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1.  Missense mutations in β-1,3-N-acetylglucosaminyltransferase 1 (B3GNT1) cause Walker–Warburg syndrome 
Human Molecular Genetics  2013;22(9):1746-1754.
Several known or putative glycosyltransferases are required for the synthesis of laminin-binding glycans on alpha-dystroglycan (αDG), including POMT1, POMT2, POMGnT1, LARGE, Fukutin, FKRP, ISPD and GTDC2. Mutations in these glycosyltransferase genes result in defective αDG glycosylation and reduced ligand binding by αDG causing a clinically heterogeneous group of congenital muscular dystrophies, commonly referred to as dystroglycanopathies. The most severe clinical form, Walker–Warburg syndrome (WWS), is characterized by congenital muscular dystrophy and severe neurological and ophthalmological defects. Here, we report two homozygous missense mutations in the β-1,3-N-acetylglucosaminyltransferase 1 (B3GNT1) gene in a family affected with WWS. Functional studies confirmed the pathogenicity of the mutations. First, expression of wild-type but not mutant B3GNT1 in human prostate cancer (PC3) cells led to increased levels of αDG glycosylation. Second, morpholino knockdown of the zebrafish b3gnt1 orthologue caused characteristic muscular defects and reduced αDG glycosylation. These functional studies identify an important role of B3GNT1 in the synthesis of the uncharacterized laminin-binding glycan of αDG and implicate B3GNT1 as a novel causative gene for WWS.
doi:10.1093/hmg/ddt021
PMCID: PMC3613162  PMID: 23359570
2.  Mutations in ISPD cause Walker-Warburg syndrome and defective glycosylation of α-dystroglycan 
Nature genetics  2012;44(5):581-585.
Walker-Warburg syndrome (WWS) is an autosomal recessive multisystem disorder characterized by complex eye and brain abnormalities with congenital muscular dystrophy (CMD) and aberrant α-dystroglycan (αDG) glycosylation. Here, we report mutations in the isoprenoid synthase domain-containing (ISPD) gene as the second most common cause of WWS. Bacterial IspD is a nucleotidyl transferase belonging to a large glycosyltransferase family, but its role in chordates has been obscure to date because this phylum does not have the corresponding non-mevalonate isoprenoid biosynthesis pathway. Knockdown of ispd in zebrafish recapitulates the human WWS phenotype with hydrocephalus, reduced eye size, muscle degeneration and hypoglycosylated αDG. These results implicate a role for ISPD in αDG glycosylation to maintain sarcolemma integrity in vertebrates.
doi:10.1038/ng.2253
PMCID: PMC3378661  PMID: 22522421
3.  Genome-Wide Copy Number Variation in Epilepsy: Novel Susceptibility Loci in Idiopathic Generalized and Focal Epilepsies 
PLoS Genetics  2010;6(5):e1000962.
Epilepsy is one of the most common neurological disorders in humans with a prevalence of 1% and a lifetime incidence of 3%. Several genes have been identified in rare autosomal dominant and severe sporadic forms of epilepsy, but the genetic cause is unknown in the vast majority of cases. Copy number variants (CNVs) are known to play an important role in the genetic etiology of many neurodevelopmental disorders, including intellectual disability (ID), autism, and schizophrenia. Genome-wide studies of copy number variation in epilepsy have not been performed. We have applied whole-genome oligonucleotide array comparative genomic hybridization to a cohort of 517 individuals with various idiopathic, non-lesional epilepsies. We detected one or more rare genic CNVs in 8.9% of affected individuals that are not present in 2,493 controls; five individuals had two rare CNVs. We identified CNVs in genes previously implicated in other neurodevelopmental disorders, including two deletions in AUTS2 and one deletion in CNTNAP2. Therefore, our findings indicate that rare CNVs are likely to contribute to a broad range of generalized and focal epilepsies. In addition, we find that 2.9% of patients carry deletions at 15q11.2, 15q13.3, or 16p13.11, genomic hotspots previously associated with ID, autism, or schizophrenia. In summary, our findings suggest common etiological factors for seemingly diverse diseases such as ID, autism, schizophrenia, and epilepsy.
Author Summary
Epilepsy, a common neurological disorder characterized by recurrent seizures, affects up to 3% of the population. In some cases, the epilepsy has a clear cause such as an abnormality in the brain or a head injury. However, in many cases there is no obvious cause. Numerous studies have shown that genetic factors are important in these types of epilepsy, but although several epilepsy genes are known, we can still only identify the genetic cause in a very small fraction of cases. In order to identify new genes that contribute to the genetic causes of epilepsy, we searched the human genome for deletions (missing copies) and duplications (extra copies) of genes in ∼500 patients with epilepsy that are not found in control individuals. Using this approach, we identified several large deletions that are important in at least 3% of epilepsy cases. Furthermore, we found new candidate genes, some of which are also thought to play a role in other related disorders such as autism and intellectual disability. These genes are candidates for further studies in patients with epilepsy.
doi:10.1371/journal.pgen.1000962
PMCID: PMC2873910  PMID: 20502679
4.  Duplication within the SEPT9 gene associated with a founder effect in North American families with hereditary neuralgic amyotrophy 
Human Molecular Genetics  2009;18(7):1200-1208.
Hereditary neuralgic amyotrophy (HNA) is an autosomal dominant disorder associated with recurrent episodes of focal neuropathy primarily affecting the brachial plexus. Point mutations in the SEPT9 gene have been previously identified as the molecular basis of HNA in some pedigrees. However in many families, including those from North America demonstrating a genetic founder haplotype, no sequence mutations have been detected. We report an intragenic 38 Kb SEPT9 duplication that is linked to HNA in 12 North American families that share the common founder haplotype. Analysis of the breakpoints showed that the duplication is identical in all pedigrees, and molecular analysis revealed that the duplication includes the 645 bp exon in which previous HNA mutations were found. The SEPT9 transcript variants that span this duplication contain two in-frame repeats of this exon, and immunoblotting demonstrates larger molecular weight SEPT9 protein isoforms. This exon also encodes for a majority of the SEPT9 N-terminal proline rich region suggesting that this region plays a role in the pathogenesis of HNA.
doi:10.1093/hmg/ddp014
PMCID: PMC2722193  PMID: 19139049
5.  Osteopoikilosis, short stature and mental retardation as key features of a new microdeletion syndrome on 12q14 
Journal of Medical Genetics  2007;44(4):264-268.
This report presents the detection of a heterozygous deletion at chromosome 12q14 in three unrelated patients with a similar phenotype consisting of mild mental retardation, failure to thrive in infancy, proportionate short stature and osteopoikilosis as the most characteristic features. In each case, this interstitial deletion was found using molecular karyotyping. The deletion occurred as a de novo event and varied between 3.44 and 6 megabases (Mb) in size with a 3.44 Mb common deleted region. The deleted interval was not flanked by low‐copy repeats or segmental duplications. It contains 13 RefSeq genes, including LEMD3, which was previously shown to be the causal gene for osteopoikilosis. The observation of osteopoikilosis lesions should facilitate recognition of this new microdeletion syndrome among children with failure to thrive, short stature and learning disabilities.
doi:10.1136/jmg.2006.047860
PMCID: PMC2598049  PMID: 17220210
osteopoikilosis; short stature; mental retardation;  HMGA2 ;  GRIP1
6.  Array comparative genomic hybridization and flow cytometry analysis of spontaneous abortions and mors in utero samples 
BMC Medical Genetics  2009;10:89.
Background
It is estimated that 10-15% of all clinically recognised pregnancies result in a spontaneous abortion or miscarriage. Previous studies have indicated that in up to 50% of first trimester miscarriages, chromosomal abnormalities can be identified. For several decades chromosome analysis has been the golden standard to detect these genomic imbalances. A major drawback of this method is the requirement of short term cultures of fetal cells. In this study we evaluated the combined use of array CGH and flow cytometry (FCM), for detection of chromosomal abnormalities, as an alternative for karyotyping.
Methods
In total 100 spontaneous abortions and mors in utero samples were investigated by karyotyping and array CGH in combination with FCM in order to compare the results for both methods.
Results
Chromosome analysis revealed 17 abnormal karyotypes whereas array CGH in combination with FCM identified 26 aberrations due to the increased test success rate. Karyotyping was unsuccessful in 28% of cases as compared to only two out of hundred samples with inconclusive results for combined array CGH and FCM analysis.
Conclusion
This study convincingly shows that array CGH analysis for detection of numerical and segmental imbalances in combination with flow cytometry for detection of ploidy status has a significant higher detection rate for chromosomal abnormalities as compared to karyotyping of miscarriages samples.
doi:10.1186/1471-2350-10-89
PMCID: PMC2753309  PMID: 19751515
7.  Recurrent Rearrangements of Chromosome 1q21.1 and Variable Pediatric Phenotypes 
Mefford, Heather C. | Sharp, Andrew J. | Baker, Carl | Itsara, Andy | Jiang, Zhaoshi | Buysse, Karen | Huang, Shuwen | Maloney, Viv K. | Crolla, John A. | Baralle, Diana | Collins, Amanda | Mercer, Catherine | Norga, Koen | de Ravel, Thomy | Devriendt, Koen | Bongers, Ernie M.H.F. | de Leeuw, Nicole | Reardon, William | Gimelli, Stefania | Bena, Frederique | Hennekam, Raoul C. | Male, Alison | Gaunt, Lorraine | Clayton-Smith, Jill | Simonic, Ingrid | Park, Soo Mi | Mehta, Sarju G. | Nik-Zainal, Serena | Woods, C. Geoffrey | Firth, Helen V. | Parkin, Georgina | Fichera, Marco | Reitano, Santina | Giudice, Mariangela Lo | Li, Kelly E. | Casuga, Iris | Broomer, Adam | Conrad, Bernard | Schwerzmann, Markus | Räber, Lorenz | Gallati, Sabina | Striano, Pasquale | Coppola, Antonietta | Tolmie, John L. | Tobias, Edward S. | Lilley, Chris | Armengol, Lluis | Spysschaert, Yves | Verloo, Patrick | De Coene, Anja | Goossens, Linde | Mortier, Geert | Speleman, Frank | van Binsbergen, Ellen | Nelen, Marcel R. | Hochstenbach, Ron | Poot, Martin | Gallagher, Louise | Gill, Michael | McClellan, Jon | King, Mary-Claire | Regan, Regina | Skinner, Cindy | Stevenson, Roger E. | Antonarakis, Stylianos E. | Chen, Caifu | Estivill, Xavier | Menten, Björn | Gimelli, Giorgio | Gribble, Susan | Schwartz, Stuart | Sutcliffe, James S. | Walsh, Tom | Knight, Samantha J.L. | Sebat, Jonathan | Romano, Corrado | Schwartz, Charles E. | Veltman, Joris A. | de Vries, Bert B.A. | Vermeesch, Joris R. | Barber, John C.K. | Willatt, Lionel | Tassabehji, May | Eichler, Evan E.
The New England journal of medicine  2008;359(16):1685-1699.
BACKGROUND
Duplications and deletions in the human genome can cause disease or predispose persons to disease. Advances in technologies to detect these changes allow for the routine identification of submicroscopic imbalances in large numbers of patients.
METHODS
We tested for the presence of microdeletions and microduplications at a specific region of chromosome 1q21.1 in two groups of patients with unexplained mental retardation, autism, or congenital anomalies and in unaffected persons.
RESULTS
We identified 25 persons with a recurrent 1.35-Mb deletion within 1q21.1 from screening 5218 patients. The microdeletions had arisen de novo in eight patients, were inherited from a mildly affected parent in three patients, were inherited from an apparently unaffected parent in six patients, and were of unknown inheritance in eight patients. The deletion was absent in a series of 4737 control persons (P = 1.1×10−7). We found considerable variability in the level of phenotypic expression of the microdeletion; phenotypes included mild-to-moderate mental retardation, microcephaly, cardiac abnormalities, and cataracts. The reciprocal duplication was enriched in the nine children with mental retardation or autism spectrum disorder and other variable features (P = 0.02). We identified three deletions and three duplications of the 1q21.1 region in an independent sample of 788 patients with mental retardation and congenital anomalies.
CONCLUSIONS
We have identified recurrent molecular lesions that elude syndromic classification and whose disease manifestations must be considered in a broader context of development as opposed to being assigned to a specific disease. Clinical diagnosis in patients with these lesions may be most readily achieved on the basis of genotype rather than phenotype.
doi:10.1056/NEJMoa0805384
PMCID: PMC2703742  PMID: 18784092
8.  Disease-Causing 7.4 kb Cis-Regulatory Deletion Disrupting Conserved Non-Coding Sequences and Their Interaction with the FOXL2 Promotor: Implications for Mutation Screening 
PLoS Genetics  2009;5(6):e1000522.
To date, the contribution of disrupted potentially cis-regulatory conserved non-coding sequences (CNCs) to human disease is most likely underestimated, as no systematic screens for putative deleterious variations in CNCs have been conducted. As a model for monogenic disease we studied the involvement of genetic changes of CNCs in the cis-regulatory domain of FOXL2 in blepharophimosis syndrome (BPES). Fifty-seven molecularly unsolved BPES patients underwent high-resolution copy number screening and targeted sequencing of CNCs. Apart from three larger distant deletions, a de novo deletion as small as 7.4 kb was found at 283 kb 5′ to FOXL2. The deletion appeared to be triggered by an H-DNA-induced double-stranded break (DSB). In addition, it disrupts a novel long non-coding RNA (ncRNA) PISRT1 and 8 CNCs. The regulatory potential of the deleted CNCs was substantiated by in vitro luciferase assays. Interestingly, Chromosome Conformation Capture (3C) of a 625 kb region surrounding FOXL2 in expressing cellular systems revealed physical interactions of three upstream fragments and the FOXL2 core promoter. Importantly, one of these contains the 7.4 kb deleted fragment. Overall, this study revealed the smallest distant deletion causing monogenic disease and impacts upon the concept of mutation screening in human disease and developmental disorders in particular.
Author Summary
Long-range genetic control is an inherent feature of genes harbouring a highly complex spatiotemporal expression pattern, requiring a combined action of multiple cis-regulatory elements such as promoters, enhancers, and silencers. Consequently, disruption of the long-range genetic control of a target gene by genomic rearrangements of regulatory elements may lead to aberrant gene transcription and disease. To date, the contribution of mutated regulatory elements to human disease has not been studied frequently. Here, we explored the contribution of genetic changes in potentially cis-regulatory elements of the FOXL2 gene in blepharophimosis syndrome (BPES), a developmental monogenic condition of the eyelids and ovaries. We identified a de novo very subtle deletion of 7.4 kb causing BPES. Moreover, we studied the functional capacities and chromosome conformation of the deleted region in FOXL2 expressing cellular systems. Interestingly, the chromosome conformation analysis demonstrated the close proximity of the 7.4 kb deleted fragment and two other conserved regions with the FOXL2 core promoter, and the necessity of their integrity for correct FOXL2 expression. Finally, our study revealed the smallest distant deletion causing monogenic disease and emphasized the importance of mutation screening of cis-regulatory elements in human genetic disease.
doi:10.1371/journal.pgen.1000522
PMCID: PMC2689649  PMID: 19543368
9.  Report of a female patient with mental retardation and tall stature due to a chromosomal rearrangement disrupting the OPHN1 gene on Xq12 
We report on a patient with mental retardation, seizures and tall stature with advanced bone age in whom a de novo apparently balanced chromosomal rearrangement 46,XX,t(X;9)(q12;p13.3) was identified. Using array CGH on flow-sorted derivative chromosomes (array painting) and subsequent FISH and qPCR analysis, we mapped and sequenced both breakpoints. The Xq12 breakpoint was located within the gene coding for oligophrenin 1 (OPHN1) whereas the 9p13.3 breakpoint was assigned to a non-coding segment within a gene dense region. Disruption of OPHN1 by the Xq12 breakpoint was considered the major cause of the abnormal phenotype observed in the proband.
doi:10.1016/j.ejmg.2007.07.003
PMCID: PMC2688819  PMID: 17845870
Translocation; OPHN1; Tall stature; Mental retardation
10.  arrayCGHbase: an analysis platform for comparative genomic hybridization microarrays 
BMC Bioinformatics  2005;6:124.
Background
The availability of the human genome sequence as well as the large number of physically accessible oligonucleotides, cDNA, and BAC clones across the entire genome has triggered and accelerated the use of several platforms for analysis of DNA copy number changes, amongst others microarray comparative genomic hybridization (arrayCGH). One of the challenges inherent to this new technology is the management and analysis of large numbers of data points generated in each individual experiment.
Results
We have developed arrayCGHbase, a comprehensive analysis platform for arrayCGH experiments consisting of a MIAME (Minimal Information About a Microarray Experiment) supportive database using MySQL underlying a data mining web tool, to store, analyze, interpret, compare, and visualize arrayCGH results in a uniform and user-friendly format. Following its flexible design, arrayCGHbase is compatible with all existing and forthcoming arrayCGH platforms. Data can be exported in a multitude of formats, including BED files to map copy number information on the genome using the Ensembl or UCSC genome browser.
Conclusion
ArrayCGHbase is a web based and platform independent arrayCGH data analysis tool, that allows users to access the analysis suite through the internet or a local intranet after installation on a private server. ArrayCGHbase is available at .
doi:10.1186/1471-2105-6-124
PMCID: PMC1173083  PMID: 15910681

Results 1-10 (10)