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Czeschik J.C.,University of Duisburg - Essen | Voigt C.,University of Duisburg - Essen | Alanay Y.,Acibadem University | Albrecht B.,University of Duisburg - Essen | And 18 more authors.
Human Genetics | Year: 2013

Nager syndrome (MIM #154400) is the best-known preaxial acrofacial dysostosis, mainly characterized by craniofacial and preaxial limb anomalies. The craniofacial abnormalities mainly consist of downslanting palpebral fissures, malar hypoplasia, micrognathia, external ear anomalies, and cleft palate. The preaxial limb defects are characterized by radial and thumb hypoplasia or aplasia, duplication of thumbs and proximal radioulnar synostosis. Haploinsufficiency of SF3B4 (MIM*605593), which encodes SAP49, a component of the pre-mRNA spliceosomal complex, has recently been identified as the underlying cause of Nager syndrome. In our study, we performed exome sequencing in two and Sanger sequencing of SF3B4 in further ten previously unreported patients with the clinical diagnosis of Nager syndrome, including one familial case. We identified heterozygous SF3B4 mutations in seven out of twelve patients. Four of the seven mutations were shown to be de novo; in three individuals, DNA of both parents was not available. No familial mutations were discovered. Three mutations were nonsense, three were frameshift mutations and one T > C transition destroyed the translation start signal. In three of four SF3B4 negative families, EFTUD2 was analyzed, but no pathogenic variants were identified. Our results indicate that the SF3B4 gene is mutated in about half of the patients with the clinical diagnosis of Nager syndrome and further support genetic heterogeneity for this condition. © 2013 Springer-Verlag Berlin Heidelberg.

Harewood L.,Institute of Genetic and Molecular Medicine | Keeling J.W.,Royal Infirmary | Fantes J.A.,Institute of Genetic and Molecular Medicine | Opitz J.M.,University of Utah | Fitzpatrick D.R.,Institute of Genetic and Molecular Medicine
Clinical Dysmorphology | Year: 2010

We report a male fetus with symmetrical peromelic reduction of the upper limbs (missing distal, mesial and proximal elements) and symmetrical phocomelic reduction of the lower limbs (missing proximal and mesial elements) without other major malformations. We identified 11 previously reported cases with very similar features and have named this entity 'Crommelin-type' symmetrical tetramelic reduction deformity. Interphase fluorescence in-situ hybridization on isolated nuclei from paraffin-embedded tissue was used to map the breakpoints in a previously reported case with a de-novo t(2;12)(p25.1;q23.3). The 2p25.1 breakpoint disrupted ROCK2, encoding Rho-associated, coiled-coil-containing protein kinase. The 12q23.3 breakpoint maps 0-25 kb 5 of CMKLR1, encoding chemokine-like receptor 1.Homozygous loss-of-function of either gene causes no major limb effect in mouse embryos. However, Cmklr1 shows both site-specific and stage-specific expression in mouse limb buds, but no mutations were identified in CMKLR1 or a nearby putative cis-regulatory region in the new case. We cannot assign a specific genetic mechanism in the translocation case but developmental disregulation of gene expression at one, or both, breakpoints may provide an explanation for the phenotype. © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Rainger J.,Institute of Genetic and Molecular Medicine | Bengani H.,Institute of Genetic and Molecular Medicine | Campbell L.,Metabolic Section | Anderson E.,Institute of Genetic and Molecular Medicine | And 20 more authors.
Human Molecular Genetics | Year: 2012

Biallelic mutations in the gene encoding DHOdehase [dihydroorotate dehydrogenase (DHODH)], an enzyme required for de novo pyrimidine biosynthesis, have been identified as the cause of Miller (Genée-Weidemann or postaxial acrofacial dysostosis) syndrome (MIM 263750). We report compound heterozygous DHODH mutations in four additional families with typical Miller syndrome. Complementation in auxotrophic yeast demonstrated reduced pyrimidine synthesis and in vitro enzymatic analysis confirmed reduced DHOdehase activity in 11 disease-associated missense mutations, with 7 alleles showing discrepant activity between the assays. These discrepancies are partly explained by the domain structure of DHODH and suggest both assays are useful for interpretation of individual alleles. However, in all affected individuals, the genotype predicts that there should be significant residual DHOdehase activity. Urine samples obtained from two mutation-positive cases showed elevated levels of orotic acid (OA) but not dihydroorotate (DHO), an unexpected finding since these represent the product and the substrate of DHODH enzymatic activity, respectively. Screening of four unrelated cases with overlapping but atypical clinical features showed no mutations in either DHODH or the other de novo pyrimidine biosynthesis genes (CAD, UMPS), with these cases also showing normal levels of urinary OA and DHO. In situ analysis of mouse embryos showed Dhodh, Cad and Umps to be strongly expressed in the pharyngeal arch and limb bud, supporting a site- and stage-specific requirement for de novo pyrimidine synthesis. The developmental sensitivity to reduced pyrimidine synthesis capacity may reflect the requirement for an exceptional mitogenic response to growth factor signalling in the affected tissues. © The Author 2012. Published by Oxford University Press. All rights reserved.

Allanson J.,Childrens Hospital of Eastern Ontario | Smith A.,Ottawa Hospital Research Institute | Hare H.,Northern Regional Genetics Program | Albrecht B.,Institute For Humangenetik | And 18 more authors.
American Journal of Medical Genetics, Part A | Year: 2012

Nablus mask-like facial syndrome (NMLFS) has many distinctive phenotypic features, particularly tight glistening skin with reduced facial expression, blepharophimosis, telecanthus, bulky nasal tip, abnormal external ear architecture, upswept frontal hairline, and sparse eyebrows. Over the last few years, several individuals with NMLFS have been reported to have a microdeletion of 8q21.3q22.1, demonstrated by microarray analysis. The minimal overlapping region is 93.98-96.22Mb (hg19). Here we present clinical and microarray data from five singletons and two mother-child pairs who have heterozygous deletions significantly overlapping the region associated with NMLFS. Notably, while one mother and child were said to have mild tightening of facial skin, none of these individuals exhibited reduced facial expression or the classical facial phenotype of NMLFS. These findings indicate that deletion of the 8q21.3q22.1 region is necessary but not sufficient for development of the NMLFS. We discuss possible genetic mechanisms underlying the complex pattern of inheritance for this condition. © 2012 Wiley Periodicals, Inc.

Harewood L.,Institute of Genetic and Molecular Medicine | Harewood L.,University of Lausanne | Liu M.,University of Edinburgh | Keeling J.,Royal Infirmary | And 6 more authors.
PLoS ONE | Year: 2010

Background: Bilateral renal agenesis/hypoplasia/dysplasia (BRAHD) is a relatively common, lethal malformation in humans. Established clinical risk factors include maternal insulin dependent diabetes mellitus and male sex of the fetus. In the majority of cases, no specific etiology can be established, although teratogenic, syndromal and single gene causes can be assigned to some cases. Methodology/Principal Findings: 45 unrelated fetuses, stillbirths or infants with lethal BRAHD were ascertained through a single regional paediatric pathology service (male:female 34:11 or 3.1:1). The previously reported phenotypic overlaps with VACTERL, caudal dysgenesis, hemifacial microsomia and Mü llerian defects were confirmed. A new finding is that 16/45 (35.6%; m:f 13:3 or 4.3:1) BRAHD cases had one or more extrarenal malformations indicative of a disoder of laterality determination including; incomplete lobulation of right lung (seven cases), malrotation of the gut (seven cases) and persistence of the left superior vena cava (five cases). One such case with multiple laterality defects and sirelomelia was found to have a de novo apparently balanced reciprocal translocation 46,XY,t(2;6)(p22.3;q12). Translocation breakpoint mapping was performed by interphase fluorescent in-situ hybridization (FISH) using nuclei extracted from archival tissue sections in both this case and an isolated bilateral renal agenesis case associated with a de novo 46,XY,t(1;2)(q41;p25.3). Both t(2;6) breakpoints mapped to gene-free regions with no strong evidence of cis-regulatory potential. Ten genes localized within 500 kb of the t(1;2) breakpoints. Wholemount in-situ expression analyses of the mouse orthologs of these genes in embryonic mouse kidneys showed strong expression of Esrrg, encoding a nuclear steroid hormone receptor. Immunohistochemical analysis showed that Esrrg was restricted to proximal ductal tissue within the embryonic kidney. Conclusions/Significance: The previously unreported association of BRAHD with laterality defects suggests that renal agenesis may share a common etiology with heterotaxy in some cases. Translocation breakpoint mapping identified ESRRG as a plausible candidate gene for BRAHD. © 2010 Harewood et al.

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