scholarly journals Approaches to gene mapping in complex disorders and their application in child psychiatry and psychology

2001 ◽  
Vol 179 (2) ◽  
pp. 122-128 ◽  
Author(s):  
Philip J. Asherson ◽  
Sarah Curran
Keyword(s):  
Reading Disability ◽  
Molecular Genetics ◽  
Molecular Mechanisms ◽  
Variable Number Tandem Repeat ◽  
Twin Studies ◽  
Variable Number ◽  
Chromosome 15 ◽  
Complex Disorders ◽  
Molecular Approaches ◽  
Genes And Environment

BackgroundTwin studies demonstrate the importance of genes and environment in the aetiology of childhood psychiatric and neurodevelopmental disorders. Advances in molecular genetics enable the identification of genes involved in complex disorders and enable the study of molecular mechanisms and gene–environment interactions.AimsTo review the role of molecular genetics studies in childhood behavioural and developmental traits.MethodMolecular approaches to complex disorders are reviewed, with examples from autism, reading disability and attention-deficit hyperactivity disorder (ADHD).ResultsThe most robust finding in ADHD is the association of a variable number tandem repeat polymorphism in exon 3 of the DRD4 gene. Other replicated associations with ADHD are outlined in the text. In autism, there is a replicated linkage finding on chromosome 7. Linkage studies in reading disability have confirmed a locus on chromosome 6 and strongly suggest one on chromosome 15.ConclusionsIn the next 5–10 years susceptibility genes for these disorders will be established. Describing their relationship to biological and behavioural function will be a far greater challenge.

scholarly journals Examination of Taxonomic Uncertainties Surrounding Brucella abortus bv. 7 by Phenotypic and Molecular Approaches

2013 ◽  
Vol 80 (5) ◽  
pp. 1570-1579 ◽  
Author(s):  
Bruno Garin-Bastuji ◽  
Virginie Mick ◽  
Gilles Le Carrou ◽  
Sebastien Allix ◽  
Lorraine L. Perrett ◽  
...  
Keyword(s):  
Brucella Abortus ◽  
Variable Number Tandem Repeat ◽  
Variable Number ◽  
Epidemiological Methods ◽  
Content Type ◽  
Phenotypic Profile ◽  
Molecular Approaches ◽  
Content Classification ◽  
Species Specific ◽  
Kenyan Strain

ABSTRACTBrucellataxonomy is perpetually being reshuffled, at both the species and intraspecies levels. Biovar 7 ofBrucella abortuswas suspended from theApproved Lists of Bacterial NamesBrucellaclassification in 1988, because of unpublished evidence that the reference strain 63/75 was a mixture ofB. abortusbiovars 3 and 5. To formally clarify the situation, all isolates previously identified asB. abortusbv. 7 in the AHVLA and ANSES strain collections were characterized by classical microbiological and multiple molecular approaches. Among the 14 investigated strains, including strain 63/75, only four strains, isolated in Kenya, Turkey, and Mongolia, were pure and showed a phenotypic profile in agreement with the former biovar 7, particularly agglutination with both anti-A/anti-M monospecific sera. These results were strengthened by molecular strategies. Indeed, genus- and species-specific methods allowed confirmation that the four pure strains belonged to theB. abortusspecies. The combination of most approaches excluded their affiliation with the recognized biovars (biovars 1 to 6 and 9), while some suggested that they were close to biovar 3.These assays were complemented by phylogenetic and/or epidemiological methods, such as multilocus sequence analysis (MLSA) and variable-number tandem repeat (VNTR) analysis. The results of this polyphasic investigation allow us to propose the reintroduction of biovar 7 into theBrucellaclassification, with at least three representative strains. Interestingly, the Kenyan strain, sharing the same biovar 7 phenotype, was genetically divergent from other three isolates. These discrepancies illustrate the complexity ofBrucellataxonomy. This study suggests that worldwide collections could include strains misidentified asB. abortusbv. 7, and it highlights the need to verify their real taxonomic position.

scholarly journals Isolation and Molecular Characterization ofBrucellaIsolates in Cattle Milk in Uganda

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Denis Rwabiita Mugizi ◽  
Shaman Muradrasoli ◽  
Sofia Boqvist ◽  
Joseph Erume ◽  
George William Nasinyama ◽  
...  
Keyword(s):  
Risk Factors ◽  
Genetic Variation ◽  
Brucella Abortus ◽  
Variable Number Tandem Repeat ◽  
Variable Number ◽  
Infected Cattle ◽  
Milk Samples ◽  
Molecular Approaches ◽  
Epidemiological Tool ◽  
The World

Brucellosis is endemic in livestock and humans in Uganda and its transmission involves a multitude of risk factors like consumption of milk from infected cattle. To shed new light on the epidemiology of brucellosis in Uganda the present study used phenotypic and molecular approaches to delineate theBrucellaspecies, biovars, and genotypes shed in cattle milk.Brucella abortuswithout a biovar designation was isolated from eleven out of 207 milk samples from cattle in Uganda. These isolates had a genomic monomorphism at 16 variable number tandem repeat (VNTR) loci and showed in turn high levels of genetic variation when compared with other African strains or otherB. abortusbiovars from other parts of the world. This study further highlights the usefulness of MLVA as an epidemiological tool for investigation ofBrucellainfections.

scholarly journals Clostridium difficile Isolates with High Linezolid MICs Harbor the Multiresistance Genecfr

2014 ◽  
Vol 59 (1) ◽  
pp. 586-589 ◽  
Author(s):  
Mercedes Marín ◽  
Adoración Martín ◽  
Luis Alcalá ◽  
Emilia Cercenado ◽  
Cristina Iglesias ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Molecular Mechanisms ◽  
Variable Number Tandem Repeat ◽  
Variable Number ◽  
23S Rrna ◽  
Rrna Gene ◽  
Ribosomal Protein Genes ◽  
Content Type ◽  
Linezolid Resistance ◽  
Methyltransferase Gene

ABSTRACTWe studied the molecular mechanisms of linezolid resistance in 9 isolates of toxigenicClostridium difficilewith high linezolid MICs. The activity of linezolid was determined against 891 clinical isolates of toxigenicC. difficile. The MIC50and MIC90of linezolid were 0.75 μg/ml and 1.5 μg/ml, respectively. Nine strains (1%) showed high linezolid MICs (6 μg/ml to 16 μg/ml) and also were resistant to clindamycin, erythromycin, and chloramphenicol. These strains were selected for molecular studies: sequencing of domain V of the23 rRNAgene, detection of thecfrmethyltransferase gene, and sequencing of the ribosomal protein genesrplCandrplD. Molecular relatedness between strains was assessed using PCR ribotyping and MLVA (multilocus variable-number tandem-repeat analysis) typing. The strains belonged to ribotypes 001 (2/9), 017 (6/9), and 078 (1/9). MLVA showed that strains of ribotype 001 and 017 belonged to the same clonal complex in each ribotype. We did not detect mutations in the 23S rRNA gene. Thecfrgene was detected in 7 of 9 strains. Sequencing ofcframplicons revealed a similarity of 100% to a fragment of transposon Tn6218ofC. difficile, which was annotated as a putative chloramphenicol/florfenicol resistance protein. We were unable to detect mechanisms of resistance to linezolid in the 2 strains belonging to ribotype 001. While the relevance of our results lies in the detection of thecfrgene as a possible mechanism of resistance to linezolid inC. difficile, our findings should be assessed by further investigations to characterize these possiblecfrgenes and their contribution to linezolid resistance.

scholarly journals The Prevalence of Virulence Determinants and Antibiotic Resistance Patterns in Methicillin—Resistant Staphylococcus aureus in a Nursing Home in Poland

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 427
Author(s):  
Martyna Kasela ◽  
Agnieszka Grzegorczyk ◽  
Bożena Nowakowicz-Dębek ◽  
Anna Malm
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Variable Number Tandem Repeat ◽  
Multidrug Resistant ◽  
Variable Number ◽  
Pulse Field ◽  
Virulence Determinants ◽  
Gene Encoding ◽  
Methicillin Resistant ◽  
Pulse Field Gel Electrophoresis

Nursing homes (NH) contribute to the regional spread of methicillin-resistant Staphylococcus aureus (MRSA). Moreover, residents are vulnerable to the colonization and subsequent infection of MRSA etiology. We aimed at investigating the molecular and phenotypic characteristics of 21 MRSA collected from the residents and personnel in an NH (Lublin, Poland) during 2018. All MRSA were screened for 20 genes encoding virulence determinants (sea-see, eta, etb, tst, lukS-F-PV, eno, cna, ebpS, fib, bbp, fnbA, fnbB, icaADBC) and for resistance to 18 antimicrobials. To establish the relatedness and clonal complexes of MRSA in NH we applied multiple-locus variable-number tandem-repeat fingerprinting (MLVF), pulse field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and staphylococcal cassette chromosome mec (SCCmec) typing. We identified four sequence types (ST) among two clonal complexes (CC): ST (CC22) known as EMRSA-15 as well as three novel STs—ST6295 (CC8), ST6293 (CC8) and ST6294. All tested MRSA were negative for sec, eta, etb, lukS-F-PV, bbp and ebpS genes. The most prevalent gene encoding toxin was sed (52.4%; n = 11/21), and adhesins were eno and fnbA (100%). Only 9.5% (n = 2/21) of MRSA were classified as multidrug-resistant. The emergence of novel MRSA with a unique virulence and the presence of epidemic clone EMRSA-15 creates challenges for controlling the spread of MRSA in NH.

scholarly journals Profiling variable-number tandem repeat variation across populations using repeat-pangenome graphs

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tsung-Yu Lu ◽  
Katherine M. Munson ◽  
Alexandra P. Lewis ◽  
Qihui Zhu ◽  
Luke J. Tallon ◽  
...  
Keyword(s):  
Tandem Repeats ◽  
Traditional Approach ◽  
Variable Number Tandem Repeat ◽  
Variable Number ◽  
Population Diversity ◽  
Protein Coding ◽  
Short Reads ◽  
Repeat Structure ◽  
Continental Population ◽  
Develop Software

AbstractVariable number tandem repeats (VNTRs) are composed of consecutive repetitive DNA with hypervariable repeat count and composition. They include protein coding sequences and associations with clinical disorders. It has been difficult to incorporate VNTR analysis in disease studies that use short-read sequencing because the traditional approach of mapping to the human reference is less effective for repetitive and divergent sequences. In this work, we solve VNTR mapping for short reads with a repeat-pangenome graph (RPGG), a data structure that encodes both the population diversity and repeat structure of VNTR loci from multiple haplotype-resolved assemblies. We develop software to build a RPGG, and use the RPGG to estimate VNTR composition with short reads. We use this to discover VNTRs with length stratified by continental population, and expression quantitative trait loci, indicating that RPGG analysis of VNTRs will be critical for future studies of diversity and disease.

scholarly journals Potentially Human-Pathogenic Escherichia coli O26 in Norwegian Sheep Flocks

2011 ◽  
Vol 77 (14) ◽  
pp. 4949-4958 ◽  
Author(s):  
C. Sekse ◽  
M. Sunde ◽  
B.-A. Lindstedt ◽  
P. Hopp ◽  
T. Bruheim ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Variable Number Tandem Repeat ◽  
Variable Number ◽  
Human Pathogens ◽  
Content Type ◽  
Representative Sampling ◽  
E Coli ◽  
Pathogenic Escherichia Coli ◽  
Close Relationship ◽  
Large Survey

ABSTRACTA national survey ofEscherichia coliO26 in Norwegian sheep flocks was conducted, using fecal samples to determine the prevalence. In total, 491 flocks were tested, andE. coliO26 was detected in 17.9% of the flocks. One hundred forty-twoE. coliO26 isolates were examined for flagellar antigens (H typing) and four virulence genes, includingstxandeae, to identify possible Shiga toxin-producingE. coli(STEC) and enteropathogenicE. coli(EPEC). Most isolates (129 out of 142) were identified asE. coliO26:H11. They possessedeaeand may have potential as human pathogens, although only a small fraction were identified as STEC O26:H11, giving a prevalence in sheep flocks of only 0.8%. Correspondingly, the sheep flock prevalence of atypical EPEC (aEPEC) O26:H11 was surprisingly high (15.9%). The genetic relationship between theE. coliO26:H11 isolates was investigated by pulsed-field gel electrophoresis (PFGE) and multilocus variable number tandem repeat analysis (MLVA), identifying 63 distinct PFGE profiles and 22 MLVA profiles. Although the MLVA protocol was less discriminatory than PFGE and a few cases of disagreement were observed, comparison by partition mapping showed an overall good accordance between the two methods. A close relationship between a few isolates of aEPEC O26:H11 and STEC O26:H11 was identified, but all theE. coliO26:H11 isolates should be considered potentially pathogenic to humans. The present study consisted of a representative sampling of sheep flocks from all parts of Norway. This is the first large survey of sheep flocks focusing onE. coliO26 in general, including results of STEC, aEPEC, and nonpathogenic isolates.

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