Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “mutation analysis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources
PubMed1997

Mutational analysis of the SOX9 gene in campomelic dysplasia and autosomal sex reversal: lack of genotype/phenotype correlations.

It has previously been shown that, in the heterozygous state, mutations in the SOX9 gene cause campomelic dysplasia (CD) and the often associated autosomal XY sex reversal. In 12 CD patients, 10 novel mutations and one recurrent mutation were characterized in one SOX9 allele each, and in one case, no mutation was found. Four missense mutations are all located within the high mobility group (HMG) domain. They either reduce or abolish the DNA-binding ability of the mutant SOX9 proteins. Among the five nonsense and three frameshift mutations identified, two leave the C-terminal transactivation (TA) domain encompassing residues 402-509 of SOX9 partly or almost completely intact. When tested in cell transfection experiments, the recurrent nonsense mutation Y440X, found in two patients who survived for four and more than 9 years, respectively, exhibits some residual transactivation ability. In contrast, a frameshift mutation extending the protein by 70 residues at codon 507, found in a patient who died shortly after birth, showed no transactivation. This is apparently due to instability of the mutant SOX9 protein as demonstrated by Western blotting. Amino acid substitutions and nonsense mutations are found in patients with and without XY sex reversal, indicating that sex reversal in CD is subject to variable penetrance. Finally, none of 18 female patients with XY gonadal dysgenesis (Swyer syndrome) showed an altered SOX9 banding pattern in SSCP assays, providing evidence that SOX9 mutations do not usually result in XY sex reversal without skeletal malformations.

Child↗
PubMed2006

Gene mutation analysis and immunohistochemical study of beta-catenin in odontogenic tumors.

In the present study the significance of nuclear/cytoplasmic expression of beta-catenin (CTNNB1) and mutation of the CTNNB1 gene (CTNNB1) in odontogenic tumors was examined. Six ameloblastomas (five follicular ameloblastomas and one plexiform ameloblastoma) and three malignant odontogenic tumors (one metastasizing ameloblastoma, one ameloblastic carcinoma, and one primary intraosseous odontogenic carcinoma) were investigated for CTNNB1 expression and CTNNB1 mutation. Immunohistochemically, all follicular ameloblastomas and one primary intraosseous odontogenic carcinoma exhibited focal and moderate nuclear/cytoplasmic expression of CTNNB1, whereas the plexiform ameloblastoma and the remaining two malignant odontogenic tumors had entirely membranous expression. CTNNB1 mutation at codon 40 of exon 3 was found in one of the six follicular ameloblastomas. The other five follicular ameloblastomas, the plexiform ameloblastoma, and the three malignant odontogenic tumors did not show mutation in exon 3 of CTNNB1. These findings further confirmed that CTNNB1 mutation is not frequent in ameloblastoma and malignant odontogenic tumors, although the abnormality of Wnt signaling may be associated with some of these tumors.

Adolescent↗
PubMedDate not supplied

Mutation analysis of the TGFBI gene in Vietnamese with granular and Avellino corneal dystrophy.

PURPOSE: Mutations of the human transforming growth factor beta-induced gene (TGFBI) were reported to cause granular (GCD) and Avellino (ACD) corneal dystrophy in various nationalities. In this study we examined the TGFBI gene in a Vietnamese population with GCD and ACD. METHODS: Eight unrelated Vietnamese families, including 20 affected and 24 unaffected individuals, were examined; 50 normal Vietnamese individuals were used as controls. Genomic DNA was extracted from peripheral blood leukocytes. The TGFBI gene was analyzed using the polymerase chain reaction and direct sequencing. The corneal button was studied. RESULTS: Slit-lamp examination revealed typical features of GCD in most cases. A few features of ACD and a patient with an atypical form of GCD were also seen. Histopathological analysis of a GCD cornea showed deposits that stained bright red with Masson trichrome. Sequencing revealed three distinct mutations: R555W in six families, R124H in one family, and D123H in another. CONCLUSIONS: R555W and R124H mutations were co-segregated with the disease phenotype and thus caused GCD and ACD, respectively, in the families studied. The R555W detected in six of the eight families indicates that the GCD phenotype may be the most common in Vietnamese individuals, unlike in other Asians (Japanese and Korean), where ACD is most common (>90%). The D123H mutation may cause an atypical variant of GCD.

Adolescent↗
PubMedDate not supplied

Mutational analysis of p53 in 16 cases of acute lymphoblastic leukemia and Burkitt's lymphoma.

BACKGROUND AND OBJECTIVE: Improvements in therapy for patients with B-cell acute lymphoblastic leukemia (ALL) and Burkitt's lymphoma (BL) depend on the identification of subsets of patients who require more intensive therapy. Abnormalities of the p53 gene are the most common molecular lesions in human cancer, and may be of prognostic significance in hematologic malignancies. In this study, we examined the p53 gene status in a group of patients with ALL/BL to determine whether some types of mutants were more frequent in this selected group of patients. METHODS: We selected a group of 16 patients with acute lymphoblastic leukemia (ALL) and Burkitt's lymphoma (BL) in order to investigate the presence of p53 mutations. DNA obtained from affected organs (bone marrow, lymph node and a renal mass) was used for the molecular studies. Single-strand conformation polymorphism (SSCP) analysis of exons 5 to 9 of the gene was used to detect p53 mutants. After detecting an abnormal migration pattern on the SSCP, mutations were determined by direct sequencing. RESULTS: Point mutations were found in eight patients; a misense mutation in seven cases and a non-sense mutation in one case. The normal allele was also identified in 7 mutated samples. The same mutation at codon 282 was identified in three different patients, in whom an identical conformer was detected after SSCP analysis. Mutation at codon 282 was present in an extramedular relapse (renal) appearing after a BMT. No such alteration was present in the bone marrow analyzed at the same time. INTERPRETATION AND CONCLUSIONS: Our findings suggest that p53 mutations are quite frequent in recognized clinical groups. The criteria chosen in this study allowed us to identify a high percentage of the samples with mutation. Different malignant phenotypes could be determined by functional heterogeneity of p53 mutants.

Adolescent↗
PubMed1998

Mutation analysis of UBE3A in Angelman syndrome patients.

Angelman syndrome (AS) is caused by chromosome 15q11-q13 deletions of maternal origin, by paternal uniparental disomy (UPD) 15, by imprinting defects, and by mutations in the UBE3A gene. UBE3A encodes a ubiquitin-protein ligase and shows brain-specific imprinting. Here we describe UBE3A coding-region mutations detected by SSCP analysis in 13 AS individuals or families. Two identical de novo 5-bp duplications in exon 16 were found. Among the other 11 unique mutations, 8 were small deletions or insertions predicted to cause frameshifts, 1 was a mutation to a stop codon, 1 was a missense mutation, and 1 was predicted to cause insertion of an isoleucine in the hect domain of the UBE3A protein, which functions in E2 binding and ubiquitin transfer. Eight of the cases were familial, and five were sporadic. In two familial cases and one sporadic case, mosaicism for UBE3A mutations was detected: in the mother of three AS sons, in the maternal grandfather of two AS first cousins, and in the mother of an AS daughter. The frequencies with which we detected mutations were 5 (14%) of 35 in sporadic cases and 8 (80%) of 10 in familial cases.

Angelman Syndrome↗
PubMed1999

Mutation analysis of the putative tumor suppression gene PTEN/MMAC1 in sporadic breast cancer.

PTEN/MMAC1, a potential human tumor suppressor gene, has been found to have inactivating mutations in several types of cancer, including breast cancer. The incidence of breast cancer in Chinese is quite low in comparison with Caucasians, and genetic factors may play some roles. To further determine the role of PTEN/MMAC1 in breast cancer in Chinese, we used loss of heterozygosity (LOH), single strand conformation polymorphism (SSCP) with direct sequencing of variant bands, and Southern blot analysis methods to analyze mutations in PTEN/MMAC1 in 52 cases of breast cancer. None had LOH at chromosome 10q23.3. One mutation was identified, a somatic 3-base deletion, in one case. Our results suggest PTEN/MMAC1 does not play a major role in the development of sporadic breast cancer.

Adult↗
PubMed1998

Transferrin receptor mutation analysis in hereditary hemochromatosis patients.

The Cys282-->Tyr mutation in the HFE gene is carried by the majority of hereditary hemochromatosis patient chromosomes, yet some patients do not seem to harbor any mutation in this gene. This suggests a possibility that these patients may have a mutation in other genes in the same pathway as HFE. We analyzed the cDNA sequences of transferrin receptor (TFR), which was recently shown to interact with HFE, in twenty-one hereditary hemochromatosis patients including sixteen individuals who did not carry a Cys282-->Tyr mutation. A nucleotide substitution (424A-->G), which resulted in the Ser142-->Gly amino acid substitution, was the only amino acid polymorphism detected in the open reading frame of the TFR gene in these patients. This amino acid substitution was a rather common polymorphism in the general population (49%) and its frequency did not significantly differ in the hereditary hemochromatosis (HH) patients regardless of the HFE genotype. Thus, amino acid changes in the TFR gene do not appear to play a role in HH even when the patients do not have a HFE mutation. However, this study does not rule out the possibility of the involvement of mutations in non-coding regions.

Amino Acid Substitution↗
PubMed1978

Mutational analysis of the operators of bacteriophage lambda.

Oc mutations in the operators of bacteriophage lambda have been used to analyze the functional organization of the operators. In each operator, repressor binding sites 1 and 2, as identified biochemically, were found to be primarily responsible for the repressor affinity of the operators in vitro and for the repression of lytic functions in vivo. In addition, both sites were shown to be involved in the action of cro product at the operators. The data obtained have been used to estimate the repressor affinities of the individual binding sites. These affinities suggest that repressor bound at OR1 and OR2 interacts cooperatively. The results obtained support a model for repression of the early lambda operons where repressor bound at binding sites 1 and 2 interferes with RNA polymerase binding to the promotor sites.

Base Sequence↗
PubMed2002

Mutational analysis of Plasmodium falciparum dihydrofolate reductase: the role of aspartate 54 and phenylalanine 223 on catalytic activity and antifolate binding.

The catalytic activity and ability to confer resistance to antifolates of Plasmodium falciparum dihydrofolate reductase (pfDHFR) through single and double mutations at Asp-54 and Phe-223 were investigated. A single Asp54Glu (D54E) mutation in the pfDHFR domain greatly decreased the catalytic activity of the enzyme and affected both the K(m) values for the substrate dihydrofolate and the K(i) values for pyrimethamine, cycloguanil and WR99210. The Phe223Ser (F223S) single mutant had unperturbed kinetics but had very poor affinity with the first two antifolates. The ability to confer high resistance to the antifolates of F223S enzyme was, however, abolished in the D54E+F223S double mutant enzyme. When D54E mutation was present together with the A16V+S108T double mutation, the effects on the K(m) values for the substrate dihydrofolate and the binding affinity of antifolates were much more pronounced. The severely impaired kinetics and poor activity observed in A16V+S108T+D54E enzyme could, however, be restored when F223S was introduced, while the binding affinities to the antifolates remained poor. The experimental findings can be explained with a model for substrate and inhibitor binding. Our data not only indicate the importance of Asp-54 of pfDHFR in catalysis and inhibitor binding, but also provide evidence that infer the potentially crucial function of the C-terminal portion of pfDHFR domain.

Animals↗
PubMed1997

Mutation analysis of the BRCA2 gene in breast/ovarian cancer Spanish families: identification of two new mutations.

The recently isolated gene BRCA2 is responsible for about 45% of familial breast cancer and the majority of male breast cancer families. We have screened 12 high risk breast/ovarian Spanish families for mutations in BRCA2, using SSCP followed by direct sequencing. We have found mutations in four of our 12 families (33.3%), including two with male breast cancer. Three of the mutations were frameshift and one was a missense. Two of the mutations have been previously published and two are new mutations.

Adult↗
PubMed1993

Mutational analysis of a ribonuclease III processing signal.

A mutational approach was employed to identify sequence and structural elements in a ribonuclease III processing signal that are important for in vitro enzymatic cleavage reactivity and selectivity. The substrate analyzed was the bacteriophage T7 R1.1 processing signal, a 60 nucleotide irregular RNA hairpin exhibiting an upper and lower dsRNA stem, separated by an asymmetric internal loop which contains the scissile phosphodiester bond. Altering the length of either the upper or lower dsRNA segment in R1.1 RNA dose not change the site of RNase III cleavage. However, decreasing the size of either the upper or lower dsRNA segment causes a progressive inhibition of processing reactivity. Omitting monovalent salt from the reaction buffer promotes cleavage of otherwise unreactive R1.1 deletion mutants. Accurate processing is maintained with R1.1 variants containing specific point mutations, designed to disrupt Watson-Crick (WC) base-pairing in a conserved sequence element within the upper dsRNA stem. The internal loop is not required for processing reactivity, as RNase III can accurately and efficiently cleave R1.1 variants in which this structure is WC base-paired. Moreover, an additional cleavage site is utilized in these variants, which occurs opposite the canonical site, and is offset by two nucleotides. The fully base-paired R1.1 variants form a stable complex with RNase III in Mg(2+)-free buffer, which can be detected by a gel electrophoretic mobility shift assay. In contrast, the complex of wild-type R1.1 RNA with RNase III is unstable during nondenaturing gel electrophoresis. Thus, a functional role of the T7 R1.1 internal loop is to enforce single enzymatic cleavage, which occurs at the expense of RNase III binding affinity.

Bacteriophage T7↗
PubMed2005

Mutational analysis of the yeast multidrug resistance ABC transporter Pdr5p with altered drug specificity.

Multidrug resistance ABC transporter Pdr5p of Saccharomyces cerevisiae is particularly important due to its ability to export a wide range of unrelated substrates. To clarify its function, we generated Pdr5p mutants by random mutagenesis and screened for mutants with altered drug specificity in vivo by using 5 drug compounds. Nine point mutations that caused significant changes in drug specificity distributed throughout the length of Pdr5p, namely, in the extracellular, transmembrane or cytoplasmic regions of the transporter. We then investigated their effects upon drug resistance, using 36 chemically related or distinct substrates. From this study, overall geometry of the Pdr5p was suggested to contribute in acquiring the enormous range of drug specificity. Based on their ability to inhibit the growth of the mutant strains, the 36 tested drugs were classified into: drugs to which the mutants responded differently (Group 1), drugs to which all the mutants showed sensitivity (Group 2), and drugs to which all the mutants exhibited resistance (Group 3). The ability of the compounds to be partitioned to the plasma membrane seemed an important factor for recognition by Pdr5p.

ATP-Binding Cassette Transporters↗
PubMedDate not supplied

[Mucopolysaccharidosis II (Hunter syndrome): identification of the carrier state of the disease by means of mutation analysis].

Identification of iduronate-2-sulfatase (IDS) gene mutations in patients with mucopolysaccharidosis type II (MPS II, Hunter syndrome) allows fast and reliable carrier detection in females, relatives of the patients. We describe here a study on a Hunter family where, after the identification of the primary genetic defect in the patients, we identified carriers unambiguously among at-risk female relatives and excluded such status in other subjects. This is an example of direct, DNA based diagnosis.

Carrier State↗
PubMed1994

Alternative splicing of the NF2 gene and its mutation analysis of breast and colorectal cancers.

To investigate a potential role of NF2, the gene responsible for hereditary bilateral acoustic neurinomas, during carcinogenesis of non-neurogenic tissues, we screened somatic mutations of NF2 in 55 breast cancers and 44 colorectal carcinomas by an RNase protection assay coupled with the reverse-transcriptase polymerase chain reaction (RT-PCR). By screening the entire coding region of the gene in these tumors, we detected missense mutations in the exon encoding the alpha-helical domain of the NF2 product in two colorectal carcinomas. No mutations were detected in any of the breast cancers. Our results suggested that inactivation of the NF2 gene was associated with carcinogenesis in some, but not the majority of, colorectal tumors. In the course of these analyses, we found various alternatively-spliced forms of NF2 transcript. These variants showed no specificity among the tissues examined except for one that resulted from alternative splicing at the 3'-region; this form was more abundantly expressed in skeletal and cardiac muscles than in other tissues.

Amino Acid Sequence↗
PubMed2003

Mutation analysis of the parkin gene in Russian families with autosomal recessive juvenile parkinsonism.

Autosomal recessive juvenile parkinsonism (AR-JP) is a form of hereditary parkinsonism characterized by variable clinical presentations and caused by mutations in a novel gene, parkin, on chromosome 6q25.2-27. Until now, no Russian cases of parkin-associated AR-JP have been reported on. We recruited 16 patients from 11 Russian families with dopa-responsive movement disorders according to the following criteria: 1) family history compatible with autosomal recessive inheritance; 2) onset of symptoms at </=30 years of age; and 3) the lack of mutations in the GTP cyclohydrolase I gene (in sporadic cases). Mutation screening of the parkin gene was carried out by a semiquantitative PCR assay and direct sequencing of the coding region. Six different parkin mutations (both deletions and point mutations) were identified in the index cases from four families, including a novel point mutation in the donor splice site (IVS1+1G-->A). The majority of our parkin-associated cases were characterized by early-onset dopa-responsive parkinsonism with benign course and slow progression (5 patients from two families have been followed for as long as 18-36 years), and 1 patient had a phenotype of dopa-responsive dystonia. This first description of Russian patients with AR-JP and molecularly proven parkin mutations confirms the widespread occurrence of this polymorphic hereditary extrapyramidal disorder.

Adult↗