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At least 1,261 records · Page 70Linked to original sources
PubMed1997

Mutational analysis of the MPZ, PMP22 and Cx32 genes in patients of Spanish ancestry with Charcot-Marie-Tooth disease and hereditary neuropathy with liability to pressure palsies.

Charcot-Marie-Tooth disease (CMT) and hereditary neuropathy with liability to pressure palsies (HNPP) are two inherited peripheral neuropathies. The most prevalent mutations are a reciprocal 1.5-Mb duplication and 1.5-Mb deletion, respectively, at the CMT1A/HNPP locus on chromosome 17p11.2. Point mutations in the coding region of the myelin genes, peripheral myelin protein 22 (PMP22), myelin protein zero (MPZ) or connexin 32 (Cx32) have been reported in CMT patients, including CMT type 1 (CMT1), CMT type 2 (CMT2) and Déjérine-Sottas neuropathy (DS) patients, and only in the coding region of PMP22 in HNPP families lacking a deletion. We have investigated point and small mutations in the MPZ, PMP22 and Cx32 genes in a series of patients of Spanish ancestry: 47 CMT patients without duplications, and 5 HNPP patients without deletions. We found 15 different mutations in 16 CMT patients (34%). Nine different mutations in ten patients were detected in the Cx32 gene, this being the most frequently involved gene in this series, whereas five mutations involved the MPZ gene and only one the PMP22 gene. Six out of nine nucleotide substitutions in the Cx32 gene involved two codons encoding arginine at positions 164 and 183, suggesting that these two codons may constitute two Cx32 regions prone to mutate in the Spanish population. Analysis of HNPP patients revealed a 5' splicing mutation in intron 1 of the PMP22 gene in a family with autosomal dominance, which confirms allelic heterogeneity in HNPP. Ectopic mRNA analysis on leukocytes suggests that this mutation might behave as a null allele.

Charcot-Marie-Tooth Disease↗
PubMedDate not supplied

Base mutation analysis by a ferrocenyl naphthalene diimide derivative.

An electrochemical DNA sensing technique was developed by using ferrocenyl naphthalene diimide coupled with a probe DNA-immobilized electrode. This technique enabled detection of target DNA quickly and with high sensitivity. Applicability of this technique for single nucleotide polymorphisms (SNPs) analysis was demonstrated by successful analysis of a DNA mismatch on the cancer repression gene p53 with high precision.

DNA↗
PubMed2000

Escherichia coli promoter opening and -10 recognition: mutational analysis of sigma70.

The opening of specific segments of DNA is required for most types of genetic readout, including sigma70-dependent transcription. To learn how this occurs, a series of single point mutations were introduced into sigma70 region 2. These were assayed for duplex DNA binding, DNA opening and DNA double strand-single strand fork junction binding. Band shift assays for closed complex formation implicated a series of arginine and aromatic residues within a minimal 26 amino acid region. Permanganate assays implicated two additional aromatic residues in DNA opening, known to form a parallel stack of the type that can accept a flipped-out base. Substitution for either of these aromatics had no effect on duplex probe recognition. However, when a single unpaired -11 nucleotide is added to the probe, the mutants fail to bind appropriately to give heparin resistance. A model for DNA opening is presented in which duplex recognition by regions 2.3, 2.4 and 2.5 of sigma positions the pair of aromatic amino acids, which then create the fork junction required for stable opening.

Bacterial Proteins↗
PubMed1993

Mutational analysis of SRY in XY females.

The Y chromosome located gene SRY (sex determining region Y gene) was identified in the search for the mammalian testis determining factor (TDF). Approaches for evaluating SRY as a candidate for TDF included the finding of mutations in SRY in the genomes of patients with failed testis development (XY females or 46,XY gonadal dysgenesis) and the production of female to male sex reversed mice transgenic for the mouse homologue of SRY, [Sry]. Since the initial use of XY females in the proof of SRY/TDF identity, many more patients have been analysed using different techniques and more mutations identified. A total of 11 mutations in SRY have now been described, all in the DNA-binding HMG-box region of the gene, and all in patients with apparently complete gonadal dysgenesis. Surprisingly, three familial SRY mutations have been identified, where the phenotype is either fertile male or sterile sex-reversed female. Estimates of the proportion of XY females mutant for SRY average at approximately 15%. Reasons for the low frequency of SRY mutations in XY sex reversal could be the presence of mutations in regions of SRY not yet discovered, the occurrence of mutations that give the same phenotype, perhaps in genes close to SRY in the testis determining pathway, or incorrect diagnosis of complete gonadal dysgenesis.

Amino Acid Sequence↗
PubMed2000

Mutation analysis of exon 9 of the LDL receptor gene in Thai subjects with primary hypercholesterolemia.

The low density lipoprotein (LDL) receptor plays an important role in cholesterol homeostasis. A mutation in this gene causes an autosomal codominant disorder, namely familial hypercholesterolemia (FH). In this study, single strand conformation polymorphism (SSCP) analysis was used to screen for mutations in exon 9 of the LDL receptor gene in a group of 45 Thai patients (11 males and 34 females) with primary hypercholesterolemia. The peptide encoded by exon 9 belongs to the epidermal growth factor (EGF) precursor homology domain which is highly conserved in the LDL receptor protein. An abnormal SSCP pattern was observed in one female patient. The same screening strategy was also used to screen DNA samples from 33 normolipidemic subjects. All of these samples showed normal SSCP pattern. By direct DNA sequencing, the underlying mutation in the DNA with abnormal SSCP pattern was identified. The index subject was heterozygous for a T to C transition at nucleotide 1235. This transition would cause a nonconservative substitution of a nonpolar side chain amino acid "methionine" at codon 391, with an uncharged polar side chain amino acid "threonine", note M391T. From multiple amino acid sequence alignment in six species, the amino acid at codon 391 and the others nearby are completely conserved. Such nonconservative substitution of an amino acid residue in a highly conserved region could consequently result in a functional and/or structural defect in the receptor protein. In conclusion, we propose that M391T is likely to be the cause of hypercholesterolemia in this index subject.

DNA Mutational Analysis↗
PubMed1996

Mutational analysis of the p21/WAF1/CIP1/SDI1 coding region in human tumor cell lines.

p21/WAF1/CIP1/SDI1 is an important cell-cycle mediator with tumor suppressor gene capabilities, and its inactivation could potentially lead to tumor progression. Because tumor suppressor genes are commonly inactivated by somatic and germline mutations, we analyzed a variety of human tumor cell lines for p21 mutations. We used single-strand conformational analysis and direct sequencing to identify possible mutations in the p21 coding region. Two base-alterations were observed in 41 immortalized human tumor cell lines. A previously reported polymorphism that results in a serine-to-arginine amino-acid substitution at codon 31 was found in 24% (10 of 41) of the tumor cell lines but was also found in 10% (six of 62) of normal parental DNAs tested and 7% (three of 43) of normal DNAs from patients with primary endometrial tumors. Another nucleotide substitution found at codon 80 resulted in the replacement of threonine with methionine. Codon 80 changes were found in 7% (three of 41) of the tumor cell lines (all endometrial) and in 2% (one of 62) of the normal parental DNAs. This change was not found in any of the primary endometrial tumors examined. The biological activity of these base changes was analyzed by using in vitro cyclin-dependent kinase 2-cyclin A kinase assays and calcium phosphate transfections. We observed that wild-type p21 and the p21 variants had similar growth-inhibitory abilities. Thus, our results suggest that mutation of the p21 gene is not prevalent in human tumor cell lines and is not a probable mechanism of inactivation of this gene.

Base Sequence↗
PubMed2002

Immunohistochemistry of cyclin D1 and beta-catenin, and mutational analysis of exon 3 of beta-catenin gene in parathyroid adenomas.

Parathyroid adenomas are benign uniglandular tumors and are the most common cause of primary hyperparathyroidism. Several genetic changes in parathyroid tumors, including inactivation of tumor suppressor genes, activation of oncogenes and loss of heterozygosity at several chromosomal loci, have been reported. In this study, we analyzed the status of cyclin D1 and beta-catenin in 24 cases of parathyroid adenoma. Immunohistochemistry of cyclin D1 showed positive staining in 9 (37.5%) of the 24 parathyroid adenomas. The status of beta-catenin, which has recently been identified as a regulator of cyclin D1 transcription, was examined by direct sequencing of exon 3 of the beta-catenin gene and immunohistochemistry of beta-catenin protein, but neither mutation nor accumulation of beta-catenin was detected in any of the cases. These results indicate that cyclin D1 is frequently accumulated in parathyroid adenomas, independently of dysfunction in the Wnt signaling pathway.

Adenoma↗
PubMed2006

Mutational analysis of the ABCC6 gene and the proximal ABCC6 gene promoter in German patients with pseudoxanthoma elasticum (PXE).

Pseudoxanthoma elasticum (PXE) is a genetic disorder characterized by calcification of elastic fibers in dermal, ocular, and cardiovascular tissues. Recently, ABCC6 mutations were identified as causing PXE. In this follow-up study we report the investigation of 61 German PXE patients from 53 families, hitherto the largest cohort of German PXE patients screened for the complete ABCC6 gene. In addition, we characterized the proximal ABCC6 promoter of PXE patients according to mutation. In this study we identified 32 disease-causing ABCC6 variants, which had been described previously by us and others, and 10 novel mutations (eight missense mutations and two splice site alterations). The mutation detection rate among index patients was 87.7%. Frequent alterations were the PXE-mutations p.R1141X, Ex23,_Ex29del, and c.2787+1G > T. In the ABCC6 promoter we found the polymorphisms c.-127C > T, c.-132C > T, and c.-219A > C. The difference in the c.-219A > C frequencies between PXE patients and controls were determined as statistically significant. Interestingly, c.-219A > C is located in a transcriptional activator sequence of the ABCC6 promoter and occurred in a binding site for a transcriptional repressor, predominantly found in genes that participate in lipid metabolism. Obtaining these genetic data signifies our contribution to elucidating the pathogenetics of PXE.

Adolescent↗
PubMed2003

Functional map of human cytomegalovirus AD169 defined by global mutational analysis.

Human cytomegalovirus has a complex double-stranded DNA genome of approximately 240,000 bp that contains approximately 150 ORFs likely to encode proteins, most of whose functions are not well understood. We have used an infectious bacterial artificial chromosome to introduce 413 defined insertion and substitution mutations into the human cytomegalovirus AD169 genome by random and site-directed transposon mutagenesis. Mutations were produced in all unique ORFs with a high probability of encoding proteins for which mutants have not been previously documented and in many previously characterized ORFs. The growth of selected mutants was assayed in cultured human fibroblasts, and we now recognize 41 essential, 88 nonessential, and 27 augmenting ORFs. Most essential and augmenting genes are located in the central region, and nonessential genes generally cluster near the ends of the viral genome.

Cells, Cultured↗
PubMed2005

Mutation analysis of the ATM gene in two Chinese patients with ataxia telangiectasia.

Ataxia telangiectasia (A-T) is an autosomal recessive disorder characterized by cerebellar ataxia, telangiectasia, immunodeficiency, elevated alpha-fetoprotein level, chromosomal instability, predisposition to cancer, and radiation sensitivity. Although a lot of mutations in the ATM gene have been described, there is still no report about ATM mutations in Chinese population. Using a molecular approach, we screened for ATM mutations in two patients from two unrelated Chinese families. 100 normal controls were analyzed to exclude possibility of polymorphism. Two novel mutations in the ATM gene were identified. The first one is a novel, homozygous, 1346G>C (Gly449Ala) missense mutation. The second one is a compound heterozygous mutation, which consists of a novel, 610G>T (Gly204Stop) nonsense mutation, combined with a previously reported, 6679C>T (Arg2227Cys) missense mutation. The transversions 1346G>C (Gly449Ala) and 610G>T (Gly204Stop) are not localized either in the conserved PI-3 kinase domain or in the other domains of the ATM protein. The phenotypic features were characterized by progressive cerebellar ataxia, ocular telangiectasia, elevated alpha-fetoprotein level, immunodeficiency (agammaglo-bulinemia and T-cell defect), and rearrangements of chromosomes 7 and 14; brain MRI showed cerebellar atrophy, brain SPECT showed cerebellar regional cerebral blood flow (rCBF) hypoperfusion. To our knowledge, this is the first report of ATM mutations in Mainland China, in which the transversions 1346G>C (Gly449Ala) and 610G>T (Gly204Stop) are two novel, disease-causing mutations.

Adolescent↗
PubMed2004

Mutational analysis of mucopolysaccharidosis type VI patients undergoing a trial of enzyme replacement therapy.

Mucopolysaccharidosis type VI (MPS VI), or Maroteaux-Lamy syndrome, is a lysosomal storage disorder caused by a deficiency of N-acetylgalactosamine-4-sulfatase (ARSB). Seven MPS VI patients were chosen for the initial clinical trial of enzyme replacement therapy. Direct sequencing of genomic DNA from these patients was used to identify ARSB mutations. Each individual exon of the ARSB gene was amplified by PCR and subsequently sequenced. Nine substitutions (c.289C>T [p.Q97X], c.629A>G [p.Y210C], c.707T>C [p.L236P], c.936G>T [p.W312C], c.944G>A [p.R315Q], c.962T>C [p.L321P], c.979C>T [p.R327X], c.1151G>A [p.S384N], and c.1450A>G [p.R484G]), two deletions (c.356_358delTAC [p.Y86del] and c.427delG), and one intronic mutation (c.1336+2T>G) were identified. A total of 7 out of the 12 mutations identified were novel (p.Y86del, p.Q97X, p.W312C, p.R327X, c.427delG, p.R484G, and c.1336+2T>G). Two of these novel mutations (p.Y86del and p.W312C) were expressed in Chinese hamster ovary cells and analyzed for residual ARSB activity and mutant ARSB protein. The two common polymorphisms c.1072G>A [p.V358M] and c.1126G>A [p.V376M] were identified among the patients, along with the silent mutation c.1191A>G. Cultured fibroblast ARSB mutant protein and residual activity were determined for each patient, and, together with genotype information, were used to predict the expected clinical severity of each MPS VI patient.

Alternative Splicing↗