Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three gross rearrangements of the low density lipoprotein receptor (LDL-R) gene were recognized during a survey of 23 unrelated Italian subjects with familial hypercholesterolemia (FH). Restriction endonuclease data were obtained by Southern blotting and hybridization with exon-specific probes. Proband FH-29 is heterozygous for a 4-kb deletion, which eliminates exons 13 and 14. This mutation is similar to that previously reported by other investigators in one Italian homozygous and two British and Canadian heterozygous patients. Proband FH-30 is homozygous for a 5.5-kb insertion caused by a duplication of exons 16 and 17 of the LDL-R gene. LDL-R mRNA isolated from skin fibroblasts of FH-30 was found to be larger than normal mRNA (5.6 versus 5.3 kb), in concordance with the insertion of the 236 nucleotides corresponding to exons 16 and 17. Proband FH-44 was found to have greater than 25-kb deletion, which eliminates the first six exons and the promoter region of the gene. This is the first example of a deletion that eliminates the promoter as well as the ligand-binding domain of the LDL-R gene. In the skin fibroblasts of this patient, the level of LDL-R mRNA was approximately half that found in control fibroblasts. We designate the new mutations found in FH-30 and FH-44 as FHviterbo and FHBologna-1, respectively, after the names of the Italian cities where the two patients were born.
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PMID:Characterization of three mutations of the low density lipoprotein receptor gene in Italian patients with familial hypercholesterolemia. 199 42

We have recently identified a family of rhesus monkeys with members exhibiting a spontaneous hypercholesterolemia associated with a low density lipoprotein receptor (LDLR) deficiency. By using the polymerase chain reaction, we now show that the affected monkeys are heterozygous for a nonsense mutation in exon 6 of the LDLR gene. This mutation changes the sequence of the codon for amino acid 284 (tryptophan) from TGG to TAG, thereby generating a nonsense codon potentially resulting in a truncated 283-amino acid protein, which needs documentation, however. This G----A mutation also creates a site for the restriction endonuclease Spe I. Using this site as a marker for this nonsense mutation, we have shown that the mutation is present in all of the affected members of the pedigree and absent in unaffected members and that the mutation segregates with the phenotype of spontaneous hypercholesterolemia through three generations. Quantitative analyses of RNA obtained from liver biopsies show that the abundance of the LDLR RNA is also reduced by about 50%. Thus, we have identified a primate model for human familial hypercholesterolemia which will be useful for studying the relationship between the LDLR and lipoprotein metabolism and for assessing the efficacy of diets and drugs in the treatment of human familial hypercholesterolemia.
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PMID:Familial hypercholesterolemia in a rhesus monkey pedigree: molecular basis of low density lipoprotein receptor deficiency. 232 70

Haplotype analysis in 18 apparently unrelated families with familial hypercholesterolaemia (FH) in Iceland has identified at least five different chromosomes cosegregating with hypercholesterolaemia. The most common haplotype was identified in 11 of the 18 families, indicating a responsible for FH in the Icelandic population. By using single-strand conformation polymorphism (SSCP) and direct sequencing of amplified DNA, we identified a novel mutation (a T to a C) in the second nucleotide in the 5' part of intron 4 in the LDL receptor gene. This mutation was present in approximately 60% of the FH families (10/18), supporting the prediction of a common founder. These families could be traced to a common ancestor in half of the cases by going back no further than the eighteenth century. The mutation was predicted to affect correct splicing of exon 4, and analysis at the cellular level demonstrated an abnormal mRNA containing intron 4 sequence in lymphoblastoid cells from a patient carrying this mutation. Translation of the mRNA would lead to a premature stop codon and a truncated nonfunctional protein of 285 amino acids. The novel sequence change created a new restriction site for the restriction endonuclease NlaIII, and using this assay, 29 unrelated individuals with possible FH attending a lipid clinic for treatment were examined for this mutation. Two individuals in this group of patients were found to be carriers of this mutation, supporting the suggestion of a founder mutation. Using this assay for the detection of FH in the Icelandic population should identify > 60% of these individuals.
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PMID:Common founder mutation in the LDL receptor gene causing familial hypercholesterolaemia in the Icelandic population. 922 58

Familial hypercholesterolemia (FH) is an autosomal dominant disorder caused by mutations in the low density lipoprotein (LDL) receptor gene. Currently, diagnosis of heterozygous FH relies on clinical phenotype; however, the use of clinical criteria for the diagnosis of heterozygous FH does not always permit unequivocable diagnosis of the disease. Molecular diagnosis of FH is clinically valuable especially in regions where founder mutations exist or where polygenic hypercholesterolemia is prevalent. In this paper we report the identification of a novel mutation, a cytosine to guanine substitution, at codon 152 in exon 4 of the LDL receptor gene in a Nova Scotian family clinically diagnosed with heterozygous FH. The mutation creates a recognition sequence for the restriction endonuclease BsrI, and can be readily detected by BsrI restriction analysis of a 160 bp amplicon spanning the mutation. This analysis was used to show that the mutation segregated with the disease in this family and is the probable cause of FH in this kindred.
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PMID:A novel mutation in Exon 4 of the low density lipoprotein receptor gene resulting in heterozygous familial hypercholesterolemia associated with decreased ligand binding. 954 26

Several environmental and genetic factors are associated with high levels of cholesterol. Hypercholesterolemia is the main phenotype of Familial Defective Apolipoprotein B and Familial Hypercholesterolemia that are caused by mutations at the apolipoprotein (apo) B and LDL receptor genes, respectively. Identification of the specific genetic alteration associated with hypercholesterolemia is an important issue in clinical diagnosis of high risk for CAD. Apo B gene mutations and polymorphisms are usually screened by SSCP, DGGE, and heteroduplex, which must be confirmed by DNA sequencing or by direct detection using PCR techniques. In this study, we have optimized a PCR-RFLP procedure for identification of 3500Q and 3531 mutations and MspI polymorphism at the apo B gene. The technique can be performed in a single reaction, using the restriction endonuclease MspI for simultaneous detection of 3500Q mutation and MspI polymorphism, and NsiI for detection of 3531 mutation. The procedure was validated by analysis of control DNA samples from individuals carrying these mutations. Screening of 186 Brazilian hypercholesterolemic individuals showed that the frequency of the M-allele (7.8%) of MspI polymorphism was similar to that found in other individuals with CAD. However, neither 3500Q nor 3531 mutations were detected in this group. In conclusion, this procedure is simple and rapid, being easily introduced in clinical laboratories for direct detection of the more frequent mutations at the apo B gene associated with hypercholesterolemia.
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PMID:Rapid detection of 3500Q and 3531 mutations and MspI polymorphism in exon 26 at the apolipoprotein B gene. 1117 Feb 32

We employed the analysis of single-strand conformation polymorphisms to identify mutations in exon 4 of the low density lipoprotein receptor gene causing familial hypercholesterolemia. Three familial hypercholesterolemia heterozygotes had abnormal single-strand conformation polymorphism patterns. DNA sequencing revealed that the abnormal pattern of exon 4A was due to heterozygosity (T/C) at nucleotide 442. Nucleotide 442 is the first base of codon 127, and the T-->C mutation (C127R) changes this codon from CysTGT to ArgCGT. Abnormal patterns of exon 4B were due to heterozygosity (A/G) at nucleotide 662: nucleotide 662 is the second base of codon 200, and the A-->G mutation (D200G) changes this codon from AspGAC to GlyGGC. Mutation D200G was previously described as FH Padova, but mutation C127R (FH Zagreb) has not been reported previously. This novel mutation was confirmed by restriction endonuclease analysis with Dsa I. The screening of 420 familial hypercholesterolemia heterozygotes suggests that C127R and D200G account for about 0.7% of mutations causing familial hypercholesterolemia in Croatia.
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PMID:A novel missense mutation C127R (FH Zagreb) in the LDL-receptor gene. 1150 62

The ubiquity of mobile elements in mammalian genomes poses considerable challenges for the maintenance of genome integrity. The predisposition of mobile elements towards participation in genomic rearrangements is largely a consequence of their interspersed homologous nature. As tracts of nonallelic sequence homology, they have the potential to interact in a disruptive manner during both meiotic recombination and DNA repair processes, resulting in genomic alterations ranging from deletions and duplications to large-scale chromosomal rearrangements. Although the deleterious effects of transposable element (TE) insertion events have been extensively documented, it is arguably through post-insertion genomic instability that they pose the greatest hazard to their host genomes. Despite the periodic generation of important evolutionary innovations, genomic alterations involving TE sequences are far more frequently neutral or deleterious in nature. The potentially negative consequences of this instability are perhaps best illustrated by the >25 human genetic diseases that are attributable to TE-mediated rearrangements. Some of these rearrangements, such as those involving the MLL locus in leukemia and the LDL receptor in familial hypercholesterolemia, represent recurrent mutations that have independently arisen multiple times in human populations. While TE-instability has been a potent force in shaping eukaryotic genomes and a significant source of genetic disease, much concerning the mechanisms governing the frequency and variety of these events remains to be clarified. Here we survey the current state of knowledge regarding the mechanisms underlying mobile element-based genetic instability in mammals. Compared to simpler eukaryotic systems, mammalian cells appear to have several modifications to their DNA-repair ensemble that allow them to better cope with the large amount of interspersed homology that has been generated by TEs. In addition to the disruptive potential of nonallelic sequence homology, we also consider recent evidence suggesting that the endonuclease products of TEs may also play a key role in instigating mammalian genomic instability.
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PMID:Inviting instability: Transposable elements, double-strand breaks, and the maintenance of genome integrity. 1715 32

Transcription activator-like effector nucleases (TALENs) are programmable nucleases that join FokI endonuclease with the modular DNA-binding domain of TALEs. Although zinc-finger nucleases enable a variety of genome modifications, their application to genetic engineering of livestock has been slowed by technical limitations of embryo-injection, culture of primary cells, and difficulty in producing reliable reagents with a limited budget. In contrast, we found that TALENs could easily be manufactured and that over half (23/36, 64%) demonstrate high activity in primary cells. Cytoplasmic injections of TALEN mRNAs into livestock zygotes were capable of inducing gene KO in up to 75% of embryos analyzed, a portion of which harbored biallelic modification. We also developed a simple transposon coselection strategy for TALEN-mediated gene modification in primary fibroblasts that enabled both enrichment for modified cells and efficient isolation of modified colonies. Coselection after treatment with a single TALEN-pair enabled isolation of colonies with mono- and biallelic modification in up to 54% and 17% of colonies, respectively. Coselection after treatment with two TALEN-pairs directed against the same chromosome enabled the isolation of colonies harboring large chromosomal deletions and inversions (10% and 4% of colonies, respectively). TALEN-modified Ossabaw swine fetal fibroblasts were effective nuclear donors for cloning, resulting in the creation of miniature swine containing mono- and biallelic mutations of the LDL receptor gene as models of familial hypercholesterolemia. TALENs thus appear to represent a highly facile platform for the modification of livestock genomes for both biomedical and agricultural applications.
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PMID:Efficient TALEN-mediated gene knockout in livestock. 2302 55

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