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At least 1,369 records · Page 76Linked to original sources
PubMed1998

Compound heterozygosity for a new (S259G) and a previously described (G188E) mutation in lipoprotein lipase (LpL) as a cause of chylomicronemia. Mutations in brief no. 183. Online.

Familial chylomicronemia is an autosomal recessive disease characterised by fasting triglyceridemia and an absence of lipoprotein lipase (LpL) activity in post-heparin plasma. The disease is a result of mutation in either the lipoprotein lipase (Lpl) gene or in the apoCII gene which codes for an essential co-factor. To date, over 80 mutations in the LpL gene have been reported. The proband, a 30 month old female, presented with fasting triglycerides of 3192 mg/dl, and no detectable LpL mass or activity in post-heparin plasma. Sequencing of all of the exons and exon/intron boundaries of the LpL gene showed that she was a compound heterozygote with G-A transitions in codon 188 (G188E:GGG to GAG) generating an avall restriction site and in codon 259 (S259G:AGT to GGT) generating a bssKI site. Restriction digests confirmed the mutations and determined the incidence within the family. The father (55%LPL activity), paternal aunt (82%) and paternal grandmother (29%) were all heterozygous for the S259G mutation whilst her sister (55%), mother (73%) and maternal grandfather (45%) were heterozygous for the G188E mutation. The maternal grandmother (114%) was unaffected.

Female↗
PubMed1998

T426I a new mutation in the thyroid hormone receptor beta gene in a sporadic patient with resistance to thyroid hormone and dysmorphism. Mutations in brief no. 192. Online.

Resistance to thyroid hormone (RTH) is a rare inherited autosomal syndrome caused by mutations in the thyroid hormone receptor beta (TRb) gene. Although RTH is generally a familiar disease, 15% of sporadic cases have been also reported. So far, about 80 different mutations of TRb gene have been identified in patients affected by RTH. All these mutations localize to the binding domain and most of them cluster within two "hot spots" (codons 310-349 and codons 429-460). Here we describe in a patient with RTH, a new mutation in codon 426 (T426I) of the TRb gene leading to a threonine to isoleucine substitution. This is a "de nova" mutation which localizes in the so-called "cold" region, outside the two known "hot spots". The patient had the hallmark of RTH: elevated FT3 and FT4, normal TSH, and clinical features of both hypo and hyperthyroidism. Moreover, several dysmorphisms were present including triangular face appearance, synophris, low set ears, micrognathia with malocclusion, large upper incisors and apparent lack of lower cuspids which have not previously described in RTH patients.

Craniofacial Abnormalities↗
PubMed2001

Perinatal hypophosphatasia: radiology, pathology and molecular biology studies in a family harboring a splicing mutation (648+1A) and a novel missense mutation (N400S) in the tissue-nonspecific alkaline phosphatase (TNSALP) gene.

We report on a postmortem diagnosis of perinatal lethal hypophosphatasia, an inborn error of metabolism characterized by a liver/bone/kidney alkaline phosphatase (ALP)-related defective bone mineralization due to mutations in the tissue-nonspecific alkaline phosphatase (TNSALP) gene. Radiological and pathological studies identified a perinatal lethal hypophosphatasia showing a generalized bone mineralization defect including asymmetry of the cervical vertebral arches in a 22 +4 weeks' gestation fetus. Both parents revealed low serum ALP activities supporting the diagnosis. Sequencing analysis of the TNSALP gene showed two heterozygous mutations, 648+1A, a mutation affecting the donor splice site in exon 6, and N400S, a novel missense mutation in exon 11, located near the active site and very close to histidins 364 and 437, two crucial residues of the active site. Sequencing of exons 6 and 11 in the parents showed that 648+1A was from maternal origin and N400S from paternal origin. DNA-based prenatal testing in the subsequent pregnancy following a chorionic villous sampling performed at 10 weeks of gestation showed no mutation and a healthy infant was born at term.

Alkaline Phosphatase↗
PubMed2002

Low mutation incidence in polymorphic noncoding short mononucleotide repeats in gastrointestinal cancer of the microsatellite mutator phenotype pathway.

Frameshifts in short mononucleotide tracts (SMT) in genes, such as TGFbetaRII and BAX, are common in gastrointestinal tumors of the microsatellite mutator phenotype (MMP). The significance of less common mutations has been recently challenged because frequencies as high as 50% were reported in some noncoding SMTs in MMP colon cancer cell lines (L. Zhang, et al., Cancer Res., 61: 3801-3805, 2001). We did not confirm these findings after examining >50 MMP gastrointestinal cancers for mutations in eight SMT loci with the highest reported frequencies. In three of these loci, no clonal mutations were detected, and they were infrequent (2.9-6.7%) in the other five. Length polymorphisms are frequent (25.7-43.9%) in one-half of these SMTs, suggesting an explanation for the discrepancy. Because of the peculiar features of MMP tumors, low prevalence of mutations in cancer genes may not be a disqualifying criterion for their functionality.

Gastrointestinal Neoplasms↗
PubMedDate not supplied

P53 mutation but not p16/MTS1 mutation occurs in intraductal papillary mucinous tumors of the pancreas.

BACKGROUND/AIMS: Intraductal papillary mucinous tumors of the pancreas are rare lesions, which typically show a benign clinical course. However, some of these tumors have a malignant nature and grow in an invasive manner. The purpose of the study was to determine the prevalence of p53-, p16/MTS1- and K-ras mutations in benign and malignant intraductal papillary mucinous tumors with intent to value their importance for tumor progression. METHODOLOGY: Thirteen different archival tumor specimens were obtained at the Department of Pathology, University of Ulm. Three cases showed an invasive component of the tumor. Genomic DNA was extracted after laser capture microdissection of tumor cells from paraffin-embedded tissue sections. The corresponding sequences of p53 (exon 5, 6, 7, 8) and p16/MTS1 (exon 2) were amplified by polymerase chain reaction and subjected to single strand conformation polymorphism analysis. Codon 12 of K-ras was analyzed by the enrichment polymerase chain reaction-restriction fragment length polymorphism method. Positive samples were further investigated by sequencing. RESULTS: K-ras mutations occurred in benign and malignant intraductal papillary mucinous tumors (4/13), whereas an alteration of the coding p53 gene sequence could only be detected in the intraductal and invasive component of one malignant tumor. None of the tissue specimens revealed mutations in exon 2 of p16/MTS1. CONCLUSIONS: In contrast to K-ras mutations, alterations in the p53 gene may characterize ductal papillary mucinous carcinomas, which could be of major interest for their early diagnosis. The lack of mutations in the p16/MTS1 gene suggests that other genes may be involved in the formation of intraductal papillary mucinous neoplasias.

Biomarkers, Tumor↗
PubMed1992

Mutations in severe, type III von Willebrand's disease in the Dutch population: candidate missense and nonsense mutations associated with reduced levels of von Willebrand factor messenger RNA.

The von Willebrand factor (vWF) genes of nine unrelated, severe, type III von Willebrand's disease (vWD) patients (six of Dutch origin) and four unrelated Dutch type I vWD patients were screened for mutations in exons that contain CGA codons (Arg), which are liable to mutation to TGA stop codons. The nine exons of the vWF gene (3, 8, 9, 10, 28, 31, 32, 43 and 45) that contain all the CGA codons (11 in total) of the vWF cDNA were amplified by the polymerase chain reaction and screened for mutations by single-strand conformation polymorphism analysis, restriction enzyme - and/or nucleotide sequence analysis. Three of the severe vWD patients were found to be heterozygous for a nonsense mutation: CGA Arg 2535-->TGA Stop. Three other severe vWD patients were homozygous for a single nucleotide substitution, AAC Asn 2546-->TAC Tyr. The transcription of these mutated alleles was tested by cDNA dependent amplification of platelet RNA. The level of transcription product was strongly reduced for either mutant allele.

Alleles↗
PubMed1992

Role of p53 mutations in endocrine tumorigenesis: mutation detection by polymerase chain reaction-single strand conformation polymorphism.

To elucidate the molecular basis for endocrine tumorigenesis, p53 mutations in human endocrine tumors were analyzed by using polymerase chain reaction-single strand conformation polymorphism. Exons 5 through 10 of the p53 gene were studied in genomic DNAs from 134 primary endocrine tumors and 6 human endocrine cancer-derived cell lines. Mutations were detected and identified in 4 endocrine tumors, including one parathyroid adenoma and three thyroid carcinoma cell lines. The sites of these mutations were in exons 5 (codon 151 and 152) and 7 (codon 248 and 255). In all of three tumor cell lines, but not in a parathyroid adenoma, the normal allele encoding the p53 gene was lost. However, p53 mutations were not found in any other endocrine tumors or cell lines. Based upon these results, we concluded that the p53 gene may play a role in the tumorigenesis of a limited number of parathyroid adenoma and thyroid cancers, and that the p53 mutation with an allelic loss of the p53 gene is an important factor in malignant tumorigenesis of the thyroid gland.

Base Sequence↗
PubMed2004

LET and ion-species dependence for mutation induction and mutation spectrum on hprt locus in normal human fibroblasts.

We have been studying LET and ion species dependence of RBE in mutation frequency and mutation spectrum of deletion pattern of exons in hprt locus. Normal human skin fibroblasts were irradiated with heavy-ion beams, such as carbon- (290 MeV/u and 135 MeV/u), neon- (230 MeV/u and 400 MeV/u), silicon- (490 MeV/u) and iron- (500 MeV/u) ion beams, generated by Heavy Ion Medical Accelerator in Chiba (HIMAC) at national Institute of Radiological Sciences (NIRS). Mutation induction in hprt locus was detected to measure 6-thioguanine resistant colonies and deletion spectrum of exons was analyzed by multiplex PCR. The LET-RBE curves of mutation induction for carbon- and neon-ion beams showed a peak around 75 keV/micrometers and 155 keV/micrometers, respectively. On the other hand, there observed no clear peak for silicon-ion beams. The deletion spectrum of exons was different in induced mutants among different ion species. These results suggested that quantitative and qualitative difference in mutation occurred when using different ion species even if similar LET values.

Carbon↗
PubMed1992

Low frequency of ras oncogene mutations in Philadelphia-positive acute leukemia and report of a novel mutation H61 Leu in a single case.

Activating ras mutations are frequent (25-60%) in chronic myelomonocytic leukemia (CMML) and in acute myeloid leukemia (AML) (30%), in contrast to chronic myeloid leukemia (CML) in which the incidence is very low (0-3%). This might reflect that the leukemic cell in CML is at a level of differentiation in which ras gene activation is not involved or, alternatively, might be due to the presence in CML of the bcrlabl fused gene. We have analyzed the presence of point mutations in codons 12, 13, 59, 61 and 63 of N-, K-, and H-ras genes, in 26 cases of Philadelphia-chromosome-positive, bcrlabl-positive acute leukemia (Ph+ AL), and in eight CMML cases by using the polymerase chain reaction. Aberrant ras genes were detected in a single Ph+ AL case, and in four out of eight CMML patients. The Ph+ AL showing altered ras allele had an unusual point mutation in H-ras gene, substituting leucine for glutamine. This mutation has not been previously found in any hematological disease. Our findings suggest that ras mutations are probably not involved in the pathogenesis of those leukemias in which blast cells contain bcrlabl oncogene activation.

Codon↗
PubMed2006

Expanding the mutational spectrum in TGFBI-linked corneal dystrophies: Identification of a novel and unusual mutation (Val113Ile) in a family with granular dystrophy.

PURPOSE: To report the clinical and molecular study of a family with an autosomal dominant stromal granular dystrophy of the cornea caused by a novel and unusual TGFBI gene mutation. METHODS: A complete ophthalmological examination, corneal dystrophy phenotype characterization, PCR amplification, and automated nucleotidic sequencing of exons 4, 11,12, 13, and 14 of the TGFBI gene was carried out on the family. DNA from 40 unrelated ethnically matched healthy individuals were analyzed as controls. RESULTS: Corneal dystrophy in two sisters was characterized by multiple grayish-white lesions located in the anterior and mid-stroma. Numerous small sized non-coalescent opacities were observed in the peripheral cornea while fewer larger lesions were apparent towards the central part of the cornea. A heterozygous missense mutation, consisting of a G to A transition at nucleotide position 384 in TGFBI exon 4 that predicts a valine (GTT) to isoleucine (ATT) replacement in residue 113 (Val113Ile) of the TGFBI protein was identified. CONCLUSIONS: This is the most 5' located mutation detected so far in subjects with TGFBI-linked corneal dystrophy. Valine 113 is strictly conserved in TGFBI from several species and we suggest that the phenotype observed in these patients is related to the unusual location of the mutation. Our results expand the mutational spectrum in the group of TGFBI-linked corneal dystrophies.

Adenine↗
PubMed1990

Recurrent mutation, gene conversion, or recombination at the human phenylalanine hydroxylase locus: evidence in French-Canadians and a catalog of mutations.

The codon 408 mutation (CGG----TGG, Arg----Trp) in exon 12 of the phenylalanine hydroxylase (PAH) gene occurs on haplotype 1 in French-Canadians; elsewhere this mutation (R408W) occurs on haplotype 2. A CpG dinucleotide is involved. The finding is compatible with a recurrent mutation, gene conversion, or a single recombination between haplotypes 2 and 1. A tabulation of 20 known mutations at the PAH locus reveals three instances of putative recurrent mutation.

Alleles↗
PubMed1990

Identical G+1 to A mutations in three different introns of the type III procollagen gene (COL3A1) produce different patterns of RNA splicing in three variants of Ehlers-Danlos syndrome. IV. An explanation for exon skipping some mutations and not others.

Identical G+1 mutations in three different introns of the gene for type III procollagen (COL3A1) that cause aberrant splicing of RNA were found in three probands with life-threatening variants of Ehlers-Danlos syndrome. Because the three mutations were in a gene with multiple and homologous exons, they provided an interesting test for factors that influence aberrant splicing. The G+1 to A mutation in intron 16 caused extensive exon skipping, the G+1 to A mutation in intron 20 caused both use of a cryptic splice site and retention of all the intron sequences, and the G+1 to A mutation in intron 42 caused efficient use of a single cryptic splice site. The different patterns of RNA splicing were not explained by evaluation of potential cryptic splice sites in the introns by either their homology with 5'-splice sites from other genes or by their delta G(0)37 values for binding to U1 RNA. Instead, the results suggested that the patterns of aberrant RNA splicing were primarily determined by the relative rates at which adjacent introns were normally spliced.

Adenine↗
PubMed1989

Mutational analysis of the mitochondrial Rieske iron-sulfur protein of Saccharomyces cerevisiae. II. Biochemical characterization of temperature-sensitive RIP1- mutations.

Although the function of the Rieske iron-sulfur protein is generally understood, little is known of how the structure of this protein supports its mechanistic role in electron transfer in the cytochrome bc1 complex. To better understand the structural basis of iron-sulfur protein function, we have undertaken a mutational analysis of the gene encoding this protein and initially isolated five temperature-sensitive iron-sulfur protein mutants (Beckmann, J. D., Ljungdahl, P. O., and Trumpower, B. L. (1989) J. Biol. Chem. 264, 3713-3722). Each of the five ts-rip1- mutants exhibited pleiotropic effects. Although the mutant iron-sulfur proteins manifest several in vitro phenotypes in common, each exhibited unique characteristics. All of the ts-rip1- mutations resulted in membranes with decreased ubiquinol-cytochrome c oxidoreductase activities and decreased thermostability compared to membranes containing wild type iron-sulfur protein. All of the mutations conferred slight but significant resistance to the respiratory inhibitor myxothiazol, and one mutant was hypersensitive to inhibition by UHDBT, a structural analog of ubiquinone. In addition, one of the mutations completely blocks post-translational processing of the iron-sulfur protein, leading to accumulation of pre-iron-sulfur protein in mitochondrial membranes at nonpermissive temperatures. Finally, a mutation 12-amino acid residues away from the carboxyl terminus (203S) results in an extremely unstable protein. This region of the protein may be essential in blocking degradation of pre-iron-sulfur protein by cytoplasmic proteases as the protein is imported into the mitochondria, or may be a "degradation signal," which tags the iron-sulfur protein for turnover.

Antimycin A↗
PubMed1989

Relationship between DNA-adduct formation, DNA repair, mutation frequency and mutation spectra.

DNA-adduct formation by a series of ethylating agents was determined and correlated with induction of gene mutations. This approach gave information concerning the DNA-adduct(s) likely to be responsible for the observed mutations. A methodology has been developed which is used for the DNA sequence analysis of point mutations in the HPRT gene of mammalian cells. This method can be used to obtain mutation spectra and to determine whether the base-pair changes do occur at those sites where DNA-adducts are likely to occur. Measurements of DNA repair in specific DNA sequences show that actively transcribed genes are repaired faster than the genome overall. This stresses the importance of studying removal DNA-adducts in the gene that is used for the analysis of mutation induction.

Animals↗
PubMed1989

Mutations of the ras protooncogenes in chronic myelogenous leukemia: a high frequency of ras mutations in bcr/abl rearrangement-negative chronic myelogenous leukemia.

Seventy cases of chronic myelogenous leukemia (CML) were analyzed for the presence of ras mutations using polymerase chain reaction (PCR), oligonucleotide hybridization, and direct PCR sequencing. All cases had preceding cytogenetic and bcr rearrangement studies. Aberrant ras genes were detected in none of 39 patients with Philadelphia (Ph) chromosome or bcr/abl rearrangement positive chronic-phase CML and in only 1 of 18 patients in blast crisis, suggesting that ras mutations have little or no role in initiation or progression of common CML. Seven of 13, or 54% of patients with bcr/abl rearrangement negative chronic phase CML (atypical CML) harbored mutations in ras, however. This high incidence of ras mutations, together with the absence of bcr/abl rearrangement, provides evidence that atypical CML is an entity that is molecularly distinct from common CML. Moreover, the clinical characteristics and the high frequency of ras mutations suggest that atypical CML may constitute a subset of the myelodysplastic syndrome and may be best classified as a variant of chronic myelomonocytic leukemia (CMML).

Base Sequence↗
PubMed1994

[Phenogenetic analysis of pigmentation of a new coat color mutation of American mink (Mustela vison. Schr. L.) and its combination with some of the known mutations].

A new dominant coat color mutation "talitsa" was revealed in the mink population of "Znamenskii" state fur farm (Tverskaya region', Russia). Qualitative analysis and quantitative assessment of the hair pigment of minks with the standard coat color, Talitsa, Royal-Pastel and American pearl mutations, as well as Talitsa x Royal-Pastel and Talitsa x American Pearl hybrids were conducted. It was shown that hair of all genotypes studied contained only one pigment type, namely, eumelanin. Hair of the standard-colored minks showed the greatest eumelanin content, whereas hair of Talitsa x Royal-Pastel and Talitsa x American Pearl hybrids showed the least content. The morphologic patterns of pigmentation of the mutant minks studied was described, including the shapes, dimensions and color of the pigment granules, as well as their distributions throughout the length and layers of the hair. Talitsa mutation was demonstrated to behave as a strong coloration attenuator in combinations with the Royal-Pastel and American Pearl mutations. It was proposed that the main mechanism determining the phenotypic expression of the Talitsa mutation is the reduction of number of melanocytes in the hair bulbs.

Animals↗
PubMed1996

Severe perinatal thrombosis in double and triple heterozygous offspring of a family segregating two independent protein S mutations and a protein C mutation.

Molecular genetic and phenotypic analyses were performed in a highly unusual case of combined protein S and protein C deficiency manifesting in a family in which a child had died perinatally from renal vein thrombosis. Antenatal diagnosis in a second pregnancy was initially performed by indirect restriction fragment length polymorphism (RFLP) tracking using a neutral dimorphism within the PROS gene and served to exclude severe protein S deficiency. Am umbilical vein blood sample at 22 weeks gestation showed isolated protein C deficiency. This pregnancy proceeded to a full-term delivery without thrombotic complications. Molecular genetic analysis of the PROC and PROS gene segregating in the family then yielded one PROC gene lesion in the father and two PROS gene lesions, one in each parent. These lesions were shown to segregate with the respective deficiency states through the family pedigree. Analysis of DNA from paraffin-embedded liver tissue taken from the deceased child showed the presence of both PROS mutations, as well as the PROC mutation. Genotypic analysis of the second child showed a PROC mutation, but neither PROS mutation consistent with its possession of normal protein S levels and a low/borderline protein C level. Antenatal diagnosis was then performed in a third pregnancy by direct mutation detection. However, although the fetus carried only the paternal PROS and PROC gene lesions, the child developed renal thrombosis in utero. It may be that a further genetic lesion at a third locus still remains to be defined. Alternatively, the intrauterine development of thrombosis in this infant could have been caused, at least in part by a transplacental thrombotic stimulus arising in the protein S-deficient maternal circulation. This analysis may, therefore, serve as a warning against extrapolating too readily from genotype to phenotype in families with a complex thrombotic disorder.

Female↗
PubMed1995

Infrequent somatic mutations of the p16 and p15 genes in human bladder cancer: p16 mutations occur only in low-grade and superficial bladder cancers.

A recently identified gene, p16, located on chromosome 9p21, has been shown to be deleted and/or mutated in various types of human cancers. To investigate structural alterations of p16 and a neighboring gene, p15, we examined human bladder cancers for mutations in the entire coding region of these genes using polymerase chain reaction and single-strand conformational polymorphism analysis. Of 50 samples obtained from patients with bladder cancer, 3 (6%), all low-grade and superficial tumors, were found to have p16 gene alterations. The alterations included 1 missense mutation and 2 single-base deletions. We found no p15 gene mutations in these 50 bladder cancers. Our results suggested that p16 gene mutations, although they occurred at low frequency, are involved in some low-grade and early stage bladder cancers.

Base Sequence↗