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1/58. X-linked myotubular myopathy with probable germline mosaicism.

    X-linked myotubular myopathy is a disorder characterized by severe neonatal hypotonia and respiratory insufficiency. The mutation of MTMI gene results in a defective production of myotubularin, which is responsible for the maturational arrest of muscle development. An identical mutation in the carrier mother and the diseased child establishes the inheritance. We report the disease in a neonate with a mutation on exon 6 of the MTMI gene. Surprisingly, the mother was healthy and did not carry this mutation, she is likely to have germline mosaicism.
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ranking = 1
keywords = defect
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2/58. X-linked thrombocytopenia caused by a mutation in the Wiskott-Aldrich syndrome (WAS) gene that disrupts interaction with the WAS protein (WASP)-interacting protein (WIP).

    OBJECTIVE: We studied two adult brothers with severe congenital thrombocytopenia in order to determine the genetic etiology of their inherited disorder. Despite the absence of eczema or immunodeficiency, a mutation of the Wiskott-Aldrich syndrome (WAS) gene was suspected because of the presence of microthrombocytes. MATERIALS AND methods: Peripheral blood was obtained for characterization of hematopoietic cells and megakaryocyte progenitors. The coding region of the WAS gene was fully sequenced, and expression of the wiskott-aldrich syndrome protein, WASP, was evaluated by immunoblotting. The ability of WASP to physically associate with the WASP-interacting protein, WIP, was tested by yeast and mammalian two-hybrid techniques. RESULTS: In addition to thrombocytopenia, our investigation revealed an increased frequency of peripheral megakaryocyte progenitors (CFU-Mk) and incomplete cytoplasmic maturation by electron microscopy. Sequencing the WAS gene revealed a single base mutation, resulting in substitution of proline for arginine 138 (i.e., Arg138Pro). immunoblotting demonstrated reduced expression of the mutant WAS protein, and we showed that the Arg138Pro mutation significantly, but incompletely, disrupts WASP-WIP interaction. CONCLUSIONS: In this pedigree, X-linked thrombocytopenia is caused by a rare mutation in the fourth exon of the WAS gene. WASP levels are reduced in lymphocyte cell lines derived from the affected individuals. Furthermore, the mutation significantly but incompletely disrupts WASP-WIP interaction, whereas substitution of alanine or glutamic acid residues at the same position does not. This raises the possibility that protein-protein interaction and WASP stability are related properties.
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ranking = 144.2990209815
keywords = congenita
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3/58. Hypohydrotic ectodermal dysplasia: an unusual presentation and management in an 11-year-old Xhosa boy.

    ectodermal dysplasia (ED) is an inherited disorder in which two or more ectodermally derived structures fail to develop, or are abnormal in development. Hypohydrotic ectodermal dysplasia (HED) or Christ-Siemens-Touraine syndrome, is an X-linked recessive syndrome with an incidence of 1/10,000 to 1/100,000 births. Because of its X-linked inheritance pattern, it is more common in males. HED is characterised by hypohydrosis (diminished perspiration), hypotrichosis (decreased amount of hair) and microdontia (small teeth), hypodontia (lack of development of one or more teeth) or adontia (total lack of tooth development). These patients present diagnostic and treatment challenges because of variable oral manifestations. This report describes an 11-year-old Xhosa boy, who was referred to the University Dental faculty by his general medical practitioner because of hypodontia. General facial features included: frontal bossing, a depressed nasal bridge, 'butterfly' pattern of eczema over the nasal bridge to the malar process of each cheek, thinned out hair, loss of vertical dimension of face and dry skin. Intra-oral examination revealed hypodontia with peg-shaped anterior teeth and diastemas. Radiological examination revealed no developing permanent teeth or tooth buds. diagnosis was confirmed by doing a sweat gland count. Management included oral hygiene instruction, fluoride treatments, construction of a partial lower denture and counselling about his condition with particular reference to the danger of hyperthermia and control of allergies.
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ranking = 50452.103504726
keywords = ectodermal dysplasia, dysplasia
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4/58. Missense mutation in a patient with X-linked dyskeratosis congenita.

    We report the case of a 40-year-old male patient with dyskeratosis congenita(DKC). Sequencing of the DKC1 gene revealed an inherited missense mutation in base 1050 (GC), changing methionine to isoleucine. This is the third description of a mutation in codon 350 (exon 11), changing a very well conserved amino acid in the pseudouridine synthase (PUA) domain of dyskerin.
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ranking = 721.49510490748
keywords = congenita
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5/58. A novel CACNA1F mutation in a french family with the incomplete type of X-linked congenital stationary night blindness.

    PURPOSE: To describe a French family with the incomplete type of X-linked congenital stationary night blindness (CSNB2) associated with a novel mutation in the retina-specific calcium channel alpha(1) subunit gene (CACNA1F). DESIGN: Interventional case report. methods: Two family members with a history of nonprogressive night blindness and subnormal visual acuity were clinically examined and the genotype determined by molecular genetic analysis. RESULT: Both patients had clinical manifestations characteristic of CSNB2. Electrophysiologically, we found a predominant reduction of the ERG B-wave in the maximal response. Both rod and cone function were subnormal, with the latter tending to be more attenuated. We identified a C deletion at nucleotide position 4548, resulting in a frameshift with a predicted premature termination at codon 1524. CONCLUSIONS: The clinical and genetic study of a novel mutation in the CACNA1F gene adds further support to the contention that CSNB2 represents a genetically distinct retinal disorder of a calcium channel.
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ranking = 721.49510490748
keywords = congenita
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6/58. Postmortem findings in the coffin-lowry syndrome.

    The coffin-lowry syndrome (CLS) is a congenital disorder that can be recognized by retarded growth and development, the characteristic appearance of the face and hands, and often by the typical deformities of the back and chest; there are many other anomalies. The history of the syndrome is reviewed, noting the x-linked semidominant pattern of inheritance, and two autopsies are presented and compared with the three autopsy reports that have been published previously. The five young patients died at ages between 18 to 28 years of advancing pneumonia, aspiration of food into the trachea, or postoperative complications. There were lesions or abnormalities in the heart, brain, lungs, liver, skeleton, kidneys, intestines, and other organs. Molecular geneticists have located the CLS gene or Rsk-2 gene at Xp22.2 and demonstrated that it works by influencing the activation of other genes. The "monopolygenic" pattern may help to explain the large number of seemingly unrelated abnormalities that make up this syndrome.
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ranking = 144.2990209815
keywords = congenita
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7/58. McLeod syndrome resulting from a novel XK mutation.

    McLeod Syndrome (MLS) is a rare X-linked disorder characterized by haemopoietic abnormalities and late-onset neurological and muscular defects. The McLeod blood group phenotype is typically associated with erythrocyte acanthocytosis, absence of the Kx antigen and reduced expression of Kell system antigens. MLS is caused by hemizygosity for mutations in the XK gene. We describe a patient with MLS who first showed symptoms in 1989 (aged 51 years). As the disease progressed, the patient developed a slight dementia, aggressive behaviour and choreatic movements. A cardiomyopathy was also diagnosed. An electroneuromyography showed neuropathic and myopathic changes. liver enzymes were elevated and a blood smear showed acanthocytes. MLS was confirmed by serological analysis of the Kell antigens. Analysis of red blood cells by flow cytometry revealed the patient and his grandson to have reduced Kell antigen expression. The patient's daughters had two populations of red cells, consistent with them being heterozygous for an XK0 allele. The molecular basis of MLS in this family is a novel mutation consisting of a 7453-bp deletion that includes exon 2 of the XK gene. This confirms that the patient's 7-year-old grandson, who is currently asymptomatic, also has the XK0 allele and is therefore likely to develop MLS.
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ranking = 1
keywords = defect
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8/58. A frameshift mutation of the ED1 gene in sibling cases with X-linked hypohidrotic ectodermal dysplasia.

    X-linked hypohidrotic ectodermal dysplasia (XLHED; MIM 305100) is characterized by the absence or hypoplasia of hair, teeth, and sweat glands. The ED1 gene was identified as a responsive gene for XLHED. The patients were 2 Japanese brothers. Both had the same mutation in exon 1 of the ED1 gene, i.e. C deletion at nucleotide 49, which induced a frameshift starting from amino acid 17 and made a stop codon at amino acid 56, encoding the transmembrane site. The mutation caused the extracellular domain of ectodysplasin A to be completely absent. Their mother had a heterozygous allele; she congenitally lacked 1 tooth, and incisors appeared conical in form.
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ranking = 50517.086806667
keywords = ectodermal dysplasia, congenita, dysplasia
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9/58. Unusual manifestations in X-linked amelogenesis imperfecta.

    This paper describes a female with X-linked amelogenesis imperfecta (XAI). This case is unusual in having taurodontism, pulpal calcifications, coronal defects prior to tooth eruption and unerupted teeth. These findings have been reported in some cases of autosomal dominant and autosomal recessive AI but have not previously been documented in XAI.
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ranking = 1
keywords = defect
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10/58. A new X-linked syndrome with agenesis of the corpus callosum, mental retardation, coloboma, micrognathia, and a mutation in the Alpha 4 gene at Xq13.

    We describe two brothers with a unique pattern of malformations that includes coloboma (iris, optic nerve), high forehead, severe retrognathia, mental retardation, and agenesis of the corpus callosum (ACC). Both boys have low-set cupped ears with sensorineural hearing loss, normal phallus, pectus excavatum, scoliosis, and short stature. One brother had choanal atresia and cardiac defects consisting of ventricular septal defect (VSD) and patent ductus arteriosus (PDA) which resolved spontaneously. Differential diagnosis between a number of clinical entities was considered, however, because ACC and the distinctive facial features were reminiscent of FG syndrome, dna was analyzed for markers linked to the FGS1 locus at Xq13-q21. Notably, the brothers were concordant for markers spanning this presumed FG region, and in both we have identified adjacent alterations (-57delT and T-55A) in the Alpha 4 gene located within this interval. Alpha 4 is a regulatory subunit of the major cellular phosphatase, PP2A, that has recently been shown to interact with MID1, the product of the gene mutated in X-linked Opitz GBBB syndrome. The double nucleotide change identified in this family was not observed in 410 control chromosomes, suggesting that it may be a pathogenetic change. Altered expression of Alpha 4, through either a change in translational efficiency, mRNA stability or splicing, could explain the clinical phenotype in these boys and the phenotypic overlap with Opitz GBBB syndrome.
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ranking = 2
keywords = defect
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