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At least 343 records · Page 19Linked to original sources
PubMed1996

Cancer risk in families with hereditary nonpolyposis colorectal cancer diagnosed by mutation analysis.

BACKGROUND & AIMS: Hereditary nonpolyposis colorectal cancer is characterized by early-onset colorectal cancer and the occurrence of various other cancers. The recent isolation of four mismatch repair genes responsible for hereditary nonpolyposis colorectal cancer allows for the identification of carriers within affected families. The purpose of this study was to assess the age-specific cancer risk in a large series of gene carriers. METHODS: Thirty-four families were studied by mutation analysis. In 19 of these families, pathogenic mutations were found at hMSH2 or hMLH1. Of 382 relatives, 124 had a mutation in hMLH1 and 86 in hMSH2. RESULTS: The lifetime risk of colorectal cancer was the same in both groups of gene carriers (80%). The risk of endometrial cancer was greater in hMSH2 gene carriers compared with hMLH1 gene carriers (61% vs. 42%), but the difference was not statistically significant. A very high relative risk of cancer of the small bowel (relative risk of >100) was observed in carriers of either gene. Only the carriers of hMSH2 mutations had a significantly increased relative risk of cancer of the urinary tract (kidney and ureter) (relative risk of 75.3), stomach (relative risk of 19.3), and ovaries (relative risk of 8.0). CONCLUSIONS: This study provides estimates of cancer risk that may contribute to the appropriate management of gene carriers within families with hereditary nonpolyposis colorectal cancer.

Adolescent↗
PubMed2003

A different molecular interaction of bradykinin and the synthetic agonist FR190997 with the human B2 receptor: evidence from mutational analysis.

Binding affinity at the [3H]-BK binding site and activity as inositol phosphate (IP) production by the peptide bradykinin (BK) and the nonpeptide FR190997 were studied at wild-type or point-mutated human B2 receptors (hB2R) expressed in CHO cells. The effect of the following mutations were analyzed: E47A (TM1), W86A and T89A (TM2), I110A, L114A and S117A (TM3), T158A, M165T and L166F (TM4), T197A and S211A (TM5), F252A, W256A and F259A (TM6), S291A, F292A, Y295A and Y295F (TM7), and the double mutation W256A/Y295F. As the wild-type receptor-binding affinity of FR190997 was 40-fold lower than BK, whereas their agonist potency was comparable, both agonists produced similar maximal effects (Emax). Mutations were evaluated as affecting the affinity and/or efficacy of FR190997 compared with BK. Two mutations were found to impair the agonist affinity of both agonists drastically: W86A and F259A. BK agonist affinity (pEC50) was reduced by 1400- and 150-fold, and that of FR190997 was reduced by 400- and 25-fold, at the W86A and F259A mutant B2 receptors, respectively. Contrary to BK, the affinity of FR190997 was selectively decreased at I110A, Y295A, and Y295F mutants (>103-fold), and a different efficacy was measured at the Y295 mutants, FR190997 being devoid of the capability to trigger IP production at Y295A mutant. L114A, F252A, and W256A selectively impaired the efficacy of FR190997, whereas its binding affinity was not affected. As a consequence, FR190997 behaved as a high-affinity antagonist in blocking the IP production induced by BK. The lack of capability of FR190997 to activate or to bind the double mutant W256A/Y295F suggests that these residues are part of the same binding site, which is also important for receptor activation by the nonpeptide ligand. Overall, by means of mutational analysis, we indicate an hB2R recognition site for the nonpeptide agonist FR190997 (between TM3, 6, and 7), different from that of BK, and show that in the same binding crevice some mutations (L114, W256, and F252) are selectively responsible for the agonist properties of only FR190997.

Animals↗
PubMed1997

Mutation analysis of five Japanese families with Wiskott-Aldrich syndrome and determination of the family members' carrier status using three different methods.

Mutation analysis for five families with Wiskottt-Aldrich syndrome was performed. The mutations found were two missense mutations, two one-base deletion mutations, and a large deletion mutation in the WASP gene. The three mutations had been reported before, but the remaining two were new. We used the mutation information to determine the carrier status of the female relatives of the patients. Three different approaches were taken depending on the type of mutation, and the carrier determination was successfully performed.

Adult↗
PubMed2007

Mutational analysis of PTPRT phosphatase domains in common human cancers.

A recent report revealed that the protein-tyrosine phosphatase, receptor-type, T (PTPRT) gene is somatically mutated in several types of human cancer, suggesting that the mutated PTPRT gene is a tumor suppressor gene in human cancers. However, because previously the mutational search has focused primarily on colon cancers, data on PTPRT mutations in other types of human cancer have largely been lacking. Here, we performed a mutational analysis of the PTPRT phosphatase domain by polymerase chain reaction-based single-strand conformation polymorphism (PCR-SSCP) assay in 345 cases of common human cancers, including colon carcinomas, hepatocellular carcinomas, acute leukemias, gastric carcinomas, breast carcinomas and non-small cell lung cancers. We detected PTPRT phosphatase domain mutations in 1 of 105 colon carcinomas (1%) and 1 of 48 gastric carcinomas (2%), but none in acute leukemias, hepatocellular carcinomas, breast carcinomas and non-small cell lung cancers. The PTPRT mutation detected in the colon carcinoma was a missense mutation and the mutation in the gastric carcinomas was a splice-site mutation. Contrary to the previous report on the frequent PTPTR phosphatase domain mutations in colon cancers, this study demonstrated that the somatic mutation of the PTPRT phosphatase domain rarely occurred in common human cancers. The data suggested that alterations of the PTPRT-mediated signaling pathway by PTPRT phosphatase domain mutation may not play a critical role in the development of common human cancers.

Carcinoma↗
PubMed1998

Genomic structure of a human holocytochrome c-type synthetase gene in Xp22.3 and mutation analysis in patients with Rett syndrome.

The human holocytochrome c-type synthetase (HCCS) gene is located on Xp22.3 and is one of the genes identified in a 450-Kb region deleted in the neurodevelopmental disorder microphthalmia with linear skin defects. Several other developmental disorders with or without a neurological phenotype have been linked to Xp22.3. This region of the X chromosome was also found to be concordant in patients with Rett syndrome (RTT)in previously performed exclusion mapping. Based on its chromosomal location and its role in the mitochondrial respiratory chain, we analyzed HCCS as a candidate gene for RTT. The genomic structure of this gene, which occupies an 11-Kb region and consists of seven exons, was determined. All intron-exon boundaries were sequenced and primers were designed for polymerase chain reaction (PCR) amplification of each coding exon. PCR-amplified products from genomic DNA isolated from 20 RTT patients were screened for mutations using heteroduplex analysis. No mutations were detected. The genomic characterization of this gene will allow us to perform mutation analysis for other inherited disorders linked to this region.

Base Sequence↗
PubMed1995

Mutational analysis of potato yellow mosaic geminivirus.

Mutations have been inserted into the virion and complementary sense ORFs encoding proteins with M(r)s in excess of 9 kDa of both DNA A and DNA B of potato yellow mosaic geminivirus (PYMV). Wild-type and mutant monomeric clones were tested for their ability to replicate, produce PYMV-specific DNA, spread and cause symptoms in Nicotiana benthamiana plants following biolistic inoculation. Dimeric clones of the DNA A mutants were also investigated by agroinoculation of leaf discs. In contrast to N. benthamiana plants agroinoculated with PYMV DNA A, in which the wild-type DNA A component was capable of limited independent replication and spread, both excised DNA A and B components were required for DNA replication and symptom development in plants inoculated by the biolistic method. Mixtures of both genomic components were also infectious for potato plants following biolistic inoculation. Mutations in ORFs AL1, AL2, BR1 and BL1 resulted in clones incapable of infecting N. benthamiana plants. However, the AL2 mutation, but not the AL1 mutation, allowed viral DNA replication in leaf discs. Mutations to both the AR1 and AL3 ORFs produced clones which were infectious in plants but showed a considerable delay in the production of attenuated symptoms as compared to wild-type infections. Mutating the AL3 ORF dramatically reduced viral DNA replication in both whole plants and leaf discs. Mutations to the AL4 ORF produced clones which were as infectious for both N. benthamiana and potato plants as the wild-type clones. Our results are compared with those from mutagenesis studies on related bipartite geminiviruses.

Cloning, Molecular↗
PubMed2001

Deletion mapping of chromosome 16q24 in hepatocellular carcinoma in Taiwan and mutational analysis of the 17-beta-HSD gene localized to the region.

Human chromosome band 16q24 commonly undergoes loss of heterozygosity (LOH) in human hepatocellular carcinoma (HCC). To further localize the region of deletion on 16q24 and to evaluate the genetic role of 17-beta-HSD, which is near 16q24, in HCC, we examined the pattern of loss of heterozygosity in 88 HCC patients. DNAs from 88 pairs of HCCs and corresponding non-tumor parts were prepared. Loss of heterozygosity on chromosomes 16q24 was investigated by 11 sets of microsatellite markers. Mutation analysis of type II 17-beta-HSD was performed by automatic sequencing. LOH on 16q24 for at least 1 locus was found in 43 of the 88 tumor DNAs (49%). Three non-overlapping regions of frequent LOH were defined in these 43 tumors with partial deletions. The first region was between D16S516 loci and D16S507, encompassed by a 1-cM region, defined by the D16S504. The second region was defined by the 17HSDB2 locus between D16S505 and D16S422, encompassed approximately by a 1-cM region. The third region was between D16S520 and D16S413, defined by D16S3048, encompassed approximately by a 4-cM region. Homozygous deletions of any exons in 17HSDB2 gene were identified in 7 of 27 cases (26%). Automated sequencing analysis of 17HSDB2 failed to demonstrate mutations in any of these specimens. Our data suggest that the 17HSDB2 locus is a frequent target of deletion in HCC but the inactivation of 17HSDB2 may not involve sequence mutations. Furthermore, the presence of the other 2 frequent LOH regions suggest that the putative tumor suppressor genes at these locations might be involved in the development of HCC.

17-Hydroxysteroid Dehydrogenases↗
PubMed1998

Mutation analysis of the phenylalanine hydroxylase gene and its clinical implications in two Japanese patients with non-phenylketonuria hyperphenylalaninemia.

We describe a mutation analysis for the phenylalanine hydroxylase gene and the clinical outcome of two Japanese patients with non-phenylketonuria (PKU) hyperphenylalaninemia (serum phenylalanine level below 600 mumol/l under a free diet) detected by a mass-screening program. Single strand conformation polynorphism analysis and direct sequencing of their genomic DNAs revealed that non-PKU hyperphenylalaninemia resulted from compound heterozygosity for a mutation causing classical PKU and a mutation with a milder effect on phenylalanine hydroxylase activity. The mutations were R241C and R243Q in exon 7, and R413P in exon 12. The mutation genotypes of the two patients were R241C/R243Q and R241C/R413P. It has been demonstrated that homozygosity for the R243Q or R413P mutation is associated with a severe phenotype of PKU and low in vitro expression activity. In contrast, the R241C mutation has much less effect on phenylalanine hydroxylase activity. The metabolic consequence of each variant allele was confirmed by a phenylalanine loading test in the patients and their parents. The patients achieved normal results in all intellectual and neurologic tests. Brain magnetic resonance imaging revealed no abnormalities. The dietary restriction was continued until 10 years of age in order to maintain the serum phenylalanine level below 400 mumol/l. The genetic analysis to distinguish non-PKU hyper-phenylalaninemia from classical PKU helps to determine the principles of dietary management in the early infantile period.

Adolescent↗
PubMed2004

[Mutational analysis of the MECP2 gene by direct sequencing in Hungarian patients with Rett syndrome].

INTRODUCTION: Rett syndrome is an X-linked neurodevelopmental disorder characterized by loss of acquired skills and stereotypical hand movements. Mutations in the gene encoding methyl-CpG-binding protein 2 have been identified as cause of Rett syndrome in 1999. AIM: The authors initialized mutation screening of this gene in Hungarian patients identified on the base of clinical manifestation in various institutes. So far 25 patients were examined who were supposed to have Rett syndrome. METHOD: Total genomic DNA was extracted from peripheral blood with routine desalting method for mutation analysis. The three coding regions of the gene were amplified with primer pairs described. The PCR products were analysed by direct sequencing. RESULTS: Mutations in methyl-CpG-binding protein 2 gene were found in 17/25 cases (68%). This rate of mutation among Rett patients corresponds well with the findings of other studies. Two novel mutations were found. In the first patient whose history was characterized by a slower than normal progression, a G insertion at the base position 276 of exon 3 was detected, while in the second child a double deletion (191, and 9 bases, resp.) in exon 4 was identified.

Adolescent↗
PubMed1994

Mutational analysis of the NH4+-nitrogen controls that regulate ammonium transport activity, heterocyst differentiation, nitrogenase activity and the heterocyst-spacing pattern in the cyanobacterium Nostoc muscorum.

Mutational analysis of the genetic determinants mediating NH(4+)-nitrogen regulating effects on NH(4+)-transport activity, heterocyst differentiation, nitrogenase activity and heterocyst pattern formation was carried out in Nostoc muscorum. Evidence suggested the operation of three separate genetic determinants in such nitrogen control; one mediating NH(4+)-repression control on both heterocyst formation and NH(4+)-transport activity, a second (Nif-R) mediating NH(4+)-repression control on nitrogenase synthesis/activity and a third (Pat-R) essential for intercalary heterocyst formation/distribution. Ammonia itself functioned as repressor signal of heterocyst formation and nitrogenase synthesis/activity and the glutamine synthetase enzyme played no role in the repression/derepression control of heterocyst development and functional nitrogenase formation.

Bacterial Proteins↗
PubMed2002

Maple syrup urine disease: mutation analysis in Turkish patients.

Maple syrup urine disease (MSUD), the most frequently occurring organic acidaemia in Turkey, is caused by a deficiency of the activity of branched-chain keto acid dehydrogenase enzyme (BCKAD) complex. Mutation analysis of the E1alpha, E1beta, and E2 genes of the BCKAD complex in 12 Turkish MSUD patients yielded three disease-specific mutations and a polymorphism in the E1alpha gene, none in the E1beta gene and one mutation in the E2 gene. Among them, three missense mutations (Q80E, C213Y, T106M) and the F280F polymorphism occurring in the E1alpha gene and the splice site mutation (IVS3 - 1G>A) in the E2 gene were novel. Three of the missense mutations and the splicing mutation occurred homozygously and caused classical MSUD. One patient carried the splicing mutation homozygously and the T106M mutation in the heterozygous state; this patient is the first case having simultaneously two different mutations in two different genes in the BCKAD complex. IVS3 - IG>A splicing mutation detected on the E2 gene causes deletion of the first 14 bp of exon 3 in the mutant mRNA extending between 190 and 204 nt. The deletion spans the cleavage point between mitochondrial targeting and lipoyl-bearing site of the E2 protein.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed2002

Mutational analysis of StAR gene in adrenal tumors.

Adrenal adenomas and carcinomas are mostly monoclonal, suggesting that a genetic alteration in a progenitor cell may contribute to their development. However, the molecular pathogenesis of these tumors still remains unclear. It has been already excluded that activating mutations of the ACTH receptor or of G protein stimulator alpha sub-units, affecting cAMP pathway, is involved in the tumorigenesis. Therefore, this work has been focused on post-transductional (ACTH) signal alterations and in particular on the mutational analysis of the Steroid Acute Regulatory protein (StAR) gene to verify whether somatic mutations or genomic polymorphisms of this gene may be correlated with adrenal tumorigenesis. Tissue DNA was extracted from 40 functional and non-functional adrenocortical tumors that were removed from patients aged between 17 and 72 years (mean 43 +/- 4). Blood DNA was obtained from 24 patients (aged between 26 and 70 years) affected by adrenal tumors and from 100 healthy subjects without radiological and clinical evidence of adrenal masses, aged between 25-35 years (90 Caucasians and 10 Africans). The DNA was used as the template for the amplification of the StAR gene using the polymerase chain reaction. The amplified DNA of each exon of the StAR gene was purified and sequenced in automatic sequenciator. With the exception of exon 5 showing in codon 203 an homozygous missense mutation, the sequence of the other exons of the StAR gene resulted normal in all tumors studied. The same homozygous mutation (Asp203Ala) was observed in the sequence of exon 5 performed on genomic DNA of the 24 affected patients and in the control subjects. The homozygosity of the mutation observed in all patients (either in tissue or blood samples) and in control subjects, independently of their ethnic origin, led us to suggest that the Asp203Ala cannot be considered as mutation or as polymorphism, but that it must be considered as a mistake in the sequence entered in the Genbank, which needs to be modified accordingly. These data, and those up to now reported in the literature, allow us to suggest that mutations of the gene coding for the protein involved in the initial step of the steroidogenesis could not be considered as a possible cause for the development of adrenal tumors.

Adenoma↗
PubMed1990

Point mutation analysis of the Xenopus laevis RNA polymerase I core promoter.

The core region of the Xenopus laevis pre-ribosomal RNA promoter was subjected to point mutation analysis. A total of 27 point mutants within a 78 base pair region from -64 to +14, (relative to the start of transcription at +1), were assayed by oocyte microinjection. The results locate the 3' boundary of the core promoter at +4 and the 5' boundary at between -33 and -39 and suggest that this region of the Xenopus promoter is generally similar in organisation to mammalian core promoters. In particular, the conserved guanidine nucleotides at -7 and -16 are clearly essential for promoter function. The data suggest that interactions between the transcription machinery and the promoter occur in four distinct regions around +2 to +4, -7, -17 to -20 and -28 to -33. This particular periodicity of functionally important nucleotides is consistent with a model in which all protein-DNA interactions take place from predominantly one side of the DNA helix.

Animals↗
PubMed2006

Diagnostic mutational analysis of MECP2 in Korean patients with Rett syndrome.

Rett syndrome (RTT) is an X-linked dominant neurodevelopmental disorder affecting 1 per 10,000-15,000 female births worldwide. The disease-causing gene has been identified as MECP2 (methyl-CpG-binding protein 2). In this study, we performed diagnostic mutational analysis of the MECP2 gene in RTT patients. Four exons and a putative promoter of the MECP2 gene were analyzed from the peripheral blood of 43 Korean patients with Rett syndrome by PCR-RFLP and direct sequencing. Mutations were detected in the MECP2 gene in approximately 60.5% of patients (26 cases/43 cases). The mutations consisted of 14 different types, including 9 missense mutations, 4 nonsense mutations and 1 frameshift mutation. Of these, three mutations (G161E, T311M, p385fsX409) were newly identified and were determined to be disease-causing mutations by PCR- RFLP and direct sequencing analysis. Most of the mutations were located within MBD (42.3%) and TRD (50%). T158M, R270X, and R306C mutations were identified at a high frequency. Additionally, an intronic SNP (IVS3+23C>G) was newly identified in three of the patients. IVS3+23C>G may be a disease-related and Korea-specific SNP for RTT. L100V and A201V are apparently disease-causing mutations in Korean RTT, contrary to previous studies. Disease-causing mutations and polymorphisms are important tools for diagnosing RTT in Koreans. The experimental procedures used in this study should be considered for clinical molecular biologic diagnosis.

Base Sequence↗
PubMed2005

Mutation analysis of COL9A3, a gene highly expressed in the cochlea, in hearing loss patients.

cDNA microarray analysis indicated that COL9A3 is one of the highly expressed genes in the cochlea. This suggests that collagen type IX has a crucial functional role in the inner ear and may be a candidate gene for hearing loss. Mutation analysis was carried out to find possible disease-causing mutations in this gene. The direct-sequencing method was applied to the COL9A3 gene in 159 non-syndromic sensorineural deafness patients and 150 normal controls. Two possible disease-causing mutations were identified: an in-frame deletion of three amino acid residues (G181-P183 del) and a missense mutation (D617E). The patients with the mutations showed a moderate progressive bilateral sensorineural hearing impairment in all frequencies. The present data indicate that mutations of COL9A3 may cause non-syndromic hearing impairment.

Amino Acid Sequence↗
PubMed2006

HRAS mutation analysis in Costello syndrome: genotype and phenotype correlation.

Costello syndrome is a rare condition comprising mental retardation, distinctive facial appearance, cardiovascular abnormalities (typically pulmonic stenosis, hypertrophic cardiomyopathy, and/or atrial tachycardia), tumor predisposition, and skin and musculoskeletal abnormalities. Recently mutations in HRAS were identified in 12 Japanese and Italian patients with clinical information available on 7 of the Japanese patients. To expand the molecular delineation of Costello syndrome, we performed mutation analysis in 34 North American and 6 European (total 40) patients with Costello syndrome, and detected missense mutations in HRAS in 33 (82.5%) patients. All mutations affected either codon 12 or 13 of the protein product, with G12S occurring in 30 (90.9%) patients of the mutation-positive cases. In two patients, we found a mutation resulting in an alanine substitution in position 12 (G12A), and in one patient, we detected a novel mutation (G13C). Five different HRAS mutations have now been reported in Costello syndrome, however genotype-phenotype correlation remains incomplete.

Abnormalities, Multiple↗
PubMed2006

Mutational analysis of Kir6.1 in Japanese patients with coronary spastic angina.

The etiology of coronary spastic angina (CSA) remains uncertain. Mice lacking the gene encoding the inwardly rectifying K(+) channel Kir6.1 were developed as an animal model of CSA. We investigated whether mutation in the coding region of the Kir6.1 gene is detected in Japanese patients with CSA. The study population included 19 Japanese patients with CSA (10 men and 9 women with a mean age of 61+/-14 years). Mutational analysis of the coding region of Kir6.1 was performed by direct sequencing. We found no missense or nonsense mutations in these samples, but we found in one female CSA patient, a single base substitution (C to T) at nucleotide position 111 in exon 2 of the coding region, which was heterozygous and did not cause amino acid substitution (Ile37Ile, silent mutation). In the remaining 18 patients, no base substitution was detected in the coding region of the Kir6.1 gene. No mutation that alters primary structure of Kir6.1 was detected in Japanese patients with CSA. The results indicate that abnormality in the primary structure of Kir6.1 may not be involved in the genetic pathogenesis of CSA in humans.

Aged↗
PubMed2005

Mutational analysis of the NPHP4 gene in 250 patients with nephronophthisis.

Nephronophthisis (NPH), a recessive cystic kidney disease, is the most frequent genetic cause for end-stage renal disease in the first two decades of life. Mutations in three genes (NPHP1, 2, and 3) were identified as causative. Extrarenal manifestations are known, such as retinitis pigmentosa (Senior-Loken syndrome, SLS) and ocular motor apraxia type Cogan. Recently, we identified a novel gene (NPHP4) as mutated in NPH. To date, a total of only 13 different NPHP4 mutations have been described. To determine the frequency of NPHP4 mutations, we performed mutational analysis by direct sequencing of all 30 NPHP4 exons in 250 different patients with isolated NPH, SLS, or Cogan syndrome ascertained worldwide over 14 years. We identified 23 novel NPHP4 sequence variants in 26/250 different patients (10%). Interestingly, we detected homozygous or compound heterozygous mutations of NPHP4 in only 6/250 different patients (2.4%), but only one heterozygous NPHP4 sequence variant in 20/250 different patients (8%). In the six patients with two NPHP4 mutations, 5/8 mutations (63%) were likely loss-of-function mutations, whereas in the 20 patients with only one sequence variant, only 1/20 (5%) was a likely loss-of-function (i.e., truncating) mutation. We conclude that: i) two recessive mutations in NPHP4 are a rare cause of nephronophthisis; ii) single heterozygous NPHP4 sequence variants are three times more prevalent than two recessive mutations; iii) there is no genotype/phenotype correlation; iv) there must exist further genes causing nephronophthisis, since in 224/250 (90%) patients, no sequence variants in either of the four NPH genes were detected.

Adolescent↗