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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↗

Limb-body wall complex: a compound anomaly pattern in body-wall defects.

Our presentation of four cases demonstrates the essential features of limb-body wall complex (LBWC), representing a compound anomaly pattern in body-wall defects. The diagnosis of this entity is based on two of the three following characteristics: (1) exencephaly/encephalocele and facial clefts; (2) thoraco- and/or abdominoschisis; and (3) limb defects. A definite association with internal anomalies and severe kyphoscoliosis makes a more distinct concept of the pathogenesis reasonable. Limb-body wall malformations result from a malfunction of the ectodermal placodes involving the early embryonic folding process. The poor prognosis of LBWC calls for early antenatal diagnosis.

Abdominal Muscles↗

En1 and Wnt7a interact with Dkk1 during limb development in the mouse.

Wnt signaling plays an essential role in induction and development of the limb. Missing digits are one consequence of the reduced Wnt signaling in Wnt7a null mice, while extra digits result from excess Wnt signaling in mice null for the Wnt antagonist Dkk1. The extra digits and expanded apical ectodermal ridge (AER) of Dkk1-deficient mice closely resemble En1 null mice. To evaluate the in vivo interaction between En1 and the canonical Wnt signaling pathway, we generated double and triple mutants combining the hypomorphic doubleridge allele of Dkk1 with null alleles of En1 and Wnt7a. Reducing Dkk1 expression in Dkk1d/+Wnt7a-/- double mutants prevented digit loss, indicating that Wnt7a acts through the canonical pathway during limb development. Reducing Dkk1 levels in Dkk1d/dEn1-/- double mutants resulted in severe phenotypes not seen in either single mutant, including fused bones in the autopod, extensive defects of the zeugopod, and loss of the ischial bone. The subsequent elimination of Wnt7a in Dkk1d/dEn1-/-Wnt7a-/- triple mutants resulted in correction of most, but not all, of these defects. The failure of Wnt7a inactivation to completely correct the limb defects of Dkk1d/dEn1-/- double mutants indicates that Wnt7a is not the only gene regulated by En1 during development of the mouse limb.

Alleles↗

Ocular manifestations of keratitis-ichthyosis-deafness (KID) syndrome.

OBJECTIVE: Keratitis-ichthyosis-deafness (KID) syndrome is a rare congenital ectodermal dysplasia characterized by the association of hyperkeratotic skin lesions, moderate to profound sensorineural hearing loss and vascularizing keratitis. Mutations in the GJB2 gene coding for connexin 26, a component of gap junctions in epithelial cells, have been observed in several KID patients. Variable ocular manifestations of the disease in 3 patients with molecular genetically confirmed KID syndrome are reported. DESIGN: Retrospective case series. METHODS: Clinical examination and molecular genetic analysis for mutations in the GJB2 gene were performed in 3 patients with KID syndrome ages 5, 13, and 41 years. RESULTS: Visual acuity ranged from normal to severe visual loss. The ocular signs included loss of eyebrows and lashes, thickened and keratinized lids, trichiasis, recurrent corneal epithelial defects, superficial and deep corneal stromal vascularization with scarring, keratoconjunctivitis sicca, and, in one patient, presumed limbal insufficiency. Whereas ocular surface integrity could be maintained with artificial tears in one patient, and an epithelial defect healed under conservative treatment in the second patient, multiple surgical procedures including superficial keratectomies, limbal allograft transplantation with systemic immunosuppression, amniotic membrane transplantation, lateral tarsorrhaphies, and lamellar keratoplasty could not preserve useful vision in the third patient. CONCLUSIONS: KID syndrome may affect the ocular adnexae and surface with variable severity independent of the age of the patient. Lid abnormalities, corneal surface instability, limbal stem cell deficiency with resulting corneal complications, and dry eye are the main ocular manifestations.

Adolescent↗

Monodactylous splithand-splitfoot. A malformation occurring in three distinct genetic types.

Monodactyly is a sign of at least 3 different types of autosomal dominant ectrodactyly. In the first type only the 1st and the 5th or only the 5th toes are present on both feet. The trait is fully expressed in all affected children of patients. No skipping of a generation has been observed. Both parents of several affected children may be normal, or one parent may show minor manifestations only. Single strand mutation is suggested as an explanation of these exceptional cases. Monodactyly is seen less frequently in the second type, ectrodactyly, ectodermal dysplasia and cleft lip and palate (the EEC syndrome), than in the first type. The limb defects are more variable. The third type of ectrodactyly shows extreme intrafamilial variability, comprising various degrees of ectrodactyly, monodactyly and adactyly, defects of the ulna and/or of the tibia. Minor manifestations often occur in affected children of patients. Skipping of a generation is not uncommon.

Abnormalities, Multiple↗

Mirror image duplication of the hands and feet: report of a sporadic case with multiple congenital anomalies.

Mirror image duplication of the hands and feet is a rare entity. Based on 3 previous reports, findings include nasal abnormalities, dimelia of ulna and fibula, tibial hypoplasia and mirror image duplication of hands and feet. We report on a sporadic case in which mirror image duplication was associated with multiple congenital anomalies. Although these cases may represent variable expression of the same dominantly transmitted complex polysyndactyly syndrome, it is possible that mirror image duplication of the hands and feet is a manifestation common to a number of distinct clinical entities. During limb bud development, duplication and aberrant positioning of the zone of polarizing activity in relation to the apical ectodermal ridge may account for the anatomic abnormalities of the hands and feet in these patients.

Abnormalities, Multiple↗

Congenital scalp and calvarial deficiencies: principles for classification and surgical management.

Congenital defects of the scalp and skull present a challenge for care providers because of a combination of their rarity and the magnitude of potential morbidity. Recent advancements in autogenous and alloplastic cranioplasty and scalp reconstruction techniques argue for a comprehensive consideration of this problem. This article (1) reviews the causes of congenital scalp and calvarial defects; (2) proposes a classification system based on defect type, similar to the tumor-node-metastasis classification, in that defect location, defect size, and extent of neuromeningeal involvement are the critical variables; and (3) presents algorithms for care based on the defect classification. A set of management principles on which treatment plans can be based for these unique problems is provided.

Algorithms↗

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↗

The expanding panorama of split hand foot malformation.

The split hand/foot malformation is a developmental defect of the extremities resulting from errors in the initiation and maintenance of the apical ectodermal ridge. The phenotype is genetically heterogeneous, and it can be identified either as an isolated phenotypic manifestation or as a constituent component of a malformation syndrome. This overview describes the clinical phenotype, related animal models, and the evolving genetic heterogeneity of the malformation.

Abnormalities, Multiple↗

Muscle function and dysfunction in health and disease.

Skeletal muscles of the trunk and limbs developmentally originate from the cells of the dermomyotomal compartment of the somite. A wealth of knowledge has been accumulated with regard to understanding the molecular regulation of embryonic skeletal myogenesis. Myogenic induction is controlled through a complex series of spatiotemporal dependent signaling cascades. Secreted signaling molecules from surrounding structures not only initiate the myogenic program, but also influence proliferation and differentiation decisions. The proper coordination of these molecular events is thus critical for the formation of physiologically functional skeletal muscles. Hereditary congenital skeletal muscle defects arise due to genetics lesions in myogenic specific components. Understanding the mechanistic routes of congenital skeletal muscle disease therefore requires a comprehensive knowledge of the developmental system. Ultimately, the application of this knowledge will improve the diagnostic and therapeutic methodologies for such diseases. The aim of this review is to overview our current understanding of skeletal muscle development and associated human congenital diseases.

Animals↗

Hypertrichosis, atrophic skin, ectropion, and macrostomia (Barber-Say syndrome): report of a new case.

We report on a child, born to a consanguineous parents, who presented with a multiple congenital anomalies (MCA) pattern consisting of severe hypertrichosis, macrostomia, ectropion, and atrophic skin. To our knowledge this is the third case with this combination of defects. The two previous cases were reported by Barber et al. [Syndrome Identification VIII(1):6-9, 1982], and David et al. [Am J Med Genet 41:192-195, 1991].

Abnormalities, Multiple↗

[The Johanson-Blizzard syndrome].

A 17 year and 10 month old boy with Johanson-Blizzard syndrome is presented as a case report for the first time. Diagnosis has been established on the basis of craniofacial abnormalities: microcephalia, parietal skin and bone defects, sparse hair with frontal up sweep, alae nasi hypoplasia, irregular dentition and nasolacrimal fistula, with mental insufficiency, partial exocrine pancreatic insufficiency and low birth-weight and length, hypotonia and failure to thrive in infancy. Congenital cataract and hiatus sacralis apertus are additional signs that have never been described in the literature concerning Johanson-Blizzard syndrome.

Adolescent↗

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↗

Aplasia cutis congenita, skull defect, brain heterotopia, and intestinal lymphangiectasia.

We describe a female infant with a previously unreported combination of manifestations characterized by aplasia cutis, skull defect, brain heterotopia, mild congenital lymphedema, and intestinal lymphangiectasia. The association of intestinal lymphangiectasia and aplasia cutis, and the association of intestinal lymphangiectasia with brain heterotopia in the lymphedema-lymphangiectasia-mental retardation syndrome have been described in single reports. In one family, the association of cortical dysplasia and congenital lymphedema have been related to mutations in the RELN gene.

Abnormalities, Multiple↗

Early-stage developmental abnormalities induced by murine cytomegalovirus.

The onset of the effects of murine cytomegalovirus (MCMV) infection on an early stage of embryonic development (nine days) in a mouse model was studied with the aid of scanning electron microscopy. MCMV was injected into the endometrial lumina of pregnant mice at the time of implantation. The mice were later killed, and sites of embryonic implantation were examined. Compared with uninfected mice and mice inoculated with heat-inactivated virus, litter sizes were reduced, and the incidence of abnormal fetuses was significantly increased among MCMV-infected animals. Scanning electron microscopy also revealed maldeveloped cranial regions characterized by an unclosed neural tube and severely underdeveloped head. Ectodermal abnormalities, including poxlike formations and ballooning cells, were observed in several embryos. Thus, early cytomegalovirus infection may not only result in fetal loss, but may also interfere with the process of morphogenesis.

Animals↗

Mesodermal induction defect as a possible cause of ear malformations.

Deafness due to inner ear anomalies is rarely associated with malformations of the auricles. We describe two brothers with profound congenital sensorineural deafness, abnormal vestibular function, normal ossicles, and delayed motor development. Since the external and inner ear originate from distinctly separate structures, the embryogenesis of this malformation association is less clear than in the more common association of external and middle anomalies, where the latter two structures are derived from the first and second branchial arches. The combination of auricular and inner ear anomalies, with sparing of the middle ear structures, can be explained on the assumption that mesodermal induction is responsible for normal differentiation of both the otocyst and of the branchial arch ectoderm. A recessive mutant gene may lead to a deficiency of a mesodermal inducer substance of a target tissue receptor site. A similar mechanism may be involved in other multiple malformation syndromes, whereby a mutant gene acting during a specific period of organogenesis causes disruption of the normal induction-competence relationship.

Cell Differentiation↗

Hypospadias and urethral development.

PURPOSE: Hypospadias is a common congenital anomaly that may be treated with surgical reconstruction. In the majority of cases the etiology remains elusive. Although androgens are clearly critical for penile development, defects in androgen metabolism and/or the androgen receptor explain only a small subset of cases of hypospadias. Strategies are presented for understanding the etiology of hypospadias. MATERIALS AND METHODS: Current scientific reports on the etiology of hypospadias were reviewed, and the embryology and possible mechanisms of urethral and penile formation are presented. RESULTS: A new theory of glandular human urethral development via endodermal cellular differentiation is proposed to replace the classic explanation of ectodermal intrusion. CONCLUSIONS: Careful studies of penile and urethral development have led to a better understanding of genital embryology. Future areas of study, such as endocrine disrupters, mesenchymal-epithelial interactions and mechanisms of penile growth, are proposed to explain the etiology of hypospadias.

Animals↗

Wnt3a-/--like phenotype and limb deficiency in Lef1(-/-)Tcf1(-/-) mice.

Members of the LEF-1/TCF family of transcription factors have been implicated in the transduction of Wnt signals. However, targeted gene inactivations of Lef1, Tcf1, or Tcf4 in the mouse do not produce phenotypes that mimic any known Wnt mutation. Here we show that null mutations in both Lef1 and Tcf1, which are expressed in an overlapping pattern in the early mouse embryo, cause a severe defect in the differentiation of paraxial mesoderm and lead to the formation of additional neural tubes, phenotypes identical to those reported for Wnt3a-deficient mice. In addition, Lef1(-/-)Tcf1(-/-) embryos have defects in the formation of the placenta and in the development of limb buds, which fail both to express Fgf8 and to form an apical ectodermal ridge. Together, these data provide evidence for a redundant role of LEF-1 and TCF-1 in Wnt signaling during mouse development.

Animals↗