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Results for “mutation analysis”

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At least 1,081 records · Page 60Linked to original sources
PubMed2004

Mutation analysis of the BRAF codon 599 in malignant pleural mesothelioma by enriched PCR-RFLP.

BRAF encodes a RAS-regulated serine/threonine kinase that mediates the pathway for cell growth and malignant transformation. Point mutations of BRAF were reported recently in 66% of melanomas, over 30% of thyroid papillary and low-grade ovarian cancers, and a smaller percentage of other human cancers. Mutations in malignant cells were reported to occur only in exons 11 and 15. Among these mutations, BRAF V599E is most frequent and proved to invert its transcript to the dominant active form. To exclude the interference of co-existing normal cells in clinical samples, we developed a new enriched PCR-RFLP assay for detecting mutations of BRAF codon 599 mutation. The sensitivity of this assay was examined to find that one mutant allele among 10(2) wild-type alleles could be detected. We applied this method for 53 cases of primary malignant pleural mesotheliomas (MPMs) and 6 cell lines and found no mutations in these samples. Our results demonstrate that the developed enriched PCR-RFLP is a sensitive assay to detect BRAF codon 599 mutation. However, it may be a rare type of mutation in MPMs. Our new assay is useful and can be applied for screening of BRAF codon 599 mutation in various kinds of clinical samples.

Cell Division↗
PubMed1995

Expression and mutation analysis of the p53 gene in uterine papillary serous carcinoma.

BACKGROUND: The status of p53 protein expression was determined by immunohistochemistry and correlated with genetic analysis and clinical outcome in patients with uterine papillary serous carcinoma (UPSC). METHODS: Twenty-two patients with UPSC were identified and immunohistochemical staining of p53 protein was performed. Staining was analyzed by quantitating nuclear reactivity in 500 randomly counted cells per specimen. DNA analysis was performed on the tumors using single-strand conformation polymorphism (SSCP) analysis of exons 4-10 of the p53 gene, followed by DNA sequencing of all variants. Clinical data and patient status were ascertained from chart reviews. RESULTS: Sixteen of the 22 (73%) tumors were scored as p53-overexpressing as determined by immunohistochemical analysis. Patients whose tumors overexpressed p53 had a statistically significant shorter survival than those whose tumors did not (P < 0.022). DNA analysis of the 22 tumors revealed five with mutations of the p53 gene. Only three of these mutations were observed in tumors that overexpressed p53. CONCLUSIONS: A relatively large percentage of UPSC tumors exhibited high p53 immunoreactivity. Overexpression is correlated with poor prognosis. Positive immunohistochemistry for p53 protein in UPSC is not necessarily indicative of a genetic mutation.

Aged↗
PubMed2001

Mutation analysis of the methyl-CpG-binding protein 2 gene (MECP2) in Rett patients with preserved speech.

Genomic DNAs from 35 Japanese sporadic patients with Rett syndrome (RTT) were screened for DNA mutations in the entire coding region and exon-intron boundaries of methyl-CpG-binding protein 2 (MECP2). We detected mutations in 30 (85.7%) of 35 patients. Among these 35 RTT patients, five patients (14%) had the preserved speech variant of this disease. Four respective mutations (R133C, R306C, R294X, 2 base pair (bp) deletion) were found in these five patients. Two patients had the same missense mutation, R133C. The patients with the R133C mutation and one with frameshift mutation presented the relatively mild clinical presentation, and the R133C mutation was not found in any other patient without preserved speech. We confirmed that the preserved speech variant is one of the clinical phenotypes of RTT and is also caused by MECP2 mutation. We speculated that the clinical phenotype of patients with the R133C missense mutation might be mild.

Adult↗
PubMed2000

Mutational analysis of GLUT1 (SLC2A1) in Glut-1 deficiency syndrome.

Fifteen children presenting with infantile seizures, acquired microcephaly, and developmental delay were found to have novel heterozygous mutations in the GLUT1 (SLC2A1). We refer to this condition as the Glut-1 Deficiency Syndrome (Glut-1 DS). The encoded protein (Glut-1), which has 12 transmembrane domains, is the major glucose transporter in the mammalian blood-brain barrier. The presence of GLUT1 mutations correlates with reduced cerebrospinal fluid glucose concentrations (hypoglycorrhachia) and reduced erythrocyte glucose transporter activities in the patients. We used Florescence in situ hybridization, PCR, single-stranded DNA conformational polymorphism, and DNA sequencing to identify novel GLUT1 mutations in 15 patients. These abnormalities include one large-scale deletion (hemizygosity), five missense mutations (S66F, R126L, E146K, K256V, R333W), three deletions (266delC, 267A>T; 904delA; 1086delG), three insertions (368-369 insTCCTGCCCACCACGCTCACCACG, 741-742insC, 888-889insG), three splice site mutations (197+1G>A; 1151+1G>T; 857T>G, 858G>A, 858+1del10), and one nonsense mutation (R330X). In addition, six silent mutations were identified in exons 2, 4, 5, 9, and 10. The K256V missense mutation involved the maternally derived allele in the patient and one allele in his mother. A spontaneous R126L missense mutation also was present in the paternally derived allele of the patient. The apparent pathogenicity of these mutations is discussed in relation to the functional domains of Glut-1.

Alternative Splicing↗
PubMed2000

Mutational analysis of tumor suppressor gene p53 in feline vaccine site-associated sarcomas.

OBJECTIVES: To investigate the role of tumor suppressor gene p53 mutation in feline vaccine site-associated sarcoma (VSS) development and to evaluate the relationship between p53 nucleotide sequence and protein expression. SAMPLE POPULATION: Formalin-fixed paraffin-embedded tissues of 8 feline VSS with dark p53 immunostaining (high p53 expression) and 13 feline VSS with faint or no staining (normal p53 expression). PROCEDURE: DNA was extracted from neoplastic and normal tissue from each paraffin block. The following 3 regions of the p53 gene were amplified by polymerase chain reaction: 379 base pair (bp) region of exon 5, intron 5, and exon 6, 108 bp region of exon 7, and 140 bp region of exon 8. Amplified p53 products were sequenced and compared with published feline p53. The p53 mutations identified were correlated with p53 mutations predicted by immunostaining. RESULTS: Neoplastic cells of 5 of 8 (62.5%) VSS that had high p53 expression harbored single missense mutations within the p53 gene regions examined. The p53 gene mutations were not detected in the 13 tumors with normal p53 immunostaining. Nonneoplastic tissues adjacent to all 21 VSS lacked mutations of these p53 gene regions. CONCLUSIONS: The p53 gene mutations were restricted to neoplastic tissue and, therefore, were unlikely to predispose to VSS. However, p53 mutations may have contributed to cancer progression in 5 of the 21 VSS. There was very good (kappa quotient = 0.67 with a confidence limit of 0.3 to 1.0), although not complete, agreement between prediction of mutation by p53 immunostaining and identification of mutations by sequencing of key p53 gene regions.

Animals↗
PubMed1999

Mutation analysis of the MEN1 gene in Belgian patients with multiple endocrine neoplasia type 1 and related diseases.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by tumors in parathyroids, enteropancreatic endocrine tissues, anterior pituitary, and other tissues. The gene for MEN1 has recently been cloned and shown to code for a 610-amino acid protein of enigmatic function which probably acts as a tumor suppressor. Several mutations causing the MEN1 phenotype have been recently identified. In order to determine the spectrum of MEN1 gene mutations in a sample of 25 Belgian patients, we have systematically screened the 10 exons and adjacent sequences of the MEN1 gene by means of an automatic sequencing protocol. Twelve different mutations were identified including nonsense, frameshift, splicing, and missense mutations. Two of these mutations (D172Y and 357del4) occurred more than once. A missense mutation was also found in a kindred with familial hyperparathyroidism. We observed no significant correlation between the nature or position of mutation and the clinical status. We have also detected 6 intragenic polymorphisms and DNA sequence variants and have analyzed their frequencies in our population.

Belgium↗
PubMed2000

Mutational analysis of X-linked adrenoleukodystrophy gene.

X-linked adrenoleukodystrophy (ALD) is an inherited peroxisomal disorder characterized by progressive neurological dysfunction, occasionally associated with adrenal insufficiency. The clinical phenotypes of ALD are quite variable, and include childhood ALD, adult-onset ALD, adrenomyeloneuropathy, and Addison's disease only. Although the causative gene for ALD has been identified, the physiological role of the gene product remains to be clarified. Despite many mutations having been identified in patients with these clinical phenotypes, the genotype-phenotype correlations have not been clarified. The authors investigated genotype-phenotype correlations in ALD by analyses on 29 unrelated Japanese patients with ALD and by a review of the literature. All the phenotypes were associated with mutations leading to protein truncation, as well as those resulting in subtle amino acid changes. Furthermore, there were no differences in phenotypic expression among the natures of the subtle amino acid changes. All these data indicate that no obvious correlations exist between the phenotypes of ALD patients and their genotypes, suggesting that other genetic or environmental factors may also be involved in determining phenotypic expression in ALD.

Adrenoleukodystrophy↗
PubMed1997

Mutation analysis provides additional proof that mottled is the mouse homologue of Menkes' disease.

Menkes' disease (MD) and occipital horn syndrome (OHS) are allelic X-linked disorders caused by mutations in the copper ion transporting ATPase, ATP7A. Genetic, phenotypic and biochemical data suggest that mottled mutants in the mouse, which range in severity and phenotype, are caused by mutations in Atp7a, the mouse homologue of ATP7A. As the only causal mutation in Atp7a has been reported in one very mild allele thought to be a model for OHS, Atp7aMo-blo (mottled blotchy), we sequenced the entire 4.5 kb coding region of three other mottled mutants, two of which are thought to be models for classical MD (AtpaMo-br, AtpaMo-13H) and one with a slightly milder phenotype (Atp7aMo-vbr). Although no causal mutation was found in Atp7aMo-13H, mutations which can be predicted to affect Atp7a function were identified in Atp7aMo-br and Atp7aMo-vbr. A 6 bp deletion of nucleotides 2478-2483, which can be predicted to affect the correct processing of the protein, was found in Atp7aMo-br and an A3189-->C nucleotide change, which results in lysine-->threonine amino acid substitution in the phosphorylation domain, was found in Atp7aMo-vbr. Thus we provide further proof that mottled mutants will provide excellent models for MD as well as OHS.

Adenosine Triphosphatases↗
PubMed1998

Mutational analysis of the tumor suppressor Smad2 in acute lymphoid and myeloid leukemia.

Smad4 is a tumor suppressor that is inactivated in about 50% of pancreatic carcinomas. Mutations in this gene have also been found with variable, yet much lower frequency in other tumor types and were absent from a large number of samples from patients with hematological malignancies. Smad2 shows considerable sequence similarity with Smad4 and cooperates with it in the growth inhibitory TGF-beta pathway. Smad2 mutations have been found in a fraction of colon carcinomas and have been shown to impair the function of the corresponding proteins. However, only a few other tumor types have been screened for Smad2 mutations so far. Therefore, we analyzed 50 primary tumor samples from patients with acute lymphoid or myeloid leukemia (ALL or AML) and five cell lines of hematopoietic origin for alterations in the Smad2 gene. None of the specimens tested carried mutations in the conserved MH1 or MH2 domains of Smad2.

Base Sequence↗
PubMed2000

Germline and somatic mutation analysis of MLH3 in MSI-positive colorectal cancer.

Microsatellite instability (MSI) is characteristic of hereditary nonpolyposis colorectal cancer, and occurs in a subset (10 to 15%) of unselected colorectal cancer cases. In hereditary nonpolyposis colorectal cancer, MSI is caused by defects in five mismatch repair genes, and in sporadic cases the main cause seems to be somatic MLH1 promoter methylation. Most likely additional hereditary nonpolyposis colorectal cancer genes remain to be discovered. Genes with simple repeats in their coding region are often targets for deletions in MSI-positive tumors. Several genes (TGFbeta RII, IGFIIR, MSH3, MSH6, BAX, MBD4) with significance in tumorigenesis harbor repeats in their coding regions and are often somatically inactivated because of deletions causing frameshifts. Recently, a novel human mismatch repair gene, MLH3, was cloned and shown to be involved in mammalian mismatch repair. To evaluate the possible role of MLH3 in hereditary cancer, we performed germline single-strand conformation polymorphism-analysis for 52 patients displaying features of inherited colorectal cancer. Forty-six of these had been diagnosed with MSI-positive tumors. No germline mutations were found. Similar to MSH3 and MSH6, MLH3 harbors mononucleotide repeats, ie, (A(6))-(A(9)), in its coding region, which makes it a putative target for somatic mutations in MSI-positive tumors. To evaluate its somatic inactivation we performed a deletion search focusing on eight exonic MLH3 mononucleotide repeats in a series of 93 MSI-positive tumors. Somatic deletions were found in 8.6% of the samples, a frequency similar to one detected in neutral noncoding mononucleotide repeats. No evidence of involvement of MLH3 in MSI tumorigenesis was obtained.

Amino Acid Substitution↗
PubMed2006

Mutational analysis of the glycosylphosphatidylinositol (GPI) anchor pathway demonstrates that GPI-anchored proteins are required for cell wall biogenesis and normal hyphal growth in Neurospora crassa.

Using mutational and proteomic approaches, we have demonstrated the importance of the glycosylphosphatidylinositol (GPI) anchor pathway for cell wall synthesis and integrity and for the overall morphology of the filamentous fungus Neurospora crassa. Mutants affected in the gpig-1, gpip-1, gpip-2, gpip-3, and gpit-1 genes, which encode components of the N. crassa GPI anchor biosynthetic pathway, have been characterized. GPI anchor mutants exhibit colonial morphologies, significantly reduced rates of growth, altered hyphal growth patterns, considerable cellular lysis, and an abnormal "cell-within-a-cell" phenotype. The mutants are deficient in the production of GPI-anchored proteins, verifying the requirement of each altered gene for the process of GPI-anchoring. The mutant cell walls are abnormally weak, contain reduced amounts of protein, and have an altered carbohydrate composition. The mutant cell walls lack a number of GPI-anchored proteins, putatively involved in cell wall biogenesis and remodeling. From these studies, we conclude that the GPI anchor pathway is critical for proper cell wall structure and function in N. crassa.

Blotting, Western↗
PubMed1992

Mutation analysis for prenatal diagnosis and heterozygote detection of Gaucher disease type III (Norrbottnian type).

A single base substitution in exon 10 of the glucocerebrosidase gene was detected in families affected by Gaucher disease (GD) type III. This mutation, which results in the substitution of proline for leucine in position 444 of glucocerebrosidase, has been shown to result in type III GD in a Swedish population. Three fetuses at risk for GD type III were diagnosed as homozygous for the mutation and the pregnancies were terminated. In a fourth pregnancy, one parent was excluded as being a carrier and the risk of having a child affected by GD was ignored. Direct analysis of common mutations causal to GD is now available and improves prenatal diagnosis in families where the molecular defect has been characterized.

Base Sequence↗
PubMed2004

Microarray-based mutation analysis of the ABCA4 (ABCR) gene in autosomal recessive cone-rod dystrophy and retinitis pigmentosa.

Mutations in the ABCA4 gene have been associated with autosomal recessive Stargardt disease (STGD1), cone-rod dystrophy (CRD), and retinitis pigmentosa (RP). We employed a recently developed genotyping microarray, the ABCR400-chip, to search for known ABCA4 mutations in patients with isolated or autosomal recessive CRD (54 cases) or RP (90 cases). We performed detailed ophthalmologic examinations and identified at least one ABCA4 mutation in 18 patients (33%) with CRD and in five patients (5.6%) with RP. Single-strand conformation polymorphism (SSCP) analysis and subsequent DNA sequencing revealed four novel missense mutations (R24C, E161K, P597S, G618E) and a novel 1-bp deletion (5888delG). Ophthalmoscopic abnormalities in CRD patients ranged from minor granular pigmentary changes in the posterior pole to widespread atrophy. In 12 patients with recordable electroretinogram (ERG) tracings, a cone-rod pattern was detected. Three patients demonstrated progression from a retinal dystrophy resembling STGD1 to a more widespread degeneration, and were subsequently diagnosed as CRD. In addition to a variable degree of atrophy, all RP patients displayed ophthalmologic characteristics of classic RP. When detectable, ERG recordings in these patients demonstrated rod-cone patterns of photoreceptor degeneration. In conclusion, in this study, we show that the ABCA4 mutation chip is an efficient first screening tool for arCRD.

ATP-Binding Cassette Transporters↗
PubMed2002

Mutational analysis of the Caenorhabditis elegans ankyrin gene unc-44 demonstrates that the large spliceoform is critical for neural development.

In Caenorhabditis elegans, unc-44 mutations affect axonal outgrowth and guidance, leading to locomotory defects. The wild-type unc-44 gene encodes a family of ankyrin proteins, which, in addition to the conventional ankyrins, includes a novel ankyrin isoform with an extended C-terminal domain, referred to AO13 ankyrin. Six spontaneous unc-44 mutations and their reversions were analyzed in order to localize regions critical for gene function. The q331::Tc1 and rh1013::Tc1 mutations were mapped to the portion of the gene encoding the conventional ankyrins, mn339 had an uncharacterized 2-kb insertion in the serine/threonine/glutamic acid/proline-rich (STEP) repeat block 5, st200::Tc5(variant) and rh1042::Tc1 were localized near the C-terminus, and mn259 resulted from two Tc1 insertions, one in STEP block 6 and the other near the C-terminus. Tc1 excisions in several revertants resulted either in the restoration of the wild-type sequence, or were associated with small in-frame deletions or insertions. Reversion of mn339 resulted in the net excision of 2463 bp of genomic DNA, including the region encoding parts of STEP blocks 5 and 6 and the intervening hydrophobic region. Interestingly, additional Tc1 insertions at a 5' exon/intron boundary were found in revertants of st200 and rh1042. Reversion of the st200::Tc5 mutation resulted in excision of the Tc5 element, and the insertion of two copies of Tc1 at different sites. The wild-type unc-44 gene produces multiple transcripts - shorter RNAs determined to be approximately 1, 3.2, 5, 6, and 7 kb long, and two large transcripts estimated to be 22 and 26 kb in length. The largest transcripts were affected by all unc-44 mutations and are proposed to be essential for axonal outgrowth and guidance.

Alternative Splicing↗
PubMed1999

Mutation analysis of hBUB1 in aneuploid HNSCC and lung cancer cell lines.

Aneuploidy is frequently observed in many types of human cancer cells, suggesting that mutations of genes required for chromosomal stability may occur in human tumors. The BUB gene is a component of the mitotic checkpoint in budding yeast that delays anaphase in the presence of spindle damage thus increasing the probability of successful delivery of a euploid genome to each daughter cell. Recently, human homologues of the BUB gene were identified and mutant alleles of hBUB1 were detected in two colorectal tumor cell lines. Transfection of one mutant allele led to dominant disruption of the mitotic checkpoint control in a euploid cell, suggesting that aneuploidy in some tumors could be due to defects in the mitotic checkpoint. We analyzed the entire coding sequence of hBUB1 for mutation in 31 head and neck squamous cell carcinoma (HNSCC) and lung cancer cell lines, most with severe aneuploidy. We found expression of the hBUB1 gene in all cell lines and only a single nucleotide substitution in one cell line without a resultant change in amino acid sequence. Our study demonstrates that hBUB1 is rarely a target for genetic alterations in tumors of the respiratory tract.

Aneuploidy↗