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‣ 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 Formato: 241-247
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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...

‣ Molecular analysis of mutations in DNA polymerase η in xeroderma pigmentosum-variant patients

Broughton, Bernard C.; Cordonnier, Agnes; Kleijer, Wim J.; Jaspers, Nicolaas G. J.; Fawcett, Heather; Raams, Anja; Garritsen, Victor H.; Stary, Anne; Avril, Marie-Françoise; Boudsocq, François; Masutani, Chikahide; Hanaoka, Fumio; Fuchs, Robert P.; Sara
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
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Xeroderma pigmentosum variant (XP-V) cells are deficient in their ability to synthesize intact daughter DNA strands after UV irradiation. This deficiency results from mutations in the gene encoding DNA polymerase η, which is required for effecting translesion synthesis (TLS) past UV photoproducts. We have developed a simple cellular procedure to identify XP-V cell strains, and have subsequently analyzed the mutations in 21 patients with XP-V. The 16 mutations that we have identified fall into three categories. Many of them result in severe truncations of the protein and are effectively null alleles. However, we have also identified five missense mutations located in the conserved catalytic domain of the protein. Extracts of cells falling into these two categories are defective in the ability to carry out TLS past sites of DNA damage. Three mutations cause truncations at the C terminus such that the catalytic domains are intact, and extracts from these cells are able to carry out TLS. From our previous work, however, we anticipate that protein in these cells will not be localized in the nucleus nor will it be relocalized into replication foci during DNA replication. The spectrum of both missense and truncating mutations is markedly skewed toward the N-terminal half of the protein. Two of the missense mutations are predicted to affect the interaction with DNA...

‣ Calcium-sensing receptor mutations in familial benign hypercalcemia and neonatal hyperparathyroidism.

Pearce, S H; Trump, D; Wooding, C; Besser, G M; Chew, S L; Grant, D B; Heath, D A; Hughes, I A; Paterson, C R; Whyte, M P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1995 Português
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Familial benign hypercalcemia (FBH) and neonatal hyperparathyroidism (NHPT) are disorders of calcium homeostasis that are associated with missense mutations of the calcium-sensing receptor (CaR). We have undertaken studies to characterize such CaR mutations in FBH and NHPT and to explore methods for their more rapid detection. Nine unrelated kindreds (39 affected, 32 unaffected members) with FBH and three unrelated children with sporadic NHPT were investigated for mutations in the 3,234-bp coding region of the CaR gene by DNA sequencing. Six novel heterozygous (one nonsense and five missense) mutations were identified in six of the nine FBH kindreds, and two de novo heterozygous missense mutations and one homozygous frame-shift mutation were identified in the three children with NHPT. Our results expand the phenotypes associated with CaR mutations to include sporadic NHPT. Single-stranded conformational polymorphism analysis was found to be a sensitive and specific mutational screening method that detected > 85% of these CaR gene mutations. The single-stranded conformational polymorphism identification of CaR mutations may help in the distinction of FBH from mild primary hyperparathyroidism which can be clinically difficult. Thus, the results of our study will help to supplement the clinical evaluation of some hypercalcemic patients and to elucidate further the structure-function relationships of the CaR.

‣ Common low-density lipoprotein receptor mutations in the French Canadian population.

Leitersdorf, E; Tobin, E J; Davignon, J; Hobbs, H H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1990 Português
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Familial hypercholesterolemia (FH) has a frequency of 0.2% in most populations of the world. In selected populations such as the Afrikaners in South Africa, the Christian Lebanese, and the French Canadians, the disease is more frequent due to the founder effect. Previous studies demonstrated that a single mutation at the LDL receptor locus, the so-called French Canadian deletion, makes up 60% of the mutant genes responsible for FH in the French Canadian population. In this study, efforts were directed to determine if there were other common LDL receptor mutations in this population. Three missense mutations were identified and each mutation was reproduced and expressed in vitro. Two of the three mutations result in the production of an LDL receptor protein that is not processed to its mature form at a normal rate. Molecular assays were developed to detect the mutations directly, and the LDL receptor genes of 130 French Canadian FH heterozygotes were screened for the presence of the three missense mutations as well as two deletions. LDL receptor mutations were detected in 76% of individuals and 14% had one of the three missense mutations.

‣ Menin Missense Mutants Associated with Multiple Endocrine Neoplasia Type 1 Are Rapidly Degraded via the Ubiquitin-Proteasome Pathway

Yaguchi, Hiroko; Ohkura, Naganari; Takahashi, Maho; Nagamura, Yuko; Kitabayashi, Issay; Tsukada, Toshihiko
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /08/2004 Português
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MEN1 is a tumor suppressor gene that is responsible for multiple endocrine neoplasia type 1 (MEN1) and that encodes a 610-amino-acid protein, called menin. While the majority of germ line mutations identified in MEN1 patients are frameshift and nonsense mutations resulting in truncation of the menin protein, various missense mutations have been identified whose effects on menin activity are unclear. For this study, we analyzed a series of menin proteins with single amino acid alterations and found that all of the MEN1-causing missense mutations tested led to greatly diminished levels of the affected proteins in comparison with wild-type and benign polymorphic menin protein levels. We demonstrate here that the reduced levels of the mutant proteins are due to rapid degradation via the ubiquitin-proteasome pathway. Furthermore, the mutants, but not wild-type menin, interact both with the molecular chaperone Hsp70 and with the Hsp70-associated ubiquitin ligase CHIP, and the overexpression of CHIP promotes the ubiquitination of the menin mutants in vivo. These findings reveal that MEN1-causing missense mutations lead to a loss of function of menin due to enhanced proteolytic degradation, which may be a common mechanism for inactivating tumor suppressor gene products in familial cancer.

‣ The site of a missense mutation in the extracellular Ig or FN domains of L1CAM influences infant mortality and the severity of X linked hydrocephalus.

Michaelis, R C; Du, Y Z; Schwartz, C E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1998 Português
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The L1 cell adhesion molecule (L1CAM) plays an important role in axon growth, fasciculation, and neural migration. Mutations in the L1CAM gene produce a phenotype characterised by X linked hydrocephalus, mental retardation, spastic paraplegia, adducted thumbs, and agenesis of the corpus callosum. We have conducted a detailed analysis of the phenotypic effects of missense mutations in the extracellular portion of L1CAM, following a study that differentiated between "key" amino acid residues critical for maintaining the conformation of the extracellular immunoglobulin type C-like (Ig) or fibronectin type III-like (FN) domains and surface residues of less certain significance. We have analysed the data from 71 published cases and seven patients whose mutations were detected in our laboratory to determine if the site of a missense mutation in the Ig or FN domains correlated with the severity of hydrocephalus, presence of adducted thumbs, or survival past infancy. Mutations affecting the key residues in either type of domain were more likely to produce a phenotype with severe hydrocephalus, adducted thumbs, and lifespan less than one year than were mutations affecting surface residues. In addition, mutations affecting the FN domains were more likely than those affecting Ig domains to produce a phenotype with severe hydrocephalus...

‣ p63 Gene Mutations in EEC Syndrome, Limb-Mammary Syndrome, and Isolated Split Hand–Split Foot Malformation Suggest a Genotype-Phenotype Correlation

van Bokhoven, Hans; Hamel, Ben C. J.; Bamshad, Mike; Sangiorgi, Eugenio; Gurrieri, Fiorella; Duijf, Pascal H. G.; Vanmolkot, Kaate R. J.; van Beusekom, Ellen; van Beersum, Sylvia E. C.; Celli, Jacopo; Merkx, Gerard F. M.; Tenconi, Romano; Fryns, Jean P
Fonte: The American Society of Human Genetics Publicador: The American Society of Human Genetics
Tipo: Artigo de Revista Científica
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p63 mutations have been associated with EEC syndrome (ectrodactyly, ectodermal dysplasia, and cleft lip/palate), as well as with nonsyndromic split hand–split foot malformation (SHFM). We performed p63 mutation analysis in a sample of 43 individuals and families affected with EEC syndrome, in 35 individuals affected with SHFM, and in three families with the EEC-like condition limb-mammary syndrome (LMS), which is characterized by ectrodactyly, cleft palate, and mammary-gland abnormalities. The results differed for these three conditions. p63 gene mutations were detected in almost all (40/43) individuals affected with EEC syndrome. Apart from a frameshift mutation in exon 13, all other EEC mutations were missense, predominantly involving codons 204, 227, 279, 280, and 304. In contrast, p63 mutations were detected in only a small proportion (4/35) of patients with isolated SHFM. p63 mutations in SHFM included three novel mutations: a missense mutation (K193E), a nonsense mutation (Q634X), and a mutation in the 3′ splice site for exon 5. The fourth SHFM mutation (R280H) in this series was also found in a patient with classical EEC syndrome, suggesting partial overlap between the EEC and SHFM mutational spectra. The original family with LMS (van Bokhoven et al. 1999) had no detectable p63 mutation...

‣ Mutations in NPC1 Highlight a Conserved NPC1-Specific Cysteine-Rich Domain

Greer, W. L.; Dobson, M. J.; Girouard, G. S.; Byers, D. M.; Riddell, D. C.; Neumann, P. E.
Fonte: The American Society of Human Genetics Publicador: The American Society of Human Genetics
Tipo: Artigo de Revista Científica
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Niemann-Pick type II disease is an autosomal recessive disorder characterized by a defect in intracellular trafficking of sterols. We have determined the intron/exon boundaries of eight exons from the conserved 3′ portion of NPC1, the gene associated with most cases of the disease. SSCP analyses were designed for these exons and were used to identify the majority of mutations in 13 apparently unrelated families. Thirteen mutations were found, accounting for 19 of the 26 alleles. These mutations included eight different missense mutations (including one reported by Greer et al. [1998]), one 4-bp and two 2-bp deletions that generate premature stop codons, and two intronic mutations that are predicted to alter splicing. Two of the missense mutations were present in predicted transmembrane (TM) domains. Clustering of these and other reported NPC1 mutations in the carboxy-terminal third of the protein indicates that screening of these exons, by means of the SSCP analyses reported here, will detect most mutations. The carboxy-terminal half of the Npc1 protein shares amino acid similarity with the TM domains of the morphogen receptor Patched, with the largest stretch of unrelated sequence lying between two putative TM spans. Alignment of this portion of the human Npc1 protein sequence with Npc1-related sequences from mouse...

‣ Spectrum of mutations in the OCRL1 gene in the Lowe oculocerebrorenal syndrome.

Lin, T; Orrison, B M; Leahey, A M; Suchy, S F; Bernard, D J; Lewis, R A; Nussbaum, R L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1997 Português
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The oculocerebrorenal syndrome of Lowe (OCRL) is a multisystem disorder characterized by congenital cataracts, mental retardation, and renal Fanconi syndrome. The OCRL1 gene, which, when mutated, is responsible for OCRL, encodes a 105-kD Golgi protein with phosphatidylinositol (4,5)bisphosphate (PtdIn[4,5]P2) 5-phosphatase activity. We have examined the OCRL1 gene in 12 independent patients with OCRL and have found 11 different mutations. Six were nonsense mutations, and one a deletion of one or two nucleotides that leads to frameshift and premature termination. In one, a 1.2-kb genomic deletion of exon 14 was identified. In four others, missense mutations or the deletion of a single codon were found to involve amino acid residues known to be highly conserved among proteins with PtdIns(4,5)P2 5-phosphatase activity. All patients had markedly reduced PtdIns(4,5)P2 5-phosphatase activity in their fibroblasts, whereas the ocrl1 protein was detectable by immunoblotting in some patients with either missense mutations or a codon deletion but was not detectable in those with premature termination mutations. These results confirm and extend our previous observation that the OCRL phenotype results from loss of function of the ocrl1 protein and that mutations are generally heterogeneous. Missense mutations that abolish enzyme activity but not expression of the protein will be useful for studying structure-function relationships in PtdIns(4...

‣ Identification and expression of eight novel mutations among non-Jewish patients with Canavan disease.

Kaul, R.; Gao, G. P.; Matalon, R.; Aloya, M.; Su, Q.; Jin, M.; Johnson, A. B.; Schutgens, R. B.; Clarke, J. T.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1996 Português
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Canavan disease is inherited as an autosomal recessive trait that is caused by the deficiency of aspartoacylase (ASPA). The majority of patients with Canavan disease are from an Ashkenazi Jewish background. Mutations in ASPA that lead to loss of enzymatic activity have been identified, and E285A and Y231X are the two predominant mutations that account for 97% of the mutant chromosomes in Ashkenazi Jewish patients. The current study was aimed at finding the molecular basis of Canavan disease in 25 independent patients of non-Jewish background. Eight novel and three previously characterized mutations accounted for 80% (40/50) of mutant chromosomes. The A305E missense mutation accounted for 48% (24/50) of mutant chromosomes in patients of western European descent, while the two predominant Jewish mutations each accounted for a single mutant chromosome. The eight novel mutations identified included 1- and 4-bp deletions (32 deltaT and 876 deltaAGAA, respectively) and I16T, G27R, D114E, G123E, C152Y, and R168C missense mutations. The homozygous 32 deltaT deletion was identified in the only known patient of African-American origin with Canavan disease. The heterozygosity for 876 deltaAGAA mutation was identified in three independent patients from England. Six single-base changes leading to missense mutations were identified in patients from Turkey (D114E...

‣ Mutations and Polymorphisms in GUSB Gene in Mucopolysaccharidosis VII (Sly Syndrome)

Tomatsu, Shunji; Montaño, Adriana M.; Dung, Vu Chi; Grubb, Jeffrey H.; Sly, William S.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/2009 Português
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Mucopolysaccharidosis VII (MPS VII; Sly syndrome) is an autosomal recessive disorder caused by a deficiency of β-glucuronidase (GUS, EC 3.2.1.31; GUSB). GUS is required to degrade glycosaminoglycans (GAGs), including heparan sulfate (HS), dermatan sulfate (DS), and chondroitin-4,6-sulfate (CS). Accumulation of undegraded GAGs in lysosomes of affected tissues leads to mental retardation, short stature, hepatosplenomegaly, bone dysplasia, and hydrops fetalis. We summarize information on the 49 unique, disease-causing mutations determined so far in the GUS gene, including nine novel mutations (eight missense and one splice-site). This heterogeneity in GUS gene mutations contributes to the extensive clinical variability among patients with MPS VII. One pseudodeficiency allele, one polymorphism causing an amino acid change, and one silent variant in the coding region are also described. Among the 103 analyzed mutant alleles, missense mutations accounted for 78.6%; nonsense mutations, 12.6%; deletions, 5.8%; and splice-site mutations, 2.9%. Transitional mutations at CpG dinucleotides made up 40.8% of all the described mutations. The five most frequent mutations (accounting for 44/103 alleles) were exonic point mutations, p.L176F, p.R357X...

‣ The genotypic and phenotypic spectrum of pyridoxine-dependent epilepsy due to mutations in ALDH7A1

Scharer, Gunter; Brocker, Chad; Vasiliou, Vasilis; Creadon-Swindell, Geralyn; Gallagher, Renata C.; Spector, Elaine; Van Hove, Johan L. K.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Pyridoxine-dependent epilepsy is a disorder associated with severe seizures that may be caused by deficient activity of α-aminoadipic semialdehyde dehydrogenase, encoded by the ALDH7A1 gene, with accumulation of α-aminoadipic semialdehyde and piperideine-6-carboxylic acid. The latter reacts with pyridoxal-phosphate, explaining the effective treatment with pyridoxine. We report the clinical phenotype of three patients, their mutations and those of 12 additional patients identified in our clinical molecular laboratory. There were six missense, one nonsense, and five splice-site mutations, and two small deletions. Mutations c.1217_1218delAT, I431F, IVS-1(+2)T>G, IVS-2(+1)G>A, and IVS-12(+1)G>A are novel. Some disease alleles were recurring: E399Q (eight times), G477R (six times), R82X (two times), and c.1217_1218delAT (two times). A systematic review of mutations from the literature indicates that missense mutations cluster around exons 14, 15, and 16. Nine mutations represent 61% of alleles. Molecular modeling of missense mutations allows classification into three groups: those that affect NAD+binding or catalysis, those that affect the substrate binding site, and those that affect multimerization. There are three clinical phenotypes: patients with complete seizure control with pyridoxine and normal developmental outcome (group 1) including our first patient; patients with complete seizure control with pyridoxine but with developmental delay (group 2)...

‣ Transglutaminase-1 (TGM1) Gene Mutations in Autosomal Recessive Congenital Ichthyosis: Summary of Mutations (Including 23 Novel) and Modeling of TGase-1

Herman, Matthew L.; Farasat, Sharifeh; Steinbach, Peter J.; Wei, Ming-Hui; Toure, Ousmane; Fleckman, Philip; Blake, Patrick; Bale, Sherri J.; Toro, Jorge R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/2009 Português
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Autosomal recessive congenital ichthyosis (ARCI) is a heterogeneous group of rare cornification diseases. Germline mutations in TGM1 are the most common cause of ARCI in the US. TGM1 encodes for the TGase-1 enzyme that functions in the formation of the cornified cell envelope. We review the clinical manifestations as well as the molecular genetics of ARCI. In addition, we characterized 115 TGM1 mutations reported in 234 patients from diverse racial and ethnic backgrounds (Caucasion Americans, Norwegians, Swedish, Finnish, German, Swiss, French, Italian, Dutch, Portuguese, Hispanics, Iranian, Tunisian, Moroccan, Egyptian, Afghani, Hungarian, African-Americans, Korean, Japanese and South African). We report 23 novel mutations: 71 (62%) missense; twenty (17%) nonsense; nine (8%) deletion; eight (7%) splice-site and seven (6%) insertion. The c.877-2A>G was the most commonly reported TGM1 mutation accounting for 34 % (147/435) of all TGM1 mutant alleles reported to date. It had been shown that this mutation is common among North American and Norwegian patients due to a founder effect. Thirty-one percent (36/115) of all mutations and 41% (29/71) of missense mutations occurred in arginine residues in TGase-1. Forty-nine percent (35/71) of missense mutations were within CpG dinucleotides...

‣ Assessment of TP53 Mutations in Benign and Malignant Salivary Gland Neoplasms

Gomes, Carolina Cavaliéri; Diniz, Marina Gonçalves; Orsine, Lissur Azevedo; Duarte, Alessandra Pires; Fonseca-Silva, Thiago; Conn, Brendan I.; De Marco, Luiz; Pereira, Cláudia Maria; Gomez, Ricardo Santiago
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 19/07/2012 Português
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Despite advances in the understanding of the pathogenesis of salivary gland neoplasms (SGN), the molecular pathways associated with enhanced tumor growth and cell survival remain to be established. The aim of the present study was to investigate whether TP53 mutations are relevant to SGN pathogenesis and if they impact on p53 protein expression. The study included 18 benign and 18 malignant SGN samples. Two polymorphic microsatellite markers at the TP53 genetic locus were chosen to assess loss of heterozygosity (LOH) in the samples that had matched normal DNA. The TP53 exons 2–11 were amplified by PCR, and all of the products were sequenced. Reverse transcription-PCR of the TP53 open reading frame (ORF) was carried out in the samples that had fresh tissue available, and immunohistochemistry for the p53 protein was performed in all samples. TP53 LOH was only found in two pleomorphic adenomas. We found two missense mutations in exon 7 (one in a pleomorphic adenoma and the other in a polymorphous low grade adenocarcinoma), another in exon 8 (in a carcinoma ex pleomorphic adenoma) and a fourth missense mutation in exon 10 (in a mucoepidermoid carcinoma). In addition, a nonsense mutation was found in exon 8 of an adenoid cystic carcinoma. Several intronic and exonic SNPs were detected. Although almost all of the malignant samples were immunopositive for p53...

‣ Novel sequence variants and common recurrent polymorphisms of BRCA2 in Sri Lankan breast cancer patients and a family with BRCA1 mutations

DE SILVA, SUMADEE; TENNEKOON, KAMANI H.; KARUNANAYAKE, ERIC H.; DE SILVA, WASANTHI; AMARASINGHE, INDRANI; ANGUNAWELA, PREETHIKA
Fonte: D.A. Spandidos Publicador: D.A. Spandidos
Tipo: Artigo de Revista Científica
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We previously reported BRCA1 mutations and sequence variants in Sri Lankan breast cancer patients. Mutations and sequence variants of the BRCA2 gene were studied in 149 study participants from the same cohort. There were 55 familial and 54 sporadic breast cancer patients, 20 at-risk individuals and 20 healthy controls. Direct sequencing (exon 11) and sequencing of abnormal bands after screening with single-strand conformation polymorphism (remaining exons) were used to detect mutations and sequence variants. Twenty-three sequence variants were found in the BRCA2 gene. Two novel pathogenic frame-shift additions resulting in a premature stop codon (c.2403 insA/exon 11, c.2667 insT/exon 11) were identified. Possibly pathogenic two novel missense mutations (c.1191 A>C/exon 10, c.5695 A>C/exon 11) one novel intronic variant (IVS15-21 insTT), four novel silent mutations (c.969 C>T/exon 9, c.1353 C>T/exon 10, c.2766 A>C/exon 11 and c.7452 A>G/exon 14) and one novel missense mutation (c.971 C>G/exon 9) were observed. One previously reported possibly pathogenic intronic variant (IVS81 G>C) and several previously reported silent mutations, missense mutations, and one 5′ UTR polymorphism were detected. Pathogenic and possibly pathogenic mutations were more frequent in the BRCA2 gene among Sri Lankan familial breast cancer patients when compared to our previous findings for the BRCA1 gene.

‣ Novel mutations in the sarcomeric protein myopalladin in patients with dilated cardiomyopathy

Meyer, Thomas; Ruppert, Volker; Ackermann, Sarah; Richter, Anette; Perrot, Andreas; Sperling, Silke R; Posch, Maximilian G; Maisch, Bernhard; Pankuweit, Sabine
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
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Recently, missense mutations in titin-associated proteins have been linked to the pathogenesis of dilated cardiomyopathy (DCM). The objective of this study was to search for novel disease-associated mutations in the two human titin-binding proteins myopalladin and its amino-terminal-interacting partner cardiac ankyrin-repeat protein (CARP). In a cohort of 255 cases with familial and sporadic DCM, we analyzed the coding regions and all corresponding intron flanks located in the MYPN and CARP-encoding ANKRD1 gene. Two heterozygous missense mutations were detected in the MYPN gene (p.R955W and p.P961L), but neither of these mutations was found in 300 healthy controls. Both mutations were located in the α-actinin-binding region of myopalladin. Endomyocardial biopsies from the p.R955W carrier showed normal subcellular localization of myopalladin and α-actinin in cardiac myocytes, while their regular sarcomeric staining pattern was significantly disrupted in the p.P961L carrier, indicating that disturbed myofibrillogenesis and altered sarcomere assembly are the cause of the disease. In the ANKRD1 gene, we identified synonymous base exchanges (c.108T>C and c.-79C>T, respectively), but no non-synonymous mutations. In summary, we have identified novel missense mutations in the third immunoglobulin-like domain of myopalladin...

‣ Structural and Functional Impact of Cancer Related Missense Somatic Mutations

Shi, Zhen; Moult, John
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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A number of large scale cancer somatic genome sequencing projects are now identifying genetic alterations in cancers. Evaluation of the effects of these mutations is essential for understanding their contribution to tumorigenesis. We have used SNPs3D, a software suite originally developed for analyzing non-synonymous germ line variants, to identify single base mutations with a high impact on protein structure and function. Two machine learning methods are used, one identifying mutations that destabilize protein three dimensional structure, and the other utilizing sequence conservation, and detecting all types of effects on in vivo protein function. Incorporation of detailed structure information into the analysis allows detailed interpretation of the functional effects of mutations in specific cases. Data from a set of breast and colorectal tumors were analyzed. In known cancer genes, approaching 100% of mutations are found to impact protein function, supporting the view that these methods are appropriate for identifying driver mutations. Overall, 50% to 60% of all somatic missense mutations are predicted to have a high impact on structural stability or to more generally affect the function of the corresponding proteins. This value is similar to the fraction of all possible missense mutations that have high impact...

‣ Molecular and structural characterization of five novel mutations in the Bruton's tyrosine kinase gene from patients with X-linked agammaglobulinemia.

Saha, B. K.; Curtis, S. K.; Vogler, L. B.; Vihinen, M.
Fonte: The Feinstein Institute for Medical Research Publicador: The Feinstein Institute for Medical Research
Tipo: Artigo de Revista Científica
Publicado em /07/1997 Português
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BACKGROUND: The Btk (Bruton's tyrosine kinase) gene has been shown to be mutated in the human immunodeficiency disease, XLA (X-linked agammaglobulinemia). Btk is a member of the Tec family of cytosolic protein tyrosine kinases with distinct functional domains PH, TH, SH3, SH2, and kinase. Mutations have been observed in each of the Btk subdomains in XLA. We have analyzed the Btk gene in six XLA patients from five unrelated families. MATERIALS AND METHODS: DNA was prepared from the patients peripheral blood. The Btk exons including the junctional sequences were analyzed by single-strand conformation polymorphism (SSCP) followed by direct nucleotide sequencing after PCR-amplification. For structural analysis, the missense mutations were introduced into three-dimensional models of the PH and kinase domains of Btk and the outcome was predicted based on the knowledge of the protein function. RESULTS: Five novel mutations and two novel polymorphisms, all of which resulted from single-base alterations, were identified. Three of the five mutations were in the PH domain and two were in the kinase domain of Btk. Three of these mutations were of the missense type, two of which altered the same codon in the PH domain; the third one was located in the kinase domain. The fourth mutation was a point deletion in the PH domain causing a frameshift followed by premature termination. The fifth mutation was a splice donor-site mutation within the kinase domain which could result in an exon skipping. In four of the five instances...

‣ Spectrum of mutations in the Batten disease gene, CLN3.

Munroe, P B; Mitchison, H M; O'Rawe, A M; Anderson, J W; Boustany, R M; Lerner, T J; Taschner, P E; de Vos, N; Breuning, M H; Gardiner, R M; Mole, S E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1997 Português
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Batten disease (juvenile-onset neuronal ceroid lipofuscinosis [JNCL]) is an autosomal recessive condition characterized by accumulation of lipopigments (lipofuscin and ceroid) in neurons and other cell types. The Batten disease gene, CLN3, was recently isolated, and four disease-causing mutations were identified, including a 1.02-kb deletion that is present in the majority of patients (The International Batten Disease Consortium 1995). One hundred eighty-eight unrelated patients with JNCL were screened in this study to determine how many disease chromosomes carried the 1.02-kb deletion and how many carried other mutations in CLN3. One hundred thirty-nine patients (74%) were found to have the 1.02-kb deletion on both chromosomes, whereas 49 patients (41 heterozygous for the 1.02-kb deletion) had mutations other than the 1.02-kb deletion. SSCP analysis and direct sequencing were used to screen for new mutations in these individuals. Nineteen novel mutations were found: six missense mutations, five nonsense mutations, three small deletions, three small insertions, one intronic mutation, and one splice-site mutation. This report brings the total number of disease-associated mutations in CLN3 to 23. All patients homozygous for mutations predicted to give rise to truncated proteins were found to have classical JNCL. However...

‣ Intragenic telSMN mutations: frequency, distribution, evidence of a founder effect, and modification of the spinal muscular atrophy phenotype by cenSMN copy number.

Parsons, D W; McAndrew, P E; Iannaccone, S T; Mendell, J R; Burghes, A H; Prior, T W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1998 Português
Relevância na Pesquisa
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The autosomal recessive neuromuscular disorder proximal spinal muscular atrophy (SMA) is caused by the loss or mutation of the survival motor neuron (SMN) gene, which exists in two nearly identical copies, telomeric SMN (telSMN) and centromeric SMN (cenSMN). Exon 7 of the telSMN gene is homozygously absent in approximately 95% of SMA patients, whereas loss of cenSMN does not cause SMA. We searched for other telSMN mutations among 23 SMA compound heterozygotes, using heteroduplex analysis. We identified telSMN mutations in 11 of these unrelated SMA-like individuals who carry a single copy of telSMN: these include two frameshift mutations (800ins11 and 542delGT) and three missense mutations (A2G, S262I, and T274I). The telSMN mutations identified to date cluster at the 3' end, in a region containing sites for SMN oligomerization and binding of Sm proteins. Interestingly, the novel A2G missense mutation occurs outside this conserved carboxy-terminal domain, closely upstream of an SIP1 (SMN-interacting protein 1) binding site. In three patients, the A2G mutation was found to be on the same allele as a rare polymorphism in the 5' UTR, providing evidence for a founder chromosome; Ag1-CA marker data also support evidence of an ancestral origin for the 800ins11 and 542delGT mutations. We note that telSMN missense mutations are associated with milder disease in our patients and that the severe type I SMA phenotype caused by frameshift mutations can be ameliorated by an increase in cenSMN gene copy number.