMed2000

Nasal encephaloceles.

Nasal encephaloceles can be divided into frontoethmoidal and basal encephaloceles. Both conditions are very rare, but frontoethmoidal encephaloceles show a relatively high incidence (1:5,000) in Southeast Asia. The pathogenesis of encephaloceles may be explained by a disturbance in separation of surface ectoderm (epithelial layer) and neurectoderm (nervous tissue) in the midline just after closure of the neural folds. It should be regarded as a 'late' neurulation defect taking place during the 4th gestational week. Apoptosis appears to be related to this separation process. Frontoethmoidal encephaloceles can be recognized as a facial mass covered with normal skin, while basal encephaloceles may cause nasal obstruction or symptoms related to herniation of basal structures. Diagnostic CT or MR imaging delineates the anatomy of the herniated mass. Therapy for frontoethmoidal encephaloceles consists in excision of the cele, watertight closure of the dural defect and reconstruction of the skull defect. Basal encephaloceles may harbour vital herniated structures which should be saved. Hydrocephalus should be dealt with first, followed by elective single-stage reconstructive surgery. The prognosis appears to be better for patients with frontoethmoidal encephaloceles than for patients with occipital or parietal encephaloceles, and it depends largely on the presence of additional congenital anomalies of the brain. The differential diagnosis of a nasal mass must include nasal glioma, dermoid cyst, and nasal polyp.

Child↗

PubMed2006

Aplasia cutis congenita (epitheliogenesis imperfecta) in swine: observations from a large breeding herd.

Epitheliogenesis imperfecta has been reported in several animal species, and its inheritance is suspected to be autosomal recessive. This term has been used to describe two different diseases, namely epidermolysis bullosa and aplasia cutis congenita, which are both grossly characterized by an absence of epidermis or mucosal epithelium and are most frequently reported on the distal limbs and oral cavity. Epitheliogenesis imperfecta has been described in swine, but the literature on the subject is scarce. To better characterize this condition, 70 piglets with congenital skin defects macroscopically compatible with epitheliogenesis imperfecta were examined. In all but 1 case, only 1 piglet per litter was affected. Of the affected piglets, 65 (93%) were male, suggesting a sex-related problem. More than half of the piglets had multiple skin lesions. All defects were located on the caudal half of the body, and none was found in the oral cavity. Most lesions were characterized by an absence of epidermis and part of the dermis and adnexae. Adnexal dysplasia was also observed at several sites, both with and without epitheliogenesis imperfecta, suggesting a developmental problem. Fluid-filled, congenital subcutaneous bullae were noted grossly on 7 piglets; their relationship, if any, with epitheliogenesis imperfecta remains unknown. As the term epitheliogenesis imperfecta has been used in cases of epidermolysis bullosa, the term aplasia cutis congenita seems to be more appropriate to describe these lesions in swine.

Animals↗

PubMed1998

Drosophila engrailed can substitute for mouse Engrailed1 function in mid-hindbrain, but not limb development.

The Engrailed-1 gene, En1, a murine homologue of the Drosophila homeobox gene engrailed (en), is required for midbrain and cerebellum development and dorsal/ventral patterning of the limbs. In Drosophila, en is involved in regulating a number of key patterning processes including segmentation of the epidermis. An important question is whether, during evolution, the biochemical properties of En proteins have been conserved, revealing a common underlying molecular mechanism to their diverse developmental activities. To address this question, we have replaced the coding sequences of En1 with Drosophila en. Mice expressing Drosophila en in place of En1 have a near complete rescue of the lethal En1 mutant brain defect and most skeletal abnormalities. In contrast, expression of Drosophila en in the embryonic limbs of En1 mutants does not lead to repression of Wnt7a in the embryonic ventral ectoderm or full rescue of the embryonic dorsal/ventral patterning defects. Furthermore, neither En2 nor en rescue the postnatal limb abnormalities that develop in rare En1 null mutants that survive. These studies demonstrate that the biochemical activity utilized in mouse to mediate brain development has been retained by Engrailed proteins across the phyla, and indicate that during evolution vertebrate En proteins have acquired two unique functions during embryonic and postnatal limb development and that only En1 can function postnatally.

Animals↗