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PubMed1980

A new familial syndrome of 46,XY gonadal dysgenesis with anomalies of ectodermal and mesodermal structures.

Two 46,XY phenotypic female siblings, aged 1 1/2 and 8 1/2 years, have peculiar facies, cardiac, renal, musculoskeletal, and ectodermal anomalies, short stature, streak gonads, and mild developmental delay. Previous reported cases of 46,XY gonadal dysgenesis have not had major associated malformations. These children present a new constellation of anomalies unlike those seen in other types of gonadal dysgenesis and represent a new familial syndrome of 46,XY gonadal dysgenesis.

Abnormalities, Multiple↗
PubMed1992

Association of autosomal dominant cleft lip and palate and translocation 6p23;9q22.3.

Orofacial clefting (OFC) is genetically complex in that no single gene defect is responsible for all forms. We have identified a family who exhibit autosomal dominant orofacial clefting together with some features of ectodermal dysplasia. In this family there is concordance between these features and an apparently balanced translocation t(6;9)(p23;q22.3) which raises the possibility that a locus for one form of orofacial clefting may be located at one of the translocation breakpoints. Fluorescent in situ hybridization has shown that a candidate gene for OFC, which maps to distal 6p, is located on the derived chromosome 9 in affected individuals from this family. Further characterization of the translocation breakpoints and of their relationship with the candidate gene will determine whether a gene important for normal facial and/or ectodermal development is disrupted in this family.

Adult↗
PubMed2006

The genetic basis of tooth development and dental defects.

More than 300 genes have so far been associated with tooth development, mainly in mouse embryos. The majority of them are associated with conserved signaling pathways mediating cellular communication, in particular between epithelial and mesenchymal tissues. Necessary functions of many signals, receptors and transcription factors have been demonstrated in mice, and mutations causing dental defects in humans have been identified in several genes.

Animals↗
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↗
PubMed1999

Aplasia cutis congenita associated with fetus papyraceous.

This report describes a healthy infant born with an isolated, truncal cutis aplasia defect in association with a fetus papyraceous. Effective healing of the cutaneous defect occurred over the course of a month. A 2-year follow-up demonstrate stable wound coverage. This rare association of aplasia cutis congenita, with a fetus papyraceous points most likely to the vascular causation of the cutaneous defect.

Adult↗
PubMed2005

Severe defects in proliferation and differentiation of lens cells in Foxe3 null mice.

During mouse eye development, the correct formation of the lens occurs as a result of reciprocal interactions between the neuroectoderm that forms the retina and surface ectoderm that forms the lens. Although many transcription factors required for early lens development have been identified, the mechanism and genetic interactions mediated by them remain poorly understood. Foxe3 encodes a winged helix-forkhead transcription factor that is initially expressed in the developing brain and in the lens placode and later restricted exclusively to the anterior lens epithelium. Here, we show that targeted disruption of Foxe3 results in abnormal development of the eye. Cells of the anterior lens epithelium show a decreased rate of proliferation, resulting in a smaller than normal lens. The anterior lens epithelium does not properly separate from the cornea and frequently forms an unusual, multilayered tissue. Because of the abnormal differentiation, lens fiber cells do not form properly, and the morphogenesis of the lens is greatly affected. The abnormally differentiated lens cells remain irregular in shape, and the lens becomes vacuolated. The defects in lens development correlate with changes in the expression of growth and differentiation factor genes, including DNase II-like acid DNase, Prox1, p57, and PDGFalpha receptor. As a result of abnormal lens development, the cornea and the retina are also affected. While Foxe3 is also expressed in a distinct region of the embryonic brain, we have not observed abnormal development of the brain in Foxe3(-/-) animals.

Animals↗
PubMed1999

Function of Rieger syndrome gene in left-right asymmetry and craniofacial development.

Rieger syndrome, an autosomal dominant disorder, includes ocular, craniofacial and umbilical abnormalities. The pitx2 homeobox gene, which is mutated in Rieger syndrome, has been proposed to be the effector molecule interpreting left-right axial information from the early embryonic trunk to each organ. Here we have used gene targeting in mice to generate a loss-of-function allele that would be predicted to result in organ randomization or isomerization. Although pitx2-/- embryos had abnormal cardiac morphogenesis, mutant hearts looped in the normal direction. Pitx2-/- embryos had correctly oriented, but arrested, embryonic rotation and right pulmonary isomerism. They also had defective development of the mandibular and maxillary facial prominences, regression of the stomodeum and arrested tooth development. Fgf8 expression was absent, and Bmp4 expression was expanded in the branchial-arch ectoderm. These data reveal a critical role for pitx2 in left-right asymmetry but indicate that pitx2 may function at an intermediate step in cardiac morphogenesis and embryonic rotation.

Abnormalities, Multiple↗
PubMed2000

Genetic and embryological approaches to studies of neural tube defects: a critical review. NTD Collaborative Group.

Experimental embryological models have suggested that the morphology and quantity of neural tube defects may be governed by their position along the anteroposterior axis of the embryo. Inductive interactions and genetic regulation during axis development may play a role in the patterning of neural tube defects. A major challenge in the study of human neural tube defects is determining whether the spectrum of developmental neural tube anomalies found in individuals and their families mirror experimental models and are regulated by similar processes. We have found that the various neural tube defect phenotypes can be clustered according to their position along the anteroposterior axis. The findings correlate well to the pattern of early genes expression, inductive models of the embryonic axis, and mutant NTD animal models. We suggest that NTD should be studied by their location along the anteroposterior axis and that specific mutant genes may be identified by the observed pattern of NTD in an individual or a family.

Animals↗
PubMed2005

The range of defects associated with nuclear factor kappaB essential modulator.

PURPOSE OF REVIEW: Impaired ability to signal and activate specific gene transcription through nuclear factor kappaB (NFkappaB) has been directly linked to immunodeficiency. Hypomorphic mutations in the gene encoding NFkappaB essential modulator (NEMO), located on the X chromosome, impair NFkappaB function and lead to ectodermal dysplasia with immunodeficiency (ED-ID) with increased susceptibility to pyogenic bacteria, viruses and nonpathogenic mycobacterial infections. This is due to impaired, but not abolished, response to a variety of stimuli including Toll-like receptor agonists. Alternatively, loss-of-function (amorphic) mutations in the same gene lead to incontinentia pigmenti. The purpose of this review is to explore the range of immunologic defects associated with mutations in NEMO, a key regulatory molecule in the NFkappaB pathway. RECENT FINDINGS: In addition to the discovery of X-linked recessive hypomorphic mutations in NEMO as the cause of anhidrotic ED-ID, autosomal-dominant hypermorphic mutations in inhibitor of NFkappaB (IkappaB) alpha have been described recently. In addition, a better understanding of genotype-phenotype correlation in ED-ID patients is evolving. SUMMARY: ED-ID is a combined, variable but profound immunodeficiency characterized by susceptibility to pyogenic bacteria and mycobacterial infection. Understanding the features of particular NEMO mutations will provide insight into the role of this gene and will help define the crucial role of the function and regulation of NFkappaB in the immune response.

Animals↗
PubMed2002

The mouse polydactylous mutation, luxate (lx), causes anterior shift of the anteroposterior border in the developing hindlimb bud.

Pattern formation along the anterior-posterior axis of the vertebrate limb is established upon activation of Sonic Hedgehog (SHH) in the zone of polarizing activity (ZPA). Since many mouse mutants with preaxial polydactyly show ectopic expression of Shh at the anterior margin of the limb buds, it has been thought to be a primary defect caused by these mutations. We show here that the mouse mutation luxate (lx) exhibits dose-dependent reduction in the size of the Fgf8 expression domain in the ectoderm from the initial stage of limb development. This aberration was independent of Fgf10 expression in the limb mesenchyme. Shh was induced in the mesenchyme underlying the posterior end of the Fgf8 expression domain, indicating an anterior shift of Shh expression in lx hindlimb buds. Prior to the ectopic induction of Shh, the expression domains of genes downstream from Shh, namely dHAND, Gli1, Ptc and Gre, which are normally expressed in posterior mesenchyme of limb buds, expanded anteriorly on the lx hindlimb buds. Conversely, the expression domains of anterior mesenchymal markers such as Gli3and Alx4 decreased in size. Thus, ectopic Shh is not a primary defect of the lx mutation. Rather, our results indicate that the lx mutation affects the positioning of the anteroposterior border in developing hindlimb buds.

Animals↗
PubMed1996

Clouston syndrome (hidrotic ectodermal dysplasia) is not linked to keratin gene clusters on chromosomes 12 and 17.

Clouston syndrome is an hidrotic form of ectodermal dysplasia, inherited as an autosomal dominant trait with high penetrance. The main features of the disorder are alopecia, severe dystrophy of the nails, and palmoplantar hyperkeratosis. A molecular abnormality of keratin has long been hypothesized to be the basic defect in this disorder. We have performed linkage analyses between the disorder and markers close to the keratin gene clusters on chromosomes 12 and 17 and have excluded linkage to these candidate regions in three apparently unrelated families. In addition, linkage has been excluded to four other candidate regions including 1q2l, 17q23-qter, 18q2l, and 2Oql2. These data indicate that Clouston syndrome is not due to a defect in keratin or in a subset of keratin-associated proteins.

Chromosome Mapping↗
PubMed2006

Bosma arhinia microphthalmia syndrome.

Bosma et al. [1981] delineated a syndrome affecting two unrelated males with severe hypoplasia of the nose and eyes, palatal abnormalities, deficient taste and smell, inguinal hernias, hypogonadotropic hypogonadism with cryptorchidism, and normal intelligence. Other patients with this syndrome have been reported as cases of arhinia with associated defects. During embryonic development, the nasal placodes form 28 days after conception shortly after the optic vesicles makes contact with the overlying surface ectoderm at 26-27 days, and both layers invaginate to form the eyes between 34 and 44 days. Mice with homozygous mutations of Pax6, manifest underdevelopment of ocular and nasal structures, and a network of developmentally regulated genes function downstream of Pax6 to form nasal, ocular, and pituitary structures. These genes represent candidate genes for this disorder, and familial recurrence of Bosma syndrome has been reported to occur. This report describes two sporadic unrelated cases of this rare syndrome and briefly reviews the findings in previously reported cases.

Abnormalities, Multiple↗
PubMed1997

Altered neural cell fates and medulloblastoma in mouse patched mutants.

The PATCHED (PTC) gene encodes a Sonic hedgehog (Shh) receptor and a tumor suppressor protein that is defective in basal cell nevus syndrome (BCNS). Functions of PTC were investigated by inactivating the mouse gene. Mice homozygous for the ptc mutation died during embryogenesis and were found to have open and overgrown neural tubes. Two Shh target genes, ptc itself and Gli, were derepressed in the ectoderm and mesoderm but not in the endoderm. Shh targets that are, under normal conditions, transcribed ventrally were aberrantly expressed in dorsal and lateral neural tube cells. Thus Ptc appears to be essential for repression of genes that are locally activated by Shh. Mice heterozygous for the ptc mutation were larger than normal, and a subset of them developed hindlimb defects or cerebellar medulloblastomas, abnormalities also seen in BCNS patients.

Abnormalities, Multiple↗
PubMed1998

[Hereditary diseases with tooth anomalies and their causal genes].

In this review, we describe the current knowledge and the advances in research on human genes whose defect leads to dental anomalies. Recently, it was demonstrated that a missense mutation of a human homeobox MSX1 gene causes autosomal dominant agenesis of second premolars and third molars. X-linked anhidrotic ectodermal dysplasia (EDA), characterized by abnormal hair, teeth, and sweat glands, was demonstrated to be caused by a mutation in a novel transmembrane protein gene that is expressed in epithelial cells and in other adult and fetal tissues. The autosomal dominant Rieger syndrome (RS) manifests hypodontia, adontia, iridogoniodysgenesis and umbilical anomalies. Recently, a novel homeobox gene, RIEG, of Otx family was cloned as a causal gene of RS. The several mutations have been reported on the genes causing hypophosphatasia, which is characterized by defective mineralization of the skeletal and dental structures. An autosomal dominant dentinogenesis imperfecta (DI) is mostly associated with osteogenesis imperfecta (OI). Most patients with DI have mutations in either the COL1A1 or COL1A2 genes of type I collagen. Amelogenesis imperfecta (AI) is a diverse group of hereditary disorders characterized by a variety of developmental enamel defects including hypoplasia and hypomineralization, some of which have been revealed to be associated with defective amelogenin genes.

Alkaline Phosphatase↗
PubMed1996

The gene responsible for Clouston hidrotic ectodermal dysplasia maps to the pericentromeric region of chromosome 13q.

Hidrotic ectodermal dysplasia (HED), Clouston type, is an autosomal dominant skin disorder which is most common in the French-Canadian population and is characterized by hair defects, nail dystrophy and palmoplantar hyperkeratosis. Biophysical and biochemical studies conducted in HED suggested a molecular abnormality of keratins. We tested eight French-Canadian families segregating HED for linkage to microsatellite markers flanking the known keratin genes and were able to exclude linkage to these loci. Therefore, a genome-wide search for the HED gene was initiated. The first lod score above 3.00 was obtained with the marker D13S175 located in the pericentromeric region of chromosome 13q (Zmax = 8.12 at zero recombination). The cumulative lod scores were above 3.00 for six other markers in the region. A multipoint linkage analysis using the markers D13S175, D13S141 and D13S143 gave a maximum lod score of 11.12 at D13S141 with the one-lod-unit support interval spanning a 12.7 cM region which includes D13S175 and D13S141. Haplotype analysis allowed us to establish D13S143 as the telomeric flanking marker for the HED candidate region.

Centromere↗
PubMed2006

Novel gene ashwin functions in Xenopus cell survival and anteroposterior patterning.

The novel gene ashwin was isolated in a differential display screen for genes activated or up-regulated early in neural specification. ashwin is expressed maternally and zygotically, and it is up-regulated in the neural ectoderm after the midgastrula stage. It is expressed in the neural plate and later in the embryonic brain, eyes, and spinal cord. Overexpression of ashwin in whole embryos leads to anterior truncations and other defects. However, a second Organizer does not form, and the secondary axial structures may result from splitting of the Organizer, rather than axis duplication. Morpholino oligonucleotide-mediated reduction in ashwin expression leads to lethality or abnormalities in gastrulation, as well as significant apoptosis in midgastrula embryos. Apoptosis is also observed in midgastrula embryos overexpressing ashwin. Coexpression of ashwin with the bone morphogenetic protein-4 antagonist noggin has a synergistic effect on neural-specific gene expression in isolated animal cap ectoderm. Ashwin has no previously characterized domains, although two nuclear localization signals can be identified. Orthologues have been identified in the human, mouse, chicken, and pufferfish genomes. Our results suggest that ashwin regulates cell survival and anteroposterior patterning.

Amino Acid Sequence↗
PubMed2006

Regulation of early Xenopus development by ErbB signaling.

ErbB signaling has long been implicated in cancer formation and progression and is shown to regulate cell division, migration, and death during tumorigenesis. The functions of the ErbB pathway during early vertebrate embryogenesis, however, are not well understood. Here we report characterization of ErbB activities during early frog development. Gain-of-function analyses show that EGFR, ErbB2, and ErbB4 induce ectopic tumor-like cell mass that contains increased numbers of mitotic cells. Both the muscle and the neural markers are expressed in these ectopic protrusions. ErbBs also induce mesodermal markers in ectodermal explants. Loss-of-function studies using carboxyl terminal-truncated dominant-negative ErbB receptors demonstrate that blocking ErbB signals leads to defective gastrulation movements and malformation of the embryonic axis with a reduction in the head structures in early frog embryos. These data, together with the observation that ErbBs are expressed early during frog embryogenesis, suggest that ErbBs regulate cell proliferation, movements, and embryonic patterning during early Xenopus development.

Amino Acid Sequence↗