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‣ Structure of tau exon 10 splicing regulatory element RNA and destabilization by mutations of frontotemporal dementia and parkinsonism linked to chromosome 17

Varani, Luca; Hasegawa, Masato; Spillantini, Maria Grazia; Smith, Michael J.; Murrell, Jill R.; Ghetti, Bernardino; Klug, Aaron; Goedert, Michel; Varani, Gabriele
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 06/07/1999 Português
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Coding region and intronic mutations in the tau gene cause frontotemporal dementia and parkinsonism linked to chromosome 17. Intronic mutations and some missense mutations increase splicing in of exon 10, leading to an increased ratio of four-repeat to three-repeat tau isoforms. Secondary structure predictions have led to the proposal that intronic mutations and one missense mutation destabilize a putative RNA stem-loop structure located close to the splice-donor site of the intron after exon 10. We have determined the three-dimensional structure of this tau exon 10 splicing regulatory element RNA by NMR spectroscopy. We show that it forms a stable, folded stem-loop structure whose thermodynamic stability is reduced by frontotemporal dementia and parkinsonism linked to chromosome 17 mutations and increased by compensatory mutations. By exon trapping, the reduction in thermodynamic stability is correlated with increased splicing in of exon 10.

‣ Functional analyses of troponin T mutations that cause hypertrophic cardiomyopathy: Insights into disease pathogenesis and troponin function

Sweeney, H. Lee; Feng, Huisheng S.; Yang, Zhaouhui; Watkins, Hugh
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 24/11/1998 Português
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Mutations in a number of cardiac sarcomeric protein genes cause hypertrophic cardiomyopathy (HCM). Previous findings indicate that HCM-causing mutations associated with a truncated cardiac troponin T (TnT) and missense mutations in the β-myosin heavy chain share abnormalities in common, acting as dominant negative alleles that impair contractile performance. In contrast, Lin et al. [Lin, D., Bobkova, A., Homsher, E. & Tobacman, L. S. (1996) J. Clin. Invest. 97, 2842–2848] characterized a TnT point mutation (Ile79Asn) and concluded that it might lead to hypercontractility and, thus, potentially a different mechanism for HCM pathogenesis. In this study, three HCM-causing cardiac TnT mutations (Ile79Asn, Arg92Gln, and ΔGlu160) were studied in a myotube expression system. Functional studies of wild-type and mutant transfected myotubes revealed that all three mutants decreased the calcium sensitivity of force production and that the two missense mutations (Ile79Asn and Arg92Gln) increased the unloaded shortening velocity nearly 2-fold. The data demonstrate that TnT can alter the rate of myosin cross-bridge detachment, and thus the troponin complex plays a greater role in modulating muscle contractile performance than was recognized previously. Furthermore...

‣ Mutations in the CYP11B1 gene causing congenital adrenal hyperplasia and hypertension cluster in exons 6, 7, and 8.

Curnow, K M; Slutsker, L; Vitek, J; Cole, T; Speiser, P W; New, M I; White, P C; Pascoe, L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/05/1993 Português
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Steroid 11 beta-hydroxylase deficiency (failure to convert 11-deoxycortisol to cortisol) is the second most common cause of congenital adrenal hyperplasia and results in a hypertensive form of the disease. The 11 beta-hydroxylase enzyme is encoded by the CYP11B1 gene on chromosome 8q22. Two mutations in CYP11B1 have previously been reported in patients with 11 beta-hydroxylase deficiency--Arg-448-->His and a 2-bp insertion in codon 394. We now report eight previously uncharacterized mutations causing this disorder. Seven are point mutations (three nonsense and four missense) and one is a single base pair deletion causing a frameshift. We have used an in vitro transfection assay to show that all five known missense mutations causing 11 beta-hydroxylase deficiency abolish enzymatic activity. In principle, deletions of CYP11B1 could be generated by unequal crossing-over between CYP11B1 and the adjacent CYP11B2 gene, but no such deletions were found among the deficiency alleles in this study. Seven of the 10 known mutations are clustered in exons 6-8, a nonrandom distribution within the gene. This may reflect the location of functionally important amino acid residues within the enzyme or an increased tendency to develop mutations within this region of the gene.

‣ Functional consequences of Rett syndrome mutations on human MeCP2

Yusufzai, Timur M.; Wolffe, Alan P.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Publicado em 01/11/2000 Português
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The neurodevelopmental disorder known as Rett syndrome has recently been linked to the methyl-CpG-binding transcriptional repressor, MeCP2. In this report we examine the consequences of these mutations on the function of MeCP2. The ability to bind specifically to methylated DNA and the transcription repression capabilities are tested, as well as the stability of proteins in vivo. We find that all missense mutations (R106W, R133C, F155S, T158M) within the methyl-binding domain impair selectivity for methylated DNA, and that all nonsense mutations (L138X, R168X, E235X, R255X, R270X, V288X, R294X) that truncate all or some of the transcriptional repression domain (TRD) affect the ability to repress transcription and have decreased levels of stability in vivo. Two missense mutations, one in the TRD (R306C) and one in the C-terminus (E397K), had no noticeable effects on MeCP2 function. Together, these results provide evidence of how Rett syndrome mutations can affect distinct functions of MeCP2 and give insight into these mutations that may contribute to the disease.

‣ Clinical and prognostic evaluation of familial hypertrophic cardiomyopathy in two South African families with different cardiac beta myosin heavy chain gene mutations.

Posen, B. M.; Moolman, J. C.; Corfield, V. A.; Brink, P. A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1995 Português
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BACKGROUND--Familial hypertrophic cardiomyopathy is the most common inherited cardiac disorder, with sudden cardiac death at a young age the most frequent cause of death in affected individuals. Some cases of familial hypertrophic cardiomyopathy are caused by missense mutations of the beta myosin heavy chain (beta MHC) gene on chromosome 14 and at least 17 such mutations have been described. Recent reports suggest that a correlation exists between a specific beta MHC gene mutation and prognosis in familial hypertrophic cardiomyopathy. This premise is currently being used as a basis to provide counselling for affected families. This mutation/prognosis association, however, has not been widely assessed as yet. The clinical and prognostic features of two South African families of mixed racial descent, in which different beta MHC gene mutations were segregating, were studied to evaluate this correlation. The results were compared with those of previously published reports of European families carrying the same mutations. METHODS--The beta MHC gene missense mutations in two affected families were identified by single strand conformation polymorphism analysis and sequencing (pedigree 106: Arg403Trp; pedigree 108: Arg249Gln). All family members were subjected to genotypic analysis using polymerase chain reaction amplification and restriction enzyme based mutation detection techniques. Clinical...

‣ Rett Syndrome and Beyond: Recurrent Spontaneous and Familial MECP2 Mutations at CpG Hotspots

Wan, Mimi; Lee, Stephen Sung Jae; Zhang, Xianyu; Houwink-Manville, Isa; Song, Hae-Ri; Amir, Ruthie E.; Budden, Sarojini; Naidu, SakkuBai; Pereira, Jose Luiz P.; Lo, Ivan F. M.; Zoghbi, Huda Y.; Schanen, N. Carolyn; Francke, Uta
Fonte: The American Society of Human Genetics Publicador: The American Society of Human Genetics
Tipo: Artigo de Revista Científica
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Rett syndrome (RTT) is a neurodevelopmental disorder characterized by loss of acquired skills after a period of normal development in infant girls. The responsible gene, encoding methyl-CpG binding protein 2 (MeCP2), was recently discovered. Here we explore the spectrum of phenotypes resulting from MECP2 mutations. Both nonsense (R168X and R255X) and missense (R106W and R306C) mutations have been found, with multiple recurrences. R168X mutations were identified in six unrelated sporadic cases, as well as in two affected sisters and their normal mother. The missense mutations were de novo and affect conserved domains of MeCP2. All of the nucleotide substitutions involve C→T transitions at CpG hotspots. A single nucleotide deletion, at codon 137, that creates a L138X stop codon within the methyl-binding domain was found in an individual with features of RTT and incontinentia pigmenti. An 806delG deletion causing a V288X stop in the transcription-repression domain was identified in a woman with motor-coordination problems, mild learning disability, and skewed X inactivation; in her sister and daughter, who were affected with classic RTT; and in her hemizygous son, who died from congenital encephalopathy. Thus, some males with RTT-causing MECP2 mutations may survive to birth...

‣ Identification of 31 novel mutations in the F8 gene in Spanish hemophilia A patients: structural analysis of 20 missense mutations suggests new intermolecular binding sites

Venceslá, Adoración; Corral-Rodríguez, María Ángeles; Baena, Manel; Cornet, Mónica; Domènech, Montserrat; Baiget, Montserrat; Fuentes-Prior, Pablo; Tizzano, Eduardo F.
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 01/04/2008 Português
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Hemophilia A (HA) is an X-linked bleeding disorder caused by a wide variety of mutations in the factor 8 (F8) gene, leading to absent or deficient factor VIII (FVIII). We analyzed the F8 gene of 267 unrelated Spanish patients with HA. After excluding patients with the common intron-1 and intron-22 inversions and large deletions, we detected 137 individuals with small mutations, 31 of which had not been reported previously. Eleven of these were nonsense, frameshift, and splicing mutations, whereas 20 were missense changes. We assessed the impact of the 20 substitutions based on currently available information about FV and FVIII structure and function relationship, including previously reported results of replacements at these and topologically equivalent positions. Although most changes are likely to cause gross structural perturbations and concomitant cofactor instability, p.Ala375Ser is predicted to affect cofactor activation. Finally, 3 further mutations (p.Pro64Arg, p.Gly494Val, and p.Asp2267Gly) appear to affect cofactor interactions with its carrier protein, von Willebrand factor, with the scavenger receptor low-density lipoprotein receptor–related protein (LRP), and/or with the substrate of the FVIIIapi•FIXa (Xase) complex...

‣ Five novel mutations in steroidogenic factor 1 (SF1, NR5A1) in 46,XY patients with severe underandrogenization but without adrenal insufficiency

Köhler, Birgit; Lin, Lin; Ferraz-de-Souza, Bruno; Wieacker, Peter; Heidemann, Peter; Schröder, Vanessa; Biebermann, Heike; Schnabel, Dirk; Grüters, Annette; Achermann, John C
Fonte: Wiley Subscription Services, Inc., A Wiley Company Publicador: Wiley Subscription Services, Inc., A Wiley Company
Tipo: Artigo de Revista Científica
Publicado em /01/2008 Português
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Steroidogenic factor 1 (SF1, NR5A1) is a nuclear receptor that regulates multiple genes involved in adrenal and gonadal development, steroidogenesis, and the reproductive axis. Human mutations in SF1 were initially found in two 46,XY female patients with severe gonadal dysgenesis and primary adrenal failure. However, more recent case reports have suggested that heterozygous mutations in SF1 may also be found in patients with 46,XY partial gonadal dysgenesis and underandrogenization but normal adrenal function. We have analyzed the gene encoding SF1 (NR5A1) in a cohort of 27 patients with 46,XY disorders of sex development (DSD) from the German network of DSD. Heterozygous SF1 mutations were found in 5 out of 27 (18.5%) of cases. Four patients with SF1 mutations presented with the similar phenotype of mild gonadal dysgenesis, severe underandrogenization, and absent Müllerian structures. Of these, two patients harbored missense mutations within the DNA-binding region of SF1 (p.C33S, p.R84H), one patient had a nonsense mutation (p.Y138X) and one patient had a frameshift mutation (c.1277dupT) predicted to disrupt RNA stability or protein function. One additional patient ([c.424_427dupCCCA]+[p.G146A]) displayed a more marked phenotype of severe gonadal dysgenesis...

‣ Two mouse retinal degenerations caused by missense mutations in the beta-subunit of rod cGMP phosphodiesterase gene

Chang, B.; Hawes, N.L.; Pardue, M. T.; German, A.M.; Hurd, R.E.; Davisson, M.T.; Nusinowitz, S.; Rengarajan, K.; Boyd, A.P.; Starr, S.S.; Chaudhury, R.C.; Nickerson, J.M.; Heckenlively, J.R.; Boatright, J.H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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We report the chromosomal localization, mutant gene identification, ophthalmic appearance, histology, and functional analysis of two new hereditary mouse models of retinal degeneration not having the Pde6brd1 (“r”, “rd”, or “rodless”) mutation. One strain harbors an autosomal recessive mutation that maps to mouse chromosome 5. Sequence analysis showed that the retinal degeneration is caused by a missense point mutation in exon 13 of the beta-subunit of the rod cGMP phosphodiesterase (β-PDE) gene (Pde6b). The gene symbol for this strain was set as Pde6brd10, abbreviated rd10 hereafter. Mice homozygous for the rd10 mutation showed histological changes at postnatal day 16 (P16) of age and sclerotic retinal vessels at four weeks of age, consistent with retinal degeneration. Retinal sections were highly positive for TUNEL and activated caspase-3 immunoreactivity, specifically in the outer nuclear layer (ONL). ERGs were never normal, but rod and cone ERG a- and b-waves were easily measured at P18 and steadily declined over 90% by two months of age. Protein extracts from rd10 retinas were positive for β-PDE immunoreactivity starting at about the same time as wild type (P10), though signal averaged less than 40% of wild type. Interestingly...

‣ Missense mutations that cause Van der Woude syndrome and popliteal pterygium syndrome affect the DNA-binding and transcriptional activation functions of IRF6

Little, Hayley J.; Rorick, Nicholas K.; Su, Ling-I; Baldock, Clair; Malhotra, Saimon; Jowitt, Tom; Gakhar, Lokesh; Subramanian, Ramaswamy; Schutte, Brian C.; Dixon, Michael J.; Shore, Paul
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
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Cleft lip and cleft palate (CLP) are common disorders that occur either as part of a syndrome, where structures other than the lip and palate are affected, or in the absence of other anomalies. Van der Woude syndrome (VWS) and popliteal pterygium syndrome (PPS) are autosomal dominant disorders characterized by combinations of cleft lip, CLP, lip pits, skin-folds, syndactyly and oral adhesions which arise as the result of mutations in interferon regulatory factor 6 (IRF6). IRF6 belongs to a family of transcription factors that share a highly conserved N-terminal, DNA-binding domain and a less well-conserved protein-binding domain. To date, mutation analyses have suggested a broad genotype–phenotype correlation in which missense and nonsense mutations occurring throughout IRF6 may cause VWS; in contrast, PPS-causing mutations are highly associated with the DNA-binding domain, and appear to preferentially affect residues that are predicted to interact directly with the DNA. Nevertheless, this genotype–phenotype correlation is based on the analysis of structural models rather than on the investigation of the DNA-binding properties of IRF6. Moreover, the effects of mutations in the protein interaction domain have not been analysed. In the current investigation...

‣ A Missense LAMB2 Mutation Causes Congenital Nephrotic Syndrome by Impairing Laminin Secretion

Chen, Ying Maggie; Kikkawa, Yamato; Miner, Jeffrey H.
Fonte: American Society of Nephrology Publicador: American Society of Nephrology
Tipo: Artigo de Revista Científica
Publicado em /05/2011 Português
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Laminin β2 is a component of laminin-521, which is an important constituent of the glomerular basement membrane (GBM). Null mutations in laminin β2 (LAMB2) cause Pierson syndrome, a severe congenital nephrotic syndrome with ocular and neurologic defects. In contrast, patients with LAMB2 missense mutations, such as R246Q, can have less severe extrarenal defects but still exhibit congenital nephrotic syndrome. To investigate how such missense mutations in LAMB2 cause proteinuria, we generated three transgenic lines of mice in which R246Q-mutant rat laminin β2 replaced the wild-type mouse laminin β2 in the GBM. These transgenic mice developed much less severe proteinuria than their nontransgenic Lamb2-deficient littermates; the level of proteinuria correlated inversely with R246Q-LAMB2 expression. At the onset of proteinuria, expression and localization of proteins associated with the slit diaphragm and foot processes were normal, and there were no obvious ultrastructural abnormalities. Low transgene expressors developed heavy proteinuria, foot process effacement, GBM thickening, and renal failure by 3 months, but high expressors developed only mild proteinuria by 9 months. In vitro studies demonstrated that the R246Q mutation results in impaired secretion of laminin. Taken together...

‣ Mutations in the Alpha 1,2-Mannosidase Gene, MAN1B1, Cause Autosomal-Recessive Intellectual Disability

Rafiq, Muhammad Arshad; Kuss, Andreas W.; Puettmann, Lucia; Noor, Abdul; Ramiah, Annapoorani; Ali, Ghazanfar; Hu, Hao; Kerio, Nadir Ali; Xiang, Yong; Garshasbi, Masoud; Khan, Muzammil Ahmad; Ishak, Gisele E.; Weksberg, Rosanna; Ullmann, Reinhard; Tzs
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 15/07/2011 Português
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We have used genome-wide genotyping to identify an overlapping homozygosity-by-descent locus on chromosome 9q34.3 (MRT15) in four consanguineous families affected by nonsyndromic autosomal-recessive intellectual disability (NS-ARID) and one in which the patients show additional clinical features. Four of the families are from Pakistan, and one is from Iran. Using a combination of next-generation sequencing and Sanger sequencing, we have identified mutations in the gene MAN1B1, encoding a mannosyl oligosaccharide, alpha 1,2-mannosidase. In one Pakistani family, MR43, a homozygous nonsense mutation (RefSeq number NM_016219.3: c.1418G>A [p.Trp473∗]), segregated with intellectual disability and additional dysmorphic features. We also identified the missense mutation c. 1189G>A (p.Glu397Lys; RefSeq number NM_016219.3), which segregates with NS-ARID in three families who come from the same village and probably have shared inheritance. In the Iranian family, the missense mutation c.1000C>T (p.Arg334Cys; RefSeq number NM_016219.3) also segregates with NS-ARID. Both missense mutations are at amino acid residues that are conserved across the animal kingdom, and they either reduce kcat by ∼1300-fold or disrupt stable protein expression in mammalian cells. MAN1B1 is one of the few NS-ARID genes with an elevated mutation frequency in patients with NS-ARID from different populations.

‣ Genetic Testing for TMEM154 Mutations Associated with Lentivirus Susceptibility in Sheep

Heaton, Michael P.; Kalbfleisch, Theodore S.; Petrik, Dustin T.; Simpson, Barry; Kijas, James W.; Clawson, Michael L.; Chitko-McKown, Carol G.; Harhay, Gregory P.; Leymaster, Kreg A.;
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 11/02/2013 Português
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In sheep, small ruminant lentiviruses cause an incurable, progressive, lymphoproliferative disease that affects millions of animals worldwide. Known as ovine progressive pneumonia virus (OPPV) in the U.S., and Visna/Maedi virus (VMV) elsewhere, these viruses reduce an animal’s health, productivity, and lifespan. Genetic variation in the ovine transmembrane protein 154 gene (TMEM154) has been previously associated with OPPV infection in U.S. sheep. Sheep with the ancestral TMEM154 haplotype encoding glutamate (E) at position 35, and either form of an N70I variant, were highly-susceptible compared to sheep homozygous for the K35 missense mutation. Our current overall aim was to characterize TMEM154 in sheep from around the world to develop an efficient genetic test for reduced susceptibility. The average frequency of TMEM154 E35 among 74 breeds was 0.51 and indicated that highly-susceptible alleles were present in most breeds around the world. Analysis of whole genome sequences from an international panel of 75 sheep revealed more than 1,300 previously unreported polymorphisms in a 62 kb region containing TMEM154 and confirmed that the most susceptible haplotypes were distributed worldwide. Novel missense mutations were discovered in the signal peptide (A13V) and the extracellular domains (E31Q...

‣ Transcriptional regulation of the ABCC6 gene and the background of impaired function of missense disease-causing mutations

Arányi, Tamás; Bacquet, Caroline; de Boussac, Hugues; Ratajewski, Marcin; Pomozi, Viola; Fülöp, Krisztina; Brampton, Christopher N.; Pulaski, Lukasz; Saux, Olivier Le; Váradi, András
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 11/03/2013 Português
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The human ATP-binding cassette family C member 6 (ABCC6) gene encodes an ABC transporter protein expressed primarily in the liver and to a lesser extent in the kidneys and the intestines. We review here the mechanisms of this restricted tissue-specific expression and the role of hepatocyte nuclear factor 4α which is responsible for the expression pattern. Detailed analyses uncovered further regulators of the expression of the gene pointing to an intronic primate-specific regulator region, an activator of the expression of the gene by binding CCAAT/enhancer-binding protein beta, which interacts with other proteins acting in the proximal promoter. This regulatory network is affected by various environmental stimuli including oxidative stress and the extracellular signal-regulated protein kinases 1 and 2 pathway. We also review here the structural and functional consequences of disease-causing missense mutations of ABCC6. A significant clustering of the missense disease-causing mutations was found at the domain–domain interfaces. This clustering means that the domain contacts are much less permissive to amino acid replacements than the rest of the protein. We summarize the experimental methods resulting in the identification of mutants with preserved transport activity but failure in intracellular targeting. These mutants are candidates for functional rescue by chemical chaperons. The results of such research can provide the basis of future allele-specific therapy of ABCC6-mediated disorders like pseudoxanthoma elasticum or the generalized arterial calcification in infancy.

‣ MMuFLR: missense mutation and frameshift location reporter

Rathe, Susan K.; Johnson, James E.; Silverstein, Kevin A.T.; Erdmann, Jesse J.; Watson, Adrienne L.; Popescu, Flavia E.; Ohlfest, John R.; Largaespada, David A.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
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Motivation: Cancer researchers seeking immunotherapy targets in cancer cells need tools to locate highly expressed proteins unique to cancer cells. Missense mutation and frameshift location reporter (MMuFLR), a Galaxy-based workflow, analyzes next-generation sequencing paired read RNA-seq output to reliably identify small frameshift mutations and missense mutations in highly expressed protein-coding genes. MMuFLR ignores known SNPs, low quality reads and poly-A/T sequences. For each frameshift and missense mutation identified, MMuFLR provides the location and sequence of the amino acid substitutions in the novel protein candidates for direct input into epitope evaluation tools.

‣ Missense dopamine transporter mutations associate with adult parkinsonism and ADHD

Hansen, Freja H.; Skjørringe, Tina; Yasmeen, Saiqa; Arends, Natascha V.; Sahai, Michelle A.; Erreger, Kevin; Andreassen, Thorvald F.; Holy, Marion; Hamilton, Peter J.; Neergheen, Viruna; Karlsborg, Merete; Newman, Amy H.; Pope, Simon; Heales, Simon J.R.;
Fonte: American Society for Clinical Investigation Publicador: American Society for Clinical Investigation
Tipo: Artigo de Revista Científica
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Parkinsonism and attention deficit hyperactivity disorder (ADHD) are widespread brain disorders that involve disturbances of dopaminergic signaling. The sodium-coupled dopamine transporter (DAT) controls dopamine homeostasis, but its contribution to disease remains poorly understood. Here, we analyzed a cohort of patients with atypical movement disorder and identified 2 DAT coding variants, DAT-Ile312Phe and a presumed de novo mutant DAT-Asp421Asn, in an adult male with early-onset parkinsonism and ADHD. According to DAT single-photon emission computed tomography (DAT-SPECT) scans and a fluoro-deoxy-glucose-PET/MRI (FDG-PET/MRI) scan, the patient suffered from progressive dopaminergic neurodegeneration. In heterologous cells, both DAT variants exhibited markedly reduced dopamine uptake capacity but preserved membrane targeting, consistent with impaired catalytic activity. Computational simulations and uptake experiments suggested that the disrupted function of the DAT-Asp421Asn mutant is the result of compromised sodium binding, in agreement with Asp421 coordinating sodium at the second sodium site. For DAT-Asp421Asn, substrate efflux experiments revealed a constitutive, anomalous efflux of dopamine, and electrophysiological analyses identified a large cation leak that might further perturb dopaminergic neurotransmission. Our results link specific DAT missense mutations to neurodegenerative early-onset parkinsonism. Moreover...

‣ Prediction of Missense Mutation Functionality Depends on both the Algorithm and Sequence Alignment Employed

Hicks, Stephanie; Wheeler, David A.; Plon, Sharon E.; Kimmel, Marek
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Multiple algorithms are used to predict the impact of missense mutations on protein structure and function using algorithm-generated sequence alignments or manually curated alignments. We compared the accuracy with native alignment of SIFT, Align-GVGD, PolyPhen-2 and Xvar when generating functionality predictions of well characterized missense mutations (n = 267) within the BRCA1, MSH2, MLH1 and TP53 genes. We also evaluated the impact of the alignment employed on predictions from these algorithms (except Xvar) when supplied the same four alignments including alignments automatically generated by (1) SIFT, (2) Polyphen-2, (3) Uniprot, and (4) a manually curated alignment tuned for Align-GVGD. Alignments differ in sequence composition and evolutionary depth. Data-based receiver operating characteristic curves employing the native alignment for each algorithm result in area under the curve of 78-79% for all four algorithms. Predictions from the PolyPhen-2 algorithm were least dependent on the alignment employed. In contrast, Align-GVGD predicts all variants neutral when provided alignments with a large number of sequences. Of note, algorithms make different predictions of variants even when provided the same alignment and do not necessarily perform best using their own alignment. Thus...

‣ Increased Incidence of Mitochondrial Cytochrome C Oxidase 1 Gene Mutations in Patients with Primary Ovarian Insufficiency

Zhen, Xiumei; Wu, Bailin; Wang, Jian; Lu, Cuiling; Gao, Huafang; Qiao, Jie
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 30/07/2015 Português
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Primary ovarian insufficiency (POI), also known as premature ovarian failure (POF), is defined as more than six months of cessation of menses before the age of 40 years, with two serum follicle stimulating hormone (FSH) levels (at least 1 month apart) falling in the menopause range. The cause of POI remains undetermined in the majority of cases, although some studies have reported increased levels of reactive oxygen species (ROS) in idiopathic POF. The role of mitochondrial DNA in the pathogenesis of POI has not been studied extensively. This aim of this study was to uncover underlying mitochondrial genetic defects in patients with POI. The entire region of the mitochondrial genome was amplified in subjects with idiopathic POI (n=63) and age-matched healthy female controls (n=63) using nine pair sets of primers, followed by screening of the mitochondrial genome using an Illumina MiSeq. We identified a total of 96 non-synonymous mitochondrial variations in POI patients and 93 non-synonymous variations in control subjects. Of these, 21 (9 in POI and 12 in control) non-synonymous variations had not been reported previously. Eight mitochondrial cytochrome coxidase 1 (MT-CO1) missense variants were identified in POI patients, whereas only four missense mutations were observed in controls. A high incidence of MT-CO1 missense variants were identified in POI patients compared with controls...

‣ Increased Incidence of Mitochondrial Cytochrome C Oxidase 1 Gene Mutations in Patients with Primary Ovarian Insufficiency

Zhen, Xiumei; Wu, Bailin; Wang, Jian; Lu, Cuiling; Gao, Huafang; Qiao, Jie
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
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Primary ovarian insufficiency (POI), also known as premature ovarian failure (POF), is defined as more than six months of cessation of menses before the age of 40 years, with two serum follicle stimulating hormone (FSH) levels (at least 1 month apart) falling in the menopause range. The cause of POI remains undetermined in the majority of cases, although some studies have reported increased levels of reactive oxygen species (ROS) in idiopathic POF. The role of mitochondrial DNA in the pathogenesis of POI has not been studied extensively. This aim of this study was to uncover underlying mitochondrial genetic defects in patients with POI. The entire region of the mitochondrial genome was amplified in subjects with idiopathic POI (n=63) and age-matched healthy female controls (n=63) using nine pair sets of primers, followed by screening of the mitochondrial genome using an Illumina MiSeq. We identified a total of 96 non-synonymous mitochondrial variations in POI patients and 93 non-synonymous variations in control subjects. Of these, 21 (9 in POI and 12 in control) non-synonymous variations had not been reported previously. Eight mitochondrial cytochrome coxidase 1 (MT-CO1) missense variants were identified in POI patients, whereas only four missense mutations were observed in controls. A high incidence of MT-CO1 missense variants were identified in POI patients compared with controls...

‣ Genetic testing for TMEM154 mutations associated with lentivirus susceptibility in sheep

Heaton, M.; Hiendleder, S.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
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In sheep, small ruminant lentiviruses cause an incurable, progressive, lymphoproliferative disease that affects millions of animals worldwide. Known as ovine progressive pneumonia virus (OPPV) in the U.S., and Visna/Maedi virus (VMV) elsewhere, these viruses reduce an animal’s health, productivity, and lifespan. Genetic variation in the ovine transmembrane protein 154 gene (TMEM154) has been previously associated with OPPV infection in U.S. sheep. Sheep with the ancestral TMEM154 haplotype encoding glutamate (E) at position 35, and either form of an N70I variant, were highly-susceptible compared to sheep homozygous for the K35 missense mutation. Our current overall aim was to characterize TMEM154 in sheep from around the world to develop an efficient genetic test for reduced susceptibility. The average frequency of TMEM154 E35 among 74 breeds was 0.51 and indicated that highly-susceptible alleles were present in most breeds around the world. Analysis of whole genome sequences from an international panel of 75 sheep revealed more than 1,300 previously unreported polymorphisms in a 62 kb region containing TMEM154 and confirmed that the most susceptible haplotypes were distributed worldwide. Novel missense mutations were discovered in the signal peptide (A13V) and the extracellular domains (E31Q...