Página 1 dos resultados de 4394 itens digitais encontrados em 0.029 segundos

‣ Prevalence and nonrandom distribution of exonic mutations in interferon regulatory factor 6 in 307 families with Van der Woude syndrome and 37 families with popliteal pterygium syndrome

LIMA, Renata. L. L. Ferreira de; HOPER, Sarah A.; GHASSIBE, Michella; COOPER, Margaret E.; RORICK, Nicholas K.; KONDO, Shinji; KATZ, Lori; MARAZITA, Mary L.; COMPTON, John; BALE, Sherri; HEHR, Ute; DIXON, Michael J.; DAACK-HIRSCH, Sandra; BOUTE, Odile; BA
Fonte: LIPPINCOTT WILLIAMS & WILKINS Publicador: LIPPINCOTT WILLIAMS & WILKINS
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
58.02453%
Purpose: Interferon regulatory factor 6 encodes a member of the IRF family of transcription factors. Mutations in interferon regulatory factor 6 cause Van der Woude and popliteal pterygium syndrome, two related orofacial clefting disorders. Here, we compared and contrasted the frequency and distribution of exonic Mutations in interferon regulatory factor 6 between two large geographically distinct collections of families with Van der Woude and between one collection of families with popliteal pterygium syndrome. Methods: We performed direct sequence analysis of interferon regulatory factor 6 exons oil samples from three collections, two with Van der Woude and one with popliteal pterygium syndrome. Results: We identified mutations in interferon regulatory factor 6 exons in 68% of families in both Van der Woude collections and in 97% of families with popliteal pterygium syndrome. In sum, 106 novel disease-causing variants were found. The distribution of mutations in the interferon regulatory factor 6 exons in each collection was not random; exons 3, 4, 7, and 9 accounted for 80%. In the Van der Woude collections, the mutations were evenly divided between protein truncation and missense, whereas most mutations identified in the popliteal pterygium syndrome collection were missense. Further...

‣ Missense mutations but not allelic variants alter the function of ATM by dominant interference in patients with breast cancer

Scott, Shaun P.; Bendix, Regina; Chen, Philip; Clark, Raymond; Dörk, Thilo; Lavin, Martin F.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 22/01/2002 Português
Relevância na Pesquisa
48.14521%
The human genetic disorder ataxia-telangiectasia (A-T) is characterized by hypersensitivity to ionizing radiation and an elevated risk of malignancy. Epidemiological data support an increased risk for breast and other cancers in A-T heterozygotes. However, screening breast cancer cases for truncating mutations in the ATM (A-T mutated) gene has failed largely to reveal an increased incidence in these patients. It has been hypothesized that ATM missense mutations are implicated in breast cancer, and there is some evidence to support this. The presence of a large variety of rare missense variants in addition to common polymorphisms in ATM makes it difficult to establish such a relationship by association studies. To investigate the functional significance of these changes we have introduced missense substitutions, identified in either A-T or breast cancer patients, into ATM cDNA before establishing stable cell lines to determine their effect on ATM function. Pathogenic missense mutations and neutral missense variants were distinguished initially by their capacity to correct the radiosensitive phenotype in A-T cells. Furthermore missense mutations abolished the radiation-induced kinase activity of ATM in normal control cells, caused chromosome instability...

‣ Genetic and biochemical characterization of some missense mutations in the lacZ gene of Escherichia coli K-12.

Truman, P; Bergquist, P L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1976 Português
Relevância na Pesquisa
48.258066%
Some preparations of beta-galactosidase from strains of Escherichia coli carrying point mutations in their lacZ genes did not precipitate with antibody as effectively as wild-type enzyme, but did not appear to be chain-terminating mutations as judged by polarity measurements and suppression. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of crude extracts of induced Lac+ strains revealed that the monomer of beta-galactosidase ran as a band uncontaminated by other cellular proteins. This method was used to identify missense mutations in the alpha and beta portions of the lacZ gene. Six of 13 mutations investigated were judged to be missense by this criterion. Measurement of the degree of polarity, the ability to complement a nonsense mutation at the operator-distal extremity of the gene (omega-complementation), and suppressibility by 12 nonsense suppressors allowed the assignment of six other mutations as either number or ochre. The protein figments produced by these six nonsense mutations appeared to be degraded in vivo. One mutation that could not be classified was either a missense mutation whose protein product was degraded or a very leak nonsense mutation. Two lacZ alleles were suppressed by the ochre suppressors supM and supN...

‣ Missense Mutations in hMLH1 and hMSH2 Are Associated with Exonic Splicing Enhancers

Gorlov, Ivan P.; Gorlova, Olga Y.; Frazier, Marsha L.; Amos, Christopher I.
Fonte: The American Society of Human Genetics Publicador: The American Society of Human Genetics
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.3584%
There is a critical need to understand why missense mutations are deleterious. The deleterious effects of missense mutations are commonly attributed to their impact on primary amino acid sequence and protein structure. However, several recent studies have shown that some missense mutations are deleterious because they disturb cis-acting splicing elements—so-called “exonic splicing enhancers” (ESEs). It is not clear whether the ESE-related deleterious effects of missense mutations are common. We have evaluated colocalization of pathogenic missense mutations (found in affected individuals) with high-score ESE motifs in the human mismatch-repair genes hMSH2 and hMLH1. We found that pathogenic missense mutations in the hMSH2 and hMLH1 genes are located in ESE sites significantly more frequently than expected. Pathogenic missense mutations also tended to decrease ESE scores, thus leading to a higher propensity for splicing defects. In contrast, nonpathogenic missense mutations (polymorphisms found in unaffected individuals) and nonsense mutations are distributed randomly in relation to ESE sites. Comparison of the observed and expected frequencies of missense mutations in ESE sites shows that pathogenic effects of ⩾20% of mutations in hMSH2 result from disruption of ESE sites and disturbed splicing. Similarly...

‣ Missense mutations and evolutionary conservation of amino acids: evidence that many of the amino acids in factor IX function as "spacer" elements.

Bottema, C D; Ketterling, R P; Ii, S; Yoon, H S; Phillips, J A; Sommer, S S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1991 Português
Relevância na Pesquisa
48.225244%
We report 31 point mutations in the factor IX gene and explore the relationship between the level of evolutionary conservation of an amino acid and the probability of a mutation causing hemophilia B. From our total sample of 125 hemophiliacs and from those reported by others, we identify 95 independent missense mutations, 94 of which occur at amino acids that are evolutionarily conserved in the available mammalian factor IX sequences. The likelihood of a missense mutation causing hemophilia B depends on whether the residue is also conserved in the factor IX-related proteases: factor VII, factor X, and protein C. Most of the possible missense mutations in generically conserved residues (i.e., those conserved in factor IX and in all the related proteases) should cause disease. In contrast, missense mutations in factor IX-specific residues (i.e., those conserved in human, cow, dog, and mouse factor IX but not in the related proteases) are sixfold less likely to cause disease. Missense mutations at nonconserved residues are 33-fold less likely to cause disease. At least three models are compatible with these observations. A comparison of sequence alignments from four and nine species of factor IX and an examination of the missense mutations occurring at CpG residues suggest a model in which most residues fall on opposite ends of a spectrum. In about 40% of residues...

‣ Missense Mutations in Fumarate Hydratase in Multiple Cutaneous and Uterine Leiomyomatosis and Renal Cell Cancer

Alam, N. Afrina; Olpin, Simon; Rowan, Andrew; Kelsell, David; Leigh, Irene M.; Tomlinson, Ian P. M.; Weaver, Todd
Fonte: American Society for Investigative Pathology Publicador: American Society for Investigative Pathology
Tipo: Artigo de Revista Científica
Publicado em /10/2005 Português
Relevância na Pesquisa
48.241455%
Heterozygous germline mutations in fumarate hydratase (FH) predispose to the multiple cutaneous and uterine leiomyomatosis syndrome (MCUL), which, when co-existing with renal cancer, is also known as hereditary leiomyomatosis and renal cell cancer. Twenty-seven distinct missense mutations represent 68% of FH mutations reported in MCUL. Here we show that FH missense mutations significantly occurred in fully conserved residues and in residues functioning in the FH A-site, B-site, or subunit-interacting region. Of 24 distinct missense mutations, 13 (54%) occurred in the substrate-binding A-site, 4 (17%) in the substrate-binding B-site, and 7 (29%) in the subunit-interacting region. Clustering of missense mutations suggested the presence of possible mutational hotspots. FH functional assay of lymphoblastoid cell lines from 23 individuals with heterozygous FH missense mutations showed that A-site mutants had significantly less residual activity than B-site mutants, supporting data from Escherichia coli that the A-site is the main catalytic site. Missense FH mutations predisposing to renal cancer had no unusual features, and identical mutations were found in families without renal cancer, suggesting a role for genetic or environmental factors in renal cancer development in MCUL. That all missense FH mutations associating with MCUL/hereditary leiomyomatosis and renal cell cancer showed diminished FH enzymatic activity suggests that the tumor suppressor role of fumarate hydratase may relate to its enzymatic function.

‣ TBX22 Missense Mutations Found in Patients with X-Linked Cleft Palate Affect DNA Binding, Sumoylation, and Transcriptional Repression

Andreou, Artemisia M. ; Pauws, Erwin ; Jones, Marius C. ; Singh, Manvendra K. ; Bussen, Markus ; Doudney, Kit ; Moore, Gudrun E. ; Kispert, Andreas ; Brosens, Jan J. ; Stanier, Philip 
Fonte: American Society of Human Genetics Publicador: American Society of Human Genetics
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.137793%
The T-box transcription factor TBX22 is essential for normal craniofacial development, as demonstrated by the finding of nonsense, frameshift, splice-site, or missense mutations in patients with X-linked cleft palate (CPX) and ankyloglossia. To better understand the function of TBX22, we studied 10 different naturally occurring missense mutations that are phenotypically equivalent to loss-of-function alleles. Since all missense mutations are located in the DNA-binding T-box domain, we first investigated the preferred recognition sequence for TBX22. Typical of T-box proteins, the resulting sequence is a palindrome based around near-perfect copies of AGGTGTGA. DNA-binding assays indicate that missense mutations at or near predicted contact points with the DNA backbone compromise stable DNA-protein interactions. We show that TBX22 functions as a transcriptional repressor and that TBX22 missense mutations result in impaired repression activity. No effect on nuclear localization of TBX22 was observed. We find that TBX22 is a target for the small ubiquitin-like modifier SUMO-1 and that this modification is required for TBX22 repressor activity. Although the site of SUMO attachment at the lysine at position 63 is upstream of the T-box domain...

‣ Bladder tumour-derived somatic TSC1 missense mutations cause loss of function via distinct mechanisms

Pymar, Louis S.; Platt, Fiona M.; Askham, Jon M.; Morrison, Ewan E.; Knowles, Margaret A.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.2054%
More than 50% of transitional cell carcinomas of the bladder show loss of heterozygosity of a region spanning the TSC1 locus at 9q34 and mutations of TSC1 have been identified in 14.5% of tumours. These comprise nonsense mutations, splicing mutations, small deletions and missense mutations. Missense mutations are only rarely found in the germline in TSC disease. Therefore, we have examined six somatic missense mutations found in bladder cancer to determine whether these result in loss of function. We describe loss of function via distinct mechanisms. Five mutations caused mutually exclusive defects at mRNA and protein levels. Of these, two mutations caused pre-mRNA splicing errors that were predicted to result in premature protein truncation and three resulted in markedly reduced stability of exogenous TSC1 protein. Primary tumours with aberrant TSC1 pre-mRNA splicing were confirmed as negative for TSC1 expression by immunohistochemistry. Expression was also significantly reduced in a tumour with a TSC1 missense mutation resulting in diminished protein half-life. A single TSC1 missense mutation identified in a tumour with retained heterozygosity of the TSC1 region on chromosome 9 caused an apparently TSC2- and mTOR-independent localization defect of the mutant protein. We conclude that although TSC1 missense mutations do not play a major role in causation of TSC disease...

‣ Cancer-specific High-throughput Annotation of Somatic Mutations: computational prediction of driver missense mutations

Carter, Hannah; Chen, Sining; Isik, Leyla; Tyekucheva, Svitlana; Velculescu, Victor E.; Kinzler, Kenneth W.; Vogelstein, Bert; Karchin, Rachel
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.15933%
Large-scale sequencing of cancer genomes has uncovered thousands of DNA alterations, but the functional relevance of the majority of these mutations to tumorigenesis is unknown. We have developed a computational method, called CHASM (Cancer-specific High-throughput Annotation of Somatic Mutations), to identify and prioritize those missense mutations most likely to generate functional changes that enhance tumor cell proliferation. The method has high sensitivity and specificity when discriminating between known driver missense mutations and randomly generated missense mutations (area under ROC curve > 0.91, area under Precision-Recall curve > 0.79). CHASM substantially outperformed previously described missense mutation function prediction methods at discriminating known oncogenic mutations in TP53 and the tyrosine kinase EGFR. We applied the method to 607 missense mutations found in a recent glioblastoma multiforme sequencing (GBM) study. Based on a model that assumed the GBM mutations are a mixture of drivers and passengers, we estimate that 8% of these mutations are drivers, causally contributing to tumorigenesis.

‣ SYSTEMATIC BIOCHEMICAL ANALYSIS OF SOMATIC MISSENSE MUTATIONS IN DNA POLYMERASE β FOUND IN PROSTATE CANCER REVEAL ALTERATION OF ENZYMATIC FUNCTION

An, ChangLong; Chen, Desheng; Makridakis, Nick M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.091724%
DNA polymerase β is essential for short-patch base excision repair. We have previously identified 20 somatic pol β mutations in prostate tumors, many of them missense. In the current paper we describe the effect of all of these somatic missense pol β mutations (p.K27N, p.E123K, p.E232K, p.P242R, p.E216K, p.M236L, and the triple mutant p.P261L/ T292A/ I298T) on the biochemical properties of the polymerase in vitro, following bacterial expression and purification of the respective enzymatic variants. We report that all missense somatic pol β mutations significantly affect enzyme function. Two of the pol β variants reduce catalytic efficiency, while the remaining five missense mutations alter the fidelity of DNA synthesis. Thus we conclude that a significant proportion (9 out of 26; 35%) of prostate cancer patients have functionally important somatic mutations of pol β. Many of these missense mutations are clonal in the tumors, and/or are associated with loss of heterozygosity and microsatellite instability. These results suggest that interfering with normal polymerase β function may be a frequent mechanism of prostate tumor progression. Furthermore, the availability of detailed structural information for pol β allows understanding of the potential mechanistic effects of these mutants on polymerase function.

‣ Common Pathogenic Effects of Missense Mutations in the P-Type ATPase ATP13A2 (PARK9) Associated with Early-Onset Parkinsonism

Podhajska, Agata; Musso, Alessandra; Trancikova, Alzbeta; Stafa, Klodjan; Moser, Roger; Sonnay, Sarah; Glauser, Liliane; Moore, Darren J.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 29/06/2012 Português
Relevância na Pesquisa
48.280938%
Mutations in the ATP13A2 gene (PARK9) cause autosomal recessive, juvenile-onset Kufor-Rakeb syndrome (KRS), a neurodegenerative disease characterized by parkinsonism. KRS mutations produce truncated forms of ATP13A2 with impaired protein stability resulting in a loss-of-function. Recently, homozygous and heterozygous missense mutations in ATP13A2 have been identified in subjects with early-onset parkinsonism. The mechanism(s) by which missense mutations potentially cause parkinsonism are not understood at present. Here, we demonstrate that homozygous F182L, G504R and G877R missense mutations commonly impair the protein stability of ATP13A2 leading to its enhanced degradation by the proteasome. ATP13A2 normally localizes to endosomal and lysosomal membranes in neurons and the F182L and G504R mutations disrupt this vesicular localization and promote the mislocalization of ATP13A2 to the endoplasmic reticulum. Heterozygous T12M, G533R and A746T mutations do not obviously alter protein stability or subcellular localization but instead impair the ATPase activity of microsomal ATP13A2 whereas homozygous missense mutations disrupt the microsomal localization of ATP13A2. The overexpression of ATP13A2 missense mutants in SH-SY5Y neural cells does not compromise cellular viability suggesting that these mutant proteins lack intrinsic toxicity. However...

‣ Disease-Causing Missense Mutations in Human DNA Helicase Disorders

Suhasini, Avvaru N.; Brosh, Robert M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.2054%
Helicases have important roles in nucleic acid metabolism, and their prominence is marked by the discovery of genetic disorders arising from disease-causing mutations. Missense mutations can yield unique insight to molecular functions and basis for disease pathology. XPB or XPD missense mutations lead to Xeroderma pigmentosum, Cockayne’s syndrome, Trichothiodystrophy, or COFS syndrome, suggesting that DNA repair and transcription defects are responsible for clinical heterogeneity. Complex phenotypes are also observed for RECQL4 helicase mutations responsible for Rothmund-Thomson syndrome, Baller-Gerold syndrome, or RAPADILINO. Bloom’s syndrome causing missense mutations are found in the conserved helicase and RecQ C-terminal domain of BLM that interfere with helicase function. Although rare, patient-derived missense mutations in the exonuclease or helicase domain of Werner syndrome protein exist. Characterization of WRN separation-of-function mutants may provide insight to catalytic requirements for suppression of phenotypes associated with the premature aging disorder. Characterized FANCJ missense mutations associated with breast cancer or Fanconi anemia interfere with FANCJ helicase activity required for DNA repair and the replication stress response. For example...

‣ Missense Mutations in FBN1 Exons 41 and 42 Cause Weill-Marchesani Syndrome with Thoracic Aortic Disease and Marfan Syndrome

Cecchi, Alana; Ogawa, Naomi; Martinez, Hugo R.; Carlson, Alicia; Fan, Yuxin; Penny, Daniel J.; Guo, Dong-chuan; Eisenberg, Steven; Safi, Hazim; Estrera, Anthony; Lewis, Richard A.; Meyers, Deborah; Milewicz, Dianna M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.19626%
Mutations in FBN1 cause a range of overlapping but distinct conditions including Marfan syndrome (MFS), Weill-Marchesani syndrome (WMS), familial thoracic aortic aneurysms/dissections (FTAAD), acromicric dysplasia (AD), and geleophysic dysplasia (GD). Two forms of acromelic dysplasia, AD and GD, characterized by short stature, brachydactyly, reduced joint mobility, and characteristic facies, result from heterozygous missense mutations occurring in exons 41 and 42 of FBN1; missense mutations in these exons have not been reported to cause MFS or other syndromes. Here we report on probands with MFS and WMS who have heterozygous FBN1 missense mutations in exons 41 and 42, respectively. The proband with WMS has ectopia lentis, short stature, thickened pinnae, tight skin, striae atrophicae, reduced extension of the elbows, contractures of the fingers and toes, and brachydactyly and has a missense mutation in exon 42 of FBN1 (c.5242T>C ;p.C1748R). He also experienced a previously unreported complication of WMS, an acute thoracic aortic dissection. The second proband displays classic characteristics of MFS, including ectopia lentis, skeletal features and aortic root dilatation, and has a missense mutation in exon 41 of FBN1 (c.5084G>A; p.C1695Y). These phenotypes provide evidence that missense mutations in exons 41 and 42 of FBN1 lead to MFS and WMS in addition to AD and GD and also suggest that all individuals with pathogenic FBN1 mutations in these exons should be assessed for thoracic aortic disease and ectopia lentis. Further studies are necessary to elucidate the factors responsible for the different phenotypes associated with missense mutations in these exons of FBN1.

‣ Protein Stability and in Vivo Concentration of Missense Mutations in Phenylalanine Hydroxylase

Shi, Zhen; Sellers, Jenn; Moult, John
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.114136%
A previous computational analysis of missense mutations linked to monogenic disease found a high proportion of missense mutations affect protein stability, rather than other aspects of protein structure and function. The purpose of the present study is to relate the presence of such stability damaging missense mutations to the levels of a particular protein present under ‘in vivo’ like conditions, and to test the reliability of the computational methods. Experimental data on a set of missense mutations of the enzyme phenylalanine hydroxylase (PAH) associated with the monogenic disease phenylketonuria (PKU) have been compared with the expected in vivo impact on protein function, obtained using SNPs3D, an in silico analysis package. A high proportion of the PAH mutations are predicted to be destabilizing. The overall agreement between predicted stability impact and experimental evidence for lower protein levels is in accordance with the estimated error rates of the methods. For these mutations, destabilization of protein three dimensional structure is the major molecular mechanism leading to PKU, and results in a substantial reduction of in vivo PAH protein concentration. Although of limited scale, the results support the view that destabilization is the most common mechanism by which missense mutations cause monogenic disease. In turn...

‣ An integrated computational approach can classify VHL missense mutations according to risk of clear cell renal carcinoma

Gossage, Lucy; Pires, Douglas E. V.; Olivera-Nappa, Álvaro; Asenjo, Juan; Bycroft, Mark; Blundell, Tom L.; Eisen, Tim
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.091724%
Mutations in the von Hippel–Lindau (VHL) gene are pathogenic in VHL disease, congenital polycythaemia and clear cell renal carcinoma (ccRCC). pVHL forms a ternary complex with elongin C and elongin B, critical for pVHL stability and function, which interacts with Cullin-2 and RING-box protein 1 to target hypoxia-inducible factor for polyubiquitination and proteasomal degradation. We describe a comprehensive database of missense VHL mutations linked to experimental and clinical data. We use predictions from in silico tools to link the functional effects of missense VHL mutations to phenotype. The risk of ccRCC in VHL disease is linked to the degree of destabilization resulting from missense mutations. An optimized binary classification system (symphony), which integrates predictions from five in silico methods, can predict the risk of ccRCC associated with VHL missense mutations with high sensitivity and specificity. We use symphony to generate predictions for risk of ccRCC for all possible VHL missense mutations and present these predictions, in association with clinical and experimental data, in a publically available, searchable web server.

‣ In silico prediction of tumor antigens derived from functional missense mutations of the cancer gene census

Khalili, Jahan S.; Hanson, Russell W.; Szallasi, Zoltan
Fonte: Landes Bioscience Publicador: Landes Bioscience
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
57.879907%
Antigen-specific immune responses against peptides derived from missense gene mutations have been identified in multiple cancers. The application of personalized peptide vaccines based on the tumor mutation repertoire of each cancer patient is a near-term clinical reality. These peptides can be identified for pre-validation by leveraging the results of massive gene sequencing efforts in cancer. In this study, we utilized NetMHC 3.2 to predict nanomolar peptide binding affinity to 57 human HLA-A and B alleles. All peptides were derived from 5,685 missense mutations in 312 genes annotated as functionally relevant in the Cancer Genome Project. Of the 26,672,189 potential 8–11 mer peptide-HLA pairs evaluated, 0.4% (127,800) display binding affinities < 50 nM, predicting high affinity interactions. These peptides can be segregated into two groups based on the binding affinity to HLA proteins relative to germline-encoded sequences: peptides for which both the mutant and wild-type forms are high affinity binders, and peptides for which only the mutant form is a high affinity binder. Current evidence directs the attention to mutations that increase HLA binding affinity, as compared with cognate wild-type peptide sequences, as these potentially are more relevant for vaccine development from a clinical perspective. Our analysis generated a database including all predicted HLA binding peptides and the corresponding change in binding affinity as a result of point mutations. Our study constitutes a broad foundation for the development of personalized peptide vaccines that hone-in on functionally relevant targets in multiple cancers in individuals with diverse HLA haplotypes.

‣ ARX homeodomain mutations abolish DNA binding and lead to a loss of transcriptional repression

Shoubridge, C.; Tan, M.; Seiboth, G.; Gecz, J.
Fonte: Oxford Univ Press Publicador: Oxford Univ Press
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
Relevância na Pesquisa
48.11792%
Mutations in the Aristaless-related homeobox (ARX) gene are one of the most frequent causes of X-linked intellectual disability (ID). Several missense mutations, clustered in the paired-type homeodomain of ARX, have been identified. These mutations lead to a range of phenotypes from X-linked lissencephaly with abnormal genitalia to seizure disorders without brain malformations including X-linked infantile spasms with ID (ISSX-ID) and X-linked myoclonic epilepsy with spasticity and ID (XMESID). The effect of these mutations on the DNA-binding and transcriptional activity has been evaluated. Luciferase reporter assays showed altered repression activity of ARX by all mutations, causing brain malformations and ISSX-ID phenotypes, but not by the P353L mutation implicated in a milder phenotype of XMESID. Similarly, transient overexpression of wild-type ARX repressed endogenous expression of known ARX targets, LMO1 and SHOX2, when measured by real-time quantitative polymerase chain reaction. Overall, the molecular consequence of missense mutations correlated well with the severity of the clinical phenotype. In all mutations tested, except P353L, the DNA binding was abolished. Electrophoretic mobility shift assay results were validated using chromatin immunoprecipitation following overexpression of normal and selected missense mutations. Unlike wild-type ARX and clinically less severe mutations...

‣ Mutationsanalyse des HFE-Genes mittels DHPLC bei Hämochromatose-Patienten und Parkinson-Patienten; Screening for mutations of the HFE-gene by the method of DHPLC in hemochromatosis patients and Parkinson’s disease patients

Akbas, Nilgün
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
48.19355%
Bei der HFE-assoziierten Hereditären Hämochromatose (HH1) handelt es sich um ein monogen vererbtes Krankheitssyndrom, bei welchem es aufgrund von Sequenzvariationen im HFE-Gen zu einer exzessiven Eisenspeicherung mit folgender Schädigung diverser Organsysteme kommt. Die wichtigsten, mit dieser Erkrankung assoziierten Genotypen sind dabei die homozygote C282Y-Mutation in Exon 4, die homozygote H63D-Mutation in Exon 2 und die Compound-Heterozygotie für diese zwei Mutationen. Diese Genotypen können bei vielen Individuen, aber bei weitem nicht allen Individuen mit entsprechendem Phänotyp nachgewiesen werden. Auch bei der routinemäßig durchgeführten molekulargenetischen Analyse des hier untersuchten HH1-Kollektives konnte nur für einen Teil der insgesamt 116 Patienten ein entsprechender Genotyp festgestellt werden. Daher wurden im Rahmen dieser Arbeit alle 6 Exons des HFE-Genes innerhalb dieses Kollektives mittels DHPLC und Sequenzierung untersucht. Hierbei konnte das Vorliegen der zwei Hauptmutationen der HH1 als exonische missense-Mutationen und eine intronische Sequenzvariation (IVS2/3889*T>C) nachgewiesen werden, über deren Bedeutung noch keinerlei Klarheit besteht. Mit Hilfe einer Stammbaumanalyse konnte außerdem eine Kopplung der H63D-Mutation mit dieser intronischen Sequenzvariation festgestellt werden. Neben der genetischen Untersuchung wurde retrospektiv für jeden Patienten die vorliegende Klinik anhand eines Patientenbogens erhoben. So konnten Vergleiche zwischen dem vorliegenden Genotyp und Phänotyp durchgeführt werden. Hierzu wurden die Patienten...

‣ New mutations in the GLA gene in Brazilian families with Fabry disease

Turaca, Lauro Thiago; Pessoa, Juliana Gilbert; Motta, Fabiana Louise; Munoz Rojas, Maria Veronica; Mueller, Karen Barbosa; Lourenço, Charles Marques; Marques Júnior, Wilson; D'Almeida, Vania; Martins, Ana Maria; Pesquero, Joao Bosco
Fonte: NATURE PUBLISHING GROUP; NEW YORK Publicador: NATURE PUBLISHING GROUP; NEW YORK
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
57.590864%
Fabry disease (FD) is an X-linked inborn error of glycosphingolipid catabolism that results from mutations in the alpha-galactosidase A (GLA) gene. Evaluating the enzymatic activity in male individuals usually performs the diagnosis of the disease, but in female carriers the diagnosis based only on enzyme assays is often inconclusive. In this work, we analyzed 568 individuals from 102 families with suspect of FD. Overall, 51 families presented 38 alterations in the GLA gene, among which 19 were not previously reported in literature. The alterations included 17 missense mutations, 7 nonsense mutations, 7 deletions, 6 insertions and 1 in the splice site. Six alterations (R112C, R118C, R220X, R227X, R342Q and R356W) occurred at CpG dinucleotides. Five mutations not previously described in the literature (A156D, K237X, A292V, I317S, c.1177_1178insG) were correlated with low GLA enzyme activity and with prediction of molecular damages. From the 13 deletions and insertions, 7 occurred in exons 6 or 7 (54%) and 11 led to the formation of a stop codon. The present study highlights the detection of new genomic alterations in the GLA gene in the Brazilian population, facilitating the selection of patients for recombinant enzyme-replacement trials and offering the possibility to perform prenatal diagnosis. Journal of Human Genetics (2012) 57...

‣ Identification and characterization of two missense mutations causing factor XIIIA deficiency

Kangsadalampai, S; Chelvanayagam, Gareth; Baker, Rohan; Kuperan, Ponnudarai; Board, Philip
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
57.55299%
In this study, two amino acid substitutions. Arg260His and Val414Phe, have been identified in the factor XIIIA subunits of factor XIII deficient patients of Syrian and Indian descent, respectively. To confirm the deleterious effects of these substitutions, both variant sequences have been engineered into cDNA clones and the mutant enzymes expressed in yeast. Determination of the transglutaminase activity and immuno detection of the mutant enzymes together with mRNA hybridization revealed that the mutations dramatically reduce both the catalytic activity and the level of enzyme expressed in yeast. The mutations Arg260His and Val414Phe occur within the 'core' domain of the enzyme. Computer modelling of the mutant enzymes reveals that the substitution of the Arg260 by His results in the loss of a conserved electrostatic interaction whereas the effect of the Val414Phe substitution is a consequence of the large increase in side-chain volume. Although both mutations do not effect the active site directly, they are predicted to reduce the stability of the enzyme. The effects of these two amino acid substitutions on enzyme expression and three-dimensional structure strongly confirm that residues which are located outside of the active site can have a significant effect on protein stability and function.