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Results for “mutational screening”

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At least 343 records · Page 19Linked to original sources
PubMed2000

Severe cognitive impairment in DMD: obvious clinical indication for Dp71 isoform point mutation screening.

Duchenne muscular dystrophy is associated with variable degrees of selective cognitive defect with lower scores for verbal intelligence and reading abilities. A number of findings have shown that rearrangements located in the second part of the gene seem to be preferentially associated with cognitive impairment. Several dystrophin transcripts are expressed in the brain. The more distal of them, Dp71, is predominant. We have carried out a mutational analysis of Dp71 transcript in 12 DMD patients severely, mildly or not retarded, all without detectable deletion or duplication. We have detected five point mutations causing Dp71 premature translation termination. All were found among the more severely mentally retarded patients of this group (VIQ < 50 and/or no reading acquisition).

Adolescent↗
PubMed2000

Expression analysis and mutational screening of the epithelium-specific ets gene-1 (ESE-1) in patients with squamous anal cancer.

To investigate whether ESE-1 gene abnormalities are involved in alterations of epithelial cell differentiation in squamous anal cancer ESE-1 expression and structure were screened in six patients by reverse transcriptase-polymerase chain reaction (RT-PCR) and automated sequence analysis. The complete cDNA of isoform ESE-1b was always expressed and correctly spliced, with single nucleotide polymorphism being observed in two cases. Presence of ESE-1b point mutations was excluded. Expression of SPRR2A and ENDOA/CK8, two epithelium-specific ESE-1 target genes, were revealed by RT-PCR in all cases. This first report of expression of ESE-1, and of SPRR2A and ENDOA/CK8 (both related to terminal differentiation in different types of epithelia lining) in anal cancer excludes the hypothesis that these genes influenced carcinogenesis in our patients. Despite selecting of patients without clinical evidence of HPV infection, PCR consistently revealed HPV-16 DNA, highlighting the importance of HPV infection in anal cancer.

Adult↗
PubMed2002

Linkage analyses and SCN5A mutations screening in five sudden unexplained death syndrome (Lai-tai) families.

Sudden Unexplained Death Syndrome (SUDS) (or in Thai Lai-tai) share the same ECG pattern as Brugada Syndrome: RSR' and ST segment elevation in V1 to V3. Brugada Syndrome is a genetic disorder with the inheritance pattern of autosomal dominant (using the ECG pattern and unexplained sudden death as phenotype) and the cardiac sodium channel gene (SCN5A) mutations caused this syndrome. To determine whether SUDS was associated with the same mutations as Brugada Syndrome, the authors performed a linkage studies on 5 SUDS families with the Brugada Syndrome ECG pattern and found one family could not be excluded from linkage to SCN5A. However, the direct sequencing in 8 reported mutations on exon 5, 12, 17, 18 and 28 in this family failed to demonstrate the mutations. It was concluded that SUDS mutations maybe a novel mutation different from previously reported mutations, further genetic studies in SCN5A and other candidate genes might elucidate the molecular basis of SUDS.

Autopsy↗
PubMed2006

FOXE1 gene mutation screening by multiplex PCR/DHPLC in CHARGE syndrome and syndromic and non-syndromic cleft palate.

Denaturing high-performance liquid chromatography (DHPLC) has established itself as one of the most powerful tools for DNA variation screening. FOXE1, a highly GC-rich gene involved in syndromic cleft palate, is under investigation in thyroid dysgenesis, nonsyndromic cleft palate and squamous cell carcinoma. A technique for fast and simultaneous detection of sequence variants in the entire coding region of the FOXEl gene based on multiplex PCR/DHPLC is presented here. Given its characteristics of high sensitivity and rapidity, the testing strategy developed by us appears to be a reliable approach for FOXE1 analysis in the screening of a large population at risk.

Base Sequence↗
PubMed2003

Mutation screening of the C1 inhibitor gene among Hungarian patients with hereditary angioedema.

Hereditary angioneurotic edema (HAE) is an autosomal dominant disorder characterized by episodic local subcutaneous and submucosal edema caused by the deficiency of activated C1 esterase inhibitor protein (C1-INH, type I (C1NH): reduced serum antigen level, type II: reduced activity and normal serum antigen level). The aim of the present study was to determine the disease-causing mutations in the C1INH gene (SERPING1) among Hungarian HAE-patients. The estimated number of affected HAE-families in Hungary is 40-50, out of which 26 families (type I:23, type II:3) managed in a single center were enrolled in the current study. To detect large deletions/insertions, we used Southern-blotting analysis followed by real time PCR based gene dosage analysis. In the absence of large structural changes, we employed direct sequencing covering the whole coding region and splicing sites of the C1INH gene. Large deletions were detected in 4/23 (17.4%) type I families. We found the g.16788C>T (p.Arg444Cys) mutation in each 3, type II HAE-families. In the remaining type I families, 13 previously unreported mutations (g.638G>A, g.2238C>T, g.2534_2535delCT, g.2579_2620del42, g.2533G>A, g.2695G>A, g.2696_2697insT, g.4467C>T, g.14224A>T, g.14107delA, g.16749_;16775dup, g.16810T>A, g.16885C>G) were detected in 16 families affecting primarily exon 3 (6/13) of the C1INH gene. In the 3 remaining families, known mutations were identified affecting primarily exon 8 (2/3).

Angioedema↗
PubMed2000

Dominant sensitization variants of human O(6)-methylguanine-DNA-methyltransferase obtained by a mutational screen of surface residues.

A scanning mutagenesis experiment was performed on human O(6)-methylguanine methyltransferase (hMGMT), directed largely at non-conserved surface residues that have not previously been studied. Variants typically contained two or more substitutions. Two of the 16 variants characterized in detail are inactive for methyltransfer, but increase the cytotoxicity and mutagenic effects of methylating agents. This phenotype is reminiscent of a variant (C145A) that has a mutation in the methyl-accepting cysteine. C145A is inactive, but reportedly binds methylated DNA and confers sensitivity to methylating agents. The sensitization phenotype of the two new variants is more striking in strains that are wild-type for DNA repair than in strains that are deficient for repair, suggesting that these proteins inhibit functional DNA repair proteins by competitively binding to methylated DNA. Both variants have multiple substitutions in the last helix of the protein. These results suggest that the C-terminal helix is necessary for methyltransfer activity, but not for methylguanine-specific binding.

Amino Acid Sequence↗
PubMed1995

Restriction endonuclease fingerprinting (REF): a sensitive method for screening mutations in long, contiguous segments of DNA.

Restriction endonuclease fingerprinting (REF) is a modification of single-strand confirmation polymorphism (SSCP) that was developed to detect the presence of essentially all mutations in a 1-kb segment. To test REF, a 1-kb segment of the human factor IX gene was amplified with PCR and digested with each of five groups of restriction endonucleases. The endonucleases in each group were chosen so that the average size of the fragments was about 150 bp. After separate digestions, the products were mixed, 5' end-labeled with T4 polynucleotide kinase, denatured and electrophoresed under nondenaturing conditions. Each lane screened 1 kb and typically contained 68 segments (6.8 fragments per average digestion x 5 digestions x 2 strands). REF was performed with 5.6% polyacrylamide and 7.5% GeneAmp at temperatures of either 23 degrees or 8 degrees C. Point mutations resulted in the gain or loss of a restriction site in 21% of 24 test mutations (informative restriction component). In cases in which the restriction component was not informative, mutations were detected if any of the five mutation-containing restriction fragments (producing 10 single-stranded segments) displayed abnormal mobility (SSCP component). The average efficiency per single-stranded segment of the SSCP component for the 24 point mutations ranged from 49% for polyacrylamide at 23 degrees C to 68% with GeneAmp at 8 degrees C. REF detected 96% of the mutations with polyacrylamide at 23 degrees C and 100% with GeneAmp at 23 degrees or 8 degrees C. GeneAmp at 23 degrees and 8 degrees C also detected 100% of a subsequent blinded sample that contained normal controls and 27 different point mutations.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed2004

Evaluation of mutation screening as a first line test for the diagnosis of the primary hyperoxalurias.

BACKGROUND: A definitive diagnosis of primary hyperoxaluria type 1 (PH1) and primary hyperoxaluria type 2 (PH2) requires the measurement of alanine:glyoxylate aminotransferase (AGT) and glyoxylate reductase (GR) activities, respectively, in a liver biopsy. We have evaluated a molecular genetic approach for the diagnosis of these autosomal-recessive diseases. METHODS: Polymerase chain reaction (PCR) was used to detect three common mutations in the AGXT gene (c.33_34insC, c.508G>A, and c.731T>C) and one, c.103delG, in the GRHPR gene in DNA samples from 365 unrelated individuals referred for diagnosis of PH1 and/or PH2 by liver enzyme analysis. RESULTS: One or more of these mutations was found in 183 (68.8%) biopsy proven cases of PH1 and PH2 with a test negative predictive value of 62% and 2%, respectively. 102 (34.1%) patients were homozygous or compound heterozygous, making a molecular diagnosis possible. Age of onset and presenting features were similar in patients homozygous for any of the four mutations. Of the AGXT homozygotes, only the c.508G>A mutant was associated with significant AGT catalytic activity and in two of these activity was in the low normal range, possibly reflecting variation in mitochondrial content of the biopsy as this particular mutation is associated with mitochondrial mistargeting. CONCLUSION: Limited mutation analysis can provide a useful first line test for PH1 and PH2 in patients in whom primary hyperoxaluria is suspected and in whom secondary causes have been excluded. Those patients in whom a single mutation, or no mutation, is found can then be selectively targeted for liver biopsy.

Age Factors↗
PubMed2000

RNA-based mutation screening in German families with Sjögren-Larsson syndrome.

Sjögren-Larsson syndrome (SLS) is a rare autosomal recessively inherited disorder characterised by mental retardation, spasticity and ichthyosis. SLS patients have a profound deficiency in fatty aldehyde dehydrogenase (FALDH) activity. The human cDNA of FALDH has been shown to map to the SLS locus on chromosome 17p11.2. Here we describe a method based on reverse transcriptase-polymerase chain reaction (RT-PCR) and protein truncation test to identify mutations in the FALDH gene in nine German SLS families. Using this detection system both disease-causing mutations were found in eight of the nine SLS families examined (17/18 chromosomes). Seven different mutations were identified: an exon 2 skipping due to exon 2 splice donor mutation; two different exon 3 splice donor mutations resulting in combined exon 2 and 3 skipping; a 906delT deletion in exon 6; a genomic deletion of about 6 kb including exon 9; a 1277T > G transversion resulting in a Leu426Ter nonsense mutation; and a 1297delGA deletion. Two of the mutations identified, the genomic exon 9 deletion and the 906delT in exon 6 affected five out of seven SLS patients from a small region of Northern Bavaria. Therefore these two mutations accounted for 71% (10/14 chromosomes) of Bavarian SLS alleles and so far have not been described in SLS families from other countries. Our findings do not support our 'historical' hypothesis, that a possible region clustering in Northern Bavaria could be due to the presence of Swedish soldiers during the 30 Years War (1618-1648), but suggest that two mutations causing SLS syndrome originated in Northern Bavaria.

Aldehyde Oxidoreductases↗
PubMed1998

Complete mutational screening of the CFTR gene in 120 patients with pulmonary disease.

In order to determine the possible role of the cystic fibrosis transmembrane regulator (CFTR) gene in pulmonary diseases not due to cystic fibrosis, a complete screening of the CFTR gene was performed in 120 Italian patients with disseminated bronchiectasis of unknown cause (DBE), chronic bronchitis (CB), pulmonary emphysema (E), lung cancer (LC), sarcoidosis (S) and other forms of pulmonary disease. The 27 exons of the CFTR gene and their intronic flanking regions were analyzed by denaturing gradient gel electrophoresis and automatic sequencing. Mutations were detected in 11/23 DBE (P = 0.009), 7/25 E, 5/27 CB, 5/26 LC, 5/8 S (P = 0.013), 1/4 tuberculosis, and 1/5 pneumonia patients, and in 5/33 controls. Moreover, the IVS8-5T allele was detected in 6/25 E patients (P = 0.038). Four new mutations were identified: D651N, 2377C/T, E826K, and P1072L. These results confirm the involvement of the CFTR gene in disseminated bronchiectasis of unknown origin, and suggest a possible role for CFTR gene mutations in sarcoidosis, and for the 5T allele in pulmonary emphysema.

Adult↗
PubMed2000

Major improvement in the efficacy of BRCA1 mutation screening using morphoclinical features of breast cancer.

A family history of breast and/or ovarian cancer is the main criterion used in screening BRCA1 gene carriers. However, ascertaining a patient's family history is a difficult task, which significantly restricts the use of this parameter in clinical practice. Alternative individual criteria that can be used to identity BRCA1 gene carriers would, therefore, be of great value. In this context, it was recently established that BRCA1-associated breast cancers (BRCA1-BCs) show a specific morphoclinical pattern. In multivariate analyses, the two most discriminant morphoclinical parameters available for establishing the BRCA1 status, in addition to an early age at onset, are estrogen receptor negativity (ER-) and poor tumor differentiation (TD3). Here we tested the efficacy of these two morphological parameters as BRCA1 mutation indicators and investigated their economic impact, in a population-based survey on a series of women who developed invasive breast cancer by the age of 35 years, regardless of their family history. A high rate of 28.6% of BRCA1 mutations was found to have occurred in the group of tumors with both ER- and TD3 versus only 3.6% in tumors with other profiles (P = 0.007; odds ratio, 10.8). When the sole criterion used was early onset by the age of 35 years, the mutation rate was found to be 8.6%. The resulting cost of testing only women with ER- and TD3 tumors worked out at 30% that of testing the whole population of women with cancer by the age of 35 years, and the sensitivity was found to be of 66%. Lastly, the family history of ER- and TD3 cases with a BRCA1 mutation was investigated retrospectively, and none of these cases was found to have a particularly extensive family history of breast and/or ovarian cancer. The use of these morphological features of BRCA1-BCs that are currently typed in clinical practice, therefore, provides a helpful and cost-effective tool for those making decisions about genetic screening. This strategy makes it possible to identify gene carriers who would be overlooked using current criteria.

Adult↗