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Costello syndrome: report of six patients including one with an embryonal rhabdomyosarcoma.

UNLABELLED: Costello syndrome was first described in 1971. Besides papillomata, which were part of the initial description, patients tends to develop benign tumours of ectodermal origin. Aetiology is yet unknown but it is supposed to be the result of a sporadic dominant mutation. We report six patients with typical clinical findings and emphasise the importance of cardiac manifestations and the tendency to develop tumours. One patient developed an embryonal rhabdomyosarcoma, the occurrence of which has been reported twice before in patients with Costello syndrome. CONCLUSION: There might be a causal link between the development of rare tumours and this genetic disorder which may provide a new clue concerning the identification of the gene involved in Costello syndrome.

Cardiomyopathy, Hypertrophic↗

Protection from ethanol-induced limb malformations by the superoxide dismutase/catalase mimetic, EUK-134.

Based on previous in vitro studies that have illustrated prevention of ethanol-induced cell death by antioxidants, using an in vivo model, we have tested the anti-teratogenic potential of a potent synthetic superoxide dismutase plus catalase mimetic, EUK-134. The developing limb of C57BL/6J mice, which is sensitive to ethanol-induced reduction defects, served as the model system. On their ninth day of pregnancy, C57BL/6J mice were administered ethanol (two intraperitoneal doses of 2.9 g/kg given 4 h apart) alone or in combination with EUK-134 (two doses of 10 mg/kg). Pregnant control mice were similarly treated with either vehicle or EUK-134, alone. Within 15 h of the initial ethanol exposure, excessive apoptotic cell death was observed in the apical ectodermal ridge (AER) of the newly forming forelimb buds. Forelimb defects, including postaxial ectrodactyly, metacarpal, and ulnar deficiencies, occurred in 67.3% of the ethanol-exposed fetuses that were examined at 18 days of gestation. The right forelimbs were preferentially affected. No limb malformations were observed in control fetuses. Cell death in the AER of embryos concurrently exposed to ethanol and EUK-134 was notably reduced compared with that in embryos from ethanol-treated dams. Additionally, the antioxidant treatment reduced the incidence of forelimb malformations to 35.9%. This work illustrates that antioxidants can significantly improve the adverse developmental outcome that results from ethanol exposure in utero, diminishing the incidence and severity of major malformations that result from exposure to this important human teratogen.

Animals↗

Carcinoid tumor in a Meckel's diverticulum: hypothesis on mutual embryological origin.

Congenital defects presenting at an adult age are subject to diagnostic errors because of their relative rarity and often odd clinical presentation. We illustrate a 63-year-old male patient with multiple ileal carcinoid tumors along with a carcinoid tumor in Meckel's diverticulum. The Meckel's diverticulum is a congenital abnormality arising from a patent vitelline duct and is found at the anti-mesenteric side of the ileum. In the Meckel's diverticulum, ectopic tissue or neoplasms are sometimes found, which may lead to intussusception, hemorrhage, or inflammation. The carcinoid tumor is a neuroendocrine neoplasm originating from the neural crest and is diagnosed at virtually all ages. It may exhibit malignant behavior but generally has a mild clinical course. It is most often found in endodermally derived organs, especially the digestive and pulmonary tracts, and coexists frequently with malignant tumors, predominantly of endodermal origin such as colorectal carcinoma. The carcinoid tumor and Meckel's diverticulum are known to coincide, whereas the carcinoid is not really considered to be an embryologically determined defect. We hypothesize that both lesions are derived from local erroneous interaction among the neural crest and the endoderm.

Carcinoid Tumor↗

Expression of chicken fibroblast growth factor homologous factor (FHF)-1 and of differentially spliced isoforms of FHF-2 during development and involvement of FHF-2 in chicken limb development.

Members of the fibroblast growth factor (FGF) family have been identified as signaling molecules in a variety of developmental processes, including important roles in limb bud initiation, growth and patterning. This paper reports the cloning and characterization of the chicken orthologues of fibroblast growth factor homologous factors-1 and -2 (cFHF-1/cFGF-12 and cFHF-2/cFGF-13, respectively). We also describe the identification of a novel, conserved isoform of FHF-2 in chickens and mammals. This isoform arises by alternative splicing of the first exon of the FHF-2 gene and is predicted to encode a polypeptide with a distinct amino-terminus. Whole-mount in situ hybridization reveals restricted domains of expression of cFHF-1 and cFHF-2 in the developing neural tube, peripheral sensory ganglia and limb buds, and shows that the two cFHF-2 transcript isoforms are present in non-overlapping spatial distributions in the neural tube and adjacent structures. In the developing limbs, cFHF-1 is confined to the posterior mesoderm in an area that encompasses the zone of polarizing activity and cFHF-2 is confined to the distal anterior mesoderm in a region that largely overlaps the progress zone. Ectopic cFHF-2 expression is induced adjacent to grafts of cells expressing Sonic Hedgehog and the zone of cFHF-2 expression is expanded in talpid2 embryos. In the absence of the apical ectodermal ridge or in wingless or limbless mutant embryos, expression of cFHF-1 and cFHF-2 is lost from the limb bud. A role for cFHF-2 in the patterning and growth of skeletal elements is implied by the observation that engraftment of developing limb buds with QT6 cells expressing a cFHF-2 isoform that is normally expressed in the limb leads to a variety of morphological defects. Finally, we show that a secreted version of cFHF-2 activates the expression of HoxD13, HoxD11, Fgf-4 and BMP-2 ectopically, consistent with cFHF-2 playing a role in anterior-posterior patterning of the limb.

Alternative Splicing↗

p63 is essential for regenerative proliferation in limb, craniofacial and epithelial development.

The p63 gene, a homologue of the tumour-suppressor p53, is highly expressed in the basal or progenitor layers of many epithelial tissues. Here we report that mice homozygous for a disrupted p63 gene have major defects in their limb, craniofacial and epithelial development. p63 is expressed in the ectodermal surfaces of the limb buds, branchial arches and epidermal appendages, which are all sites of reciprocal signalling that direct morphogenetic patterning of the underlying mesoderm. The limb truncations are due to a failure to maintain the apical ectodermal ridge, a stratified epithelium, essential for limb development. The embryonic epidermis of p63-/- mice undergoes an unusual process of non-regenerative differentiation, culminating in a striking absence of all squamous epithelia and their derivatives, including mammary, lacrymal and salivary glands. Taken together, our results indicate that p63 is critical for maintaining the progenitor-cell populations that are necessary to sustain epithelial development and morphogenesis.

Animals↗

Twenty-four cases of the EEC syndrome: clinical presentation and management.

Twenty-four cases of EEC syndrome were identified as part of a nationwide study. Ectodermal dysplasia, by study definition, was present in all cases and hair and teeth were universally affected. Nail dysplasia was present in 19 subjects (79%) and the skin was affected in 21 (87%). The presence of hypohidrosis was not noted as a predominant feature in the syndrome and its occurrence appeared to depend on the presence of all other features. Distal limb defects from simple syndactyly to tetramelic cleft hand and foot were identified, including preaxial anomalies. Orofacial clefting was identified in 14 cases (58%) and lacrimal duct anomaly in 21 (87%). Significant clinical problems encountered were chiefly cosmetic or ophthalmological, but conductive deafness and genitourinary problems in some cases required surgical intervention. Altered self-image was also noted in some cases. Multidisciplinary management is necessary with the early involvement of the clinical geneticist. Developmentally, the EEC syndrome and related disorders represent disorders of ectodermal/mesodermal interaction. Candidate regions include 7q21.3, the "ectrodactyly" locus; other candidates include developmental genes implicated in the ectodermal/mesodermal interactive process.

Abnormalities, Multiple↗

Cardio-facio-cutaneous syndrome phenotype in an individual with an interstitial deletion of 12q: identification of a candidate region for CFC syndrome.

We report on a 19-month-old girl who presented with the phenotype of cardio-faciocutaneous (CFC) syndrome including characteristic minor facial anomalies, cardiac defect, ectodermal anomalies, and developmental delay. Cytogenetic analysis showed the presence of an interstitial deletion of one chromosome 12, del(12)(q21.2q22), confirmed by fluorescence in situ hybridization with chromosome band specific probes. Controversy exists as to whether CFC and Noonan syndrome (NS) are distinct disorders, a contiguous gene syndrome, or allelic variants. The identification of the del(12) in this patient, in a region distinct from the putative NS locus, supports the view that CFC is a genetically distinct condition from NS. In addition, this implicates the region 12q21.2-->4q22 as a candidate region for the gene(s) causing CFC syndrome.

Abnormalities, Multiple↗

Cellular analysis of limb development in the mouse mutant hypodactyly.

The limb defect in the mouse Hypodactyly (Hd) affects only the distal structures. Heterozygotes (Hd/+) lack all or part of the distal phalanx and the terminal claw of digit on the hindlimbs; mice homozygous (Hd/Hd) for the mutation have just one digit on each of the four limbs. Early limb development in the mutant appears normal and a change in morphology can only be detected later. Limb buds of Hd/+ and Hd/Hd embryos become reduced in width, with Hd/Hd buds becoming very pointed instead of rounded. This change in bud shape is correlated with an increase in cell death anteriorly in Hd/+ hindlimbs and both anteriorly and posteriorly in Hd/Hd fore- and hindlimb buds. The apical ectodermal ridge is very pronounced in pointed Hd/Hd limb buds. Mesenchyme cells from the Hd/Hd mutant in culture show a cell-autonomous change in behaviour and less cartilage differentiates.

Animals↗

Additional patient with del(12)(q21.2q22): further evidence for a candidate region for cardio-facio-cutaneous syndrome?

Cardio-facio-cutaneous (CFC) syndrome is characterized by a distinct facial appearance, cardiac defects, ectodermal anomalies and developmental delay. Recently, we reported a 19-month-old girl with phenotypic manifestations consistent with the CFC syndrome who had an interstitial deletion of the long arm of chromosome 12, del(12)(q21.2q22), implicating a possible locus for CFC syndrome. Here, we report an additional patient with a cytogenetically identical interstitial deletion: 47,XYY,del(12)(q21.2q22). To further characterize this deletion we used microarray-based comparative genomic hybridization (array CGH). Array CGH confirmed both the deletion and the second Y chromosome. The deletion on chromosome 12q spanned at least 14 Mb as indicated by the positions on the genome sequence of the 4 BAC clones included in the deletion. While the proband did not have the classic features of CFC, he had some dysmorphic craniofacial characteristics, ectodermal anomalies and moderate developmental delay which were suggestive of CFC syndrome; however, this patient did not have classical CFC. The phenotypic differences between the two del(12)(q21.2q22) patients may be due to variability in the expression of the syndrome, or this deletion may present as a syndrome with overlapping features. Alternatively, the phenotypic differences may result from discordance at the molecular level, which may yield a critical minimal region of deletion for CFC. The region 12q21.2 --> q22 remains a possible candidate region for CFC syndrome. Additional characterization of these and other CFC patients may confirm and further refine this candidate region.

Abnormalities, Multiple↗

Clinical and molecular analysis of nine families with Adams-Oliver syndrome.

Adams-Oliver syndrome (AOS) is defined by the combination of limb abnormalities and scalp defects, often accompanied by skull ossification defects. We studied nine families affected with AOS, eight of which have not been clinically described before. In our patients, scalp abnormalities were most often found, followed by limb and skull defects. The most common limb abnormalities appeared to be brachydactyly, syndactyly of toes 2 and 3 and hypoplastic toenails. Additional features observed were cutis marmorata telangiectatica congenita, cryptorchidism and cardiac abnormalities. In an attempt to identify the disease-causing mutations in our families, we selected two genes, ALX4 and MSX2, which were considered serious candidates based on their known function in skull and limb development. Mutation analysis of both genes, performed by direct sequencing, identified several polymorphisms, but no disease-causing mutations. Therefore, we can conclude that the AOS in our set of patients is not caused by mutations in ALX4 or MSX2.

DNA Mutational Analysis↗

[Aplasia cutis congenita in a newborn: etiopathogenic review and diagnostic approach].

Aplasia cutis congenita is a rare condition characterized by the congenital absence of epidermis, dermis and, in some cases, subcutaneous tissues. It was first described by Cordon in 1767 and more than 500 cases have been reported since, with an estimate incidence of 3 in 10,000 births. The lesions may occur on any body surface although localised agenesis of the scalp is the most frequent pattern. In approximately 20% of cases underlying bone defects are also found. Aplasia cutis congenita occurs as an isolated defect or with other associated anomalies. There is no unifying theory for the pathogenesis and large scalp defects present a management dilemma. We report a newborn with a large scalp defect in the midline at the vertex without associated malformations. There was no significant family history. Skull and extremities radiographs, chromosome analysis, cerebral and abdominal sonography were normal. Two methods of treatment were used: a conservative approach consisting of daily antiseptic dressing to allow scalp epithelialization improved conditions for secondary surgery at 30 days of life, closing the defect with local rotational flaps. The postoperative course was uneventful and an excellent cosmetic result was achieved.

Ectodermal Dysplasia↗

Aplasia cutis congenita in two siblings.

We report on two siblings with aplasia cutis congenita (ACC). This rare congenital malformation is characterized by a local defect of epidermis, dermis, and subcutaneous tissues occurring predominantly on the vertex of the scalp. Patient A (a boy) was born with a parietooccipital 4 x 4 cm scalp defect, that healed under conservative treatment with scar formation within three months. At the age of three years we started with serial excisions of the affected area. In patient B (a girl) two 1.5 x 1.5 cm midline scalp defects were noted at birth. After primary conservative treatment we performed an excision at the age of three years. Both children were born at term following normal pregnancy and delivery. Neither physical nor psychomotor retardation nor any other associated abnormality was found in these cases. Two younger brothers were born without any skin defects or other anomalies. There is no unifying theory on the pathogenesis of ACC. Traumatic, vascular, teratogenic, and genetic factors are discussed as initial steps in etiopathogenesis. In this family the occurrence of ACC in two siblings of either sex, with unaffected parents, may suggest an autosomal recessive mode of transmission. However autosomal dominant inheritance with germline mosaicism in one parent can not be excluded.

Child, Preschool↗

Novel compound heterozygous DOCK6 variants expand the mutational spectrum in prenatal diagnosis of Adams-Oliver syndrome 2.

BACKGROUND: Adams-Oliver syndrome (AOS) is a rare developmental disorder, and the DOCK6 gene is an identified AOS gene. This report highlights the prenatal diagnosis of AOS-2 by ultrasonography and genetic testing. METHODS: A growth-restricted fetus with bilateral ventriculomegaly, paraventricular calcifications, and ventricular septal defect underwent trio-whole-exome sequencing (trio-WES). Functional validation of the splice-altering variant was performed via minigene assays and protein structural modeling. RESULTS: Trio-WES revealed compound heterozygous DOCK6 variants: a paternal frameshift (c.3190_3191del; p. Leu1064Valfs60) and a maternal splice-site variant (c.3241-1G > T). Minigene assays demonstrated that c.3241-1G > T caused intron 26 retention (486 bp), introducing a premature termination codon (p. Val1081Glufs37). Structural modeling confirmed the loss of critical DHR2 domains in both truncated proteins. CONCLUSIONS: This study expands the mutational spectrum of DOCK6 and underscores the importance of combining prenatal imaging with functional genomics for early diagnosis of AOS2.

Adult↗

Carbon monoxide-induced axial skeletal dysmorphogenesis in the chick embryo.

BACKGROUND: Congenital axial skeletal defects affect two to three individuals per 1,000 live births. Without strong evidence for heritability, the cause is assumed to be multi-factorial. Carbon monoxide (CO), an increasingly prevalent environmental toxicant, is a potential environmental component in the etiology of these defects. The chick embryo is a useful model for the characterization and assessment of the mechanism(s) of action of basic developmental mechanisms. METHODS: We have determined a critical period and dose for CO teratogenicity and established a model of CO-induced axial skeletal dysmorphogenesis in the chick embryo. The resulting phenotypes reveal a spectrum of axial skeletal defects ranging from minor defects of the vertebral canal and inter-vertebral discs, to thoraco-lumbar scoliosis, to a tailless phenotype reminiscent of caudal dysgenesis syndrome. These axial skeletal defects have been related to earlier developmental defects in somitogenesis, including errors in segmentation and epithehalization and the expression of the somitic epithelialization factor, Paraxis. We have examined patterns of cell death and apoptosis in CO exposed chick embryos to assess the target tissue(s) involved in the teratogenicity of CO. RESULTS: With respect to the embryonic axis, the neural tube was found to be the most sensitive to CO-induced apoptosis, followed by the somitic mesoderm and Hensen's node. CONCLUSIONS: We hypothesize that the somitic defects and the resulting axial skeletal dysmorphogenesis are caused by disrupted neural tube or ectoderm functions related to somite formation and maintenance. We also hypothesize that CO-induced dysmorphogenesis at this critical period of somitogenesis is caused by the overabundance of CO acting endogenously as a cellular signal, while coincidentally exerting its influence as a toxicant of oxygen delivery or utilization.

Abnormalities, Drug-Induced↗

[Trichothiodystrophy: progresssive manifestations].

INTRODUCTION: Trichothiodystrophy is an autosomal recessive genodermatosis associating congenital dysplasia of the hair and neuroectodermal defects. Clinical expression is variable, although abnormalities are generally noted from birth. We report trichothiodystrophy in two brothers with the same phenotype who presented unusual progressive manifestations. OBSERVATIONS: Case 1: A six-year-old boy was seen for vesicular blisters due to photosensitization. Clinical examination showed dry, brittle, unmanageable hair, discrete koilonychia-type nail defects and an ichthyosiform state. The teeth were normal. In addition to psychomotor retardation, the patient presented a dysmorphic syndrome (poorly rimmed low-set ears; thick, triangular upper lip; scaphocephalic skull; short hands) and congenital bilateral cataract. The diagnosis of trichothiodystrophy was confirmed by a study of DNA repair after exposure to ultraviolet light. A repair defect was found similar to that in xeroderma pigmentosum group D. The patient experienced a worsening of psychomotor retardation and episodes of hair loss with edema and inflammation of the scalp resulting from infections. He also showed marked asthenia which resolved spontaneously within a few months. Case 2: The other brother, born as a collodion baby, presented the same clinical picture (cutaneous, exoskeletal, dysmorphic), including congenital bilateral cataract, photosensitivity and a parenchymatous blister-type pulmonary lesion probably secondary to bronchiectasis. The patient's cutaneous state progressively improved. He was seen at six years of age for an episode of inflammatory edema of the scalp with hair loss. Within six months, all of the hair redrew. The diagnosis of trichothiodystrophy was confirmed by a DNA repair defect after exposure to ultraviolet light. DISCUSSION: Trichothiodystrophy is clinically associated with photosensitivity (P), ichthyosis (I), dry, brittle hair (B), intellectual impairment (I), decreased fertility (D) and short stature (S), which accounts for the acronym PIBIDS or IBIDS syndrome, depending on whether photosensitivity is involved or not (actually in about 50 p. 100 of cases). Other possibly associated features include ungueal dysplasias, bilateral cataract, defective teeth, dysmorphic disorders predominant in the ears, neurologic disorders, pulmonary bronchiectasis and recurrent infections. The two cases presented here were thus very symptomatologically complete. The two problems of current concern are psychomotor retardation and temporary hair loss as a result of infections. The latter has only been described once in the literature. This case was similar to ours since photosensitivity was involved. Analysis of DNA repair also showed a defect after exposure to ultraviolet light similar to that found in xeroderma pigmentosum group D. Thus, episodic hair loss could be a symptom characteristic of forms of trichothiodystrophy with a DNA repair defect. However, the explanation for this hair loss is not known. Other ectodermal dysplasias can be complicated by hair loss with superinfection, such as AEC syndrome (ankyloblepharon, ectodermal dysplasia, cleft palate).

Abnormalities, Multiple↗

Cloning of Tabby, the murine homolog of the human EDA gene: evidence for a membrane-associated protein with a short collagenous domain.

X-Linked hypohidrotic ectodermal dysplasia (XLHED) is a human congenital disorder resulting in abnormal tooth, hair and sweat gland development. A candidate gene for the disorder has been cloned, but the function and full size of its putative protein product is unclear. We have identified a candidate cDNA for the mouse Tabby gene (Ta), which, based on phenotype and syntenic mapping, is postulated to represent the analogous murine disorder. Mutations have been identified in three different Ta alleles and Northern analysis indicates that the gene is expressed at increasing levels during embryogenesis (11-17 days p.c.), the period when affected structures develop. The putative protein product encoded by exon 1 is highly homologous (87% identical) to the predicted EDA protein product (135 amino acids), including the presence of a single transmembrane domain. However, the murine cDNA also encodes an additional 246 amino acids, which contains a short collagenous domain (Gly-X-Y)19. This predicted structure is similar to a number of membrane-associated proteins with either single or multiple collagenous domains in their extracellular C-terminal regions. Since mutations can only be identified in 10-15% of families with XLHED, it is likely that additional homologous exons exist for the human EDA gene. Hybridization of YACs from the EDA region with the Ta cDNA support this hypothesis. The predicted extracellular collagenous domain of this membrane protein may play a key role in epithelial-mesenchymal interactions, defects of which are thought to underlie the Ta/XLHED phenotype.

Amino Acid Sequence↗

Limb mammary syndrome: a new genetic disorder with mammary hypoplasia, ectrodactyly, and other Hand/Foot anomalies maps to human chromosome 3q27.

We report on a large Dutch family with a syndrome characterized by severe hand and/or foot anomalies, and hypoplasia/aplasia of the mammary gland and nipple. Less frequent findings include lacrimal-duct atresia, nail dysplasia, hypohydrosis, hypodontia, and cleft palate with or without bifid uvula. This combination of symptoms has not been reported previously, although there is overlap with the ulnar mammary syndrome (UMS) and with ectrodactyly, ectodermal dysplasia, and clefting syndrome. Allelism with UMS and other related syndromes was excluded by linkage studies with markers from the relevant chromosomal regions. A genomewide screening with polymorphic markers allowed the localization of the genetic defect to the subtelomeric region of chromosome 3q. Haplotype analysis reduced the critical region to a 3-cM interval of chromosome 3q27. This chromosomal segment has not been implicated previously in disorders with defective development of limbs and/or mammary tissue. Therefore, we propose to call this apparently new disorder "limb mammary syndrome" (LMS). The SOX2 gene at 3q27 might be considered an excellent candidate gene for LMS because the corresponding protein stimulates expression of FGF4, an important signaling molecule during limb outgrowth and development. However, no mutations were found in the SOX2 open reading frame, thus excluding its involvement in LMS.

Abnormalities, Multiple↗

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↗