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)

Apolipoprotein E (apo E) is a polymorphic glycoprotein that plays an essential part in the binding to receptors for the uptake of chylomicrons and VLDL remnants and of LDL. The three major isoforms are E3 (Cys112/Arg158), E4 (Arg112/Arg158) and E2 (Cys112/Cys158). The apo E genetic variation has a great impact. In most of type III familial hyperlipoproteinemias (HLP), E2 is implicated at the homozygote status. In other cases, rare alleles are directly responsible for dominant type III HLP. Apo E polymorphism is an essential determinant in the interindividual variations of lipids in healthy subjects in various populations. Its influence can be significant on the efficacy of nutritional or therapeutic interventions. The allele epsilon 4 appears to be associated with an increased risk of premature atherosclerosis. Recently, epsilon 4 was demonstrated to be associated with an early Alzheimer's disease onset. Apo E polymorphism contributes to the lipid disorders in diabetes and obesity. The analysis of apo E polymorphism can be carried out with two conceptually different approaches. The first one is based on the separation of plasma isoforms of the protein by isoelectric focusing or bidimensional electrophoresis. The other one consists in the application of molecular biology techniques (PCR and endonuclease restriction profiles) for a detection of the common alleles and of several rare alleles, avoiding the possible errors of the phenotyping technique of the apo E protein. The application of genetic engineering allows a better understanding of the role played by apo E towards its receptors and in other molecular interactions which are not well known up to now.
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PMID:[Pathology of the human apolipoprotein E gene]. 807 81

We report a Canadian kindred with a novel mutation in the apolipoprotein (apo) A-I gene causing analphalipoproteinemia. The 34-yr-old proband, product of a consanguineous marriage, had bilateral retinopathy, bilateral cataracts, spinocerebellar ataxia, and tendon xanthomata. High density lipoprotein cholesterol (HDL-C) was < 0.1 mM and apoA-I was undetectable. Genomic DNA sequencing of the proband's apoA-I gene identified a nonsense mutation at codon [-2], which we designate as Q[-2]X. This mutation causes a loss of endonuclease digestion sites for both BbvI and Fnu4HI. Genotyping identified four additional homozygotes, four heterozygotes, and two unaffected subjects among the first-degree relatives. Q[-2]X homozygosity causes a selective failure to produce any portion of mature apoA-I, resulting in very low plasma level of HDL. Heterozygosity results in approximately half-normal apoA-I and HDL. Gradient gel electrophoresis and differential electroimmunodiffusion assay revealed that the HDL particles of the homozygotes had peak Stokes diameter of 7.9 nm and contained apoA-II without apoA-I (Lp-AII). Heterozygotes had an additional fraction of HDL3-like particles. Two of the proband's affected sisters had documented premature coronary heart disease. This kindred, the third reported apoA-I gene mutation causing isolated complete apoA-I deficiency, appears to be at significantly increased risk for atherosclerosis.
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PMID:Apolipoprotein A-I Q[-2]X causing isolated apolipoprotein A-I deficiency in a family with analphalipoproteinemia. 828 91

We report a rare apolipoprotein E variant in an Irish female with Type III hyperlipidaemia who has the phenotype E2E1 as determined by isoelectric focusing. Sequence analysis of the apolipoprotein E gene from the proband and from four other family members, using DNA amplified by the polymerase chain reaction, demonstrated the presence of a point mutation in the common epsilon 2 allele with a G-->A transition at nucleotide 3791. This was confirmed by digestion with the restriction endonuclease TaqI, which cuts at a new site within the apolipoprotein E gene, created by the base change. This mutation results in a substitution of aspartic acid for glycine at position 127 of the mature protein. We believe this to be the first description of this apolipoprotein E variant in a family from the British Isles. The mutation appears to be 'recessive' with respect to the expression of Type III hyperlipidaemia, although it may be somewhat more potent in this regard than the parent epsilon 2 allele. The Type III hyperlipidaemia is responsive to treatment with diet and gemfibrozil.
Atherosclerosis 1993 Mar
PMID:Rare apolipoprotein E variant identified in a patient with type III hyperlipidaemia. 850 53

In the process of screening apolipoprotein (apo) E genotypes in a population of subjects with lipid abnormalities, we have identified five subjects (one homozygote and four heterozygotes) with an abnormal 109 base pairs band following apo E restriction isotyping of amplified DNA with the restriction endonuclease CfoI. The polymerase chain reaction (PCR) products were cloned and their sequencing revealed a C-->A substitution at the first nucleotide of codon 136. This mutation resulted in an amino acid substitution Arg to Ser, previously described as apo E2 Christchurch. Family studies were carried out for four of the probands. In these kindreds, stepwise multiple regression analyses indicated that 78% of the cholesterol variability in men was predicted by body mass index, age and the rare apo E2 (Arg136-->Ser) variant. In women, age and the apo E2 (Arg136-->Ser variant predicted 54.9% of the variability in cholesterol levels. Linkage analysis suggested that the presence of the apo E2 (Arg136-->Ser) variant was linked with the occurrence of cholesterol enriched triglyceride rich lipoproteins and with an incomplete dominance of type III hyperlipoproteinemia. Our data indicates that this mutation may be a relatively common cause of dyslipidemia in the Spanish population.
Atherosclerosis 1996 Apr 26
PMID:Incomplete dominance of type III hyperlipoproteinemia is associated with the rare apolipoprotein E2 (Arg136-->Ser) variant in multigenerational pedigree studies. 872 10

The development of atherosclerotic plaques is characterised by the accumulation of lipids and the proliferation of smooth muscle cells. At the subcellular level, the abnormal expression of cytokines and growth factors, as well as the presence of transforming oncogenes, has been recognised and associated with the disease. The aim of the present study was to investigate whether instability at a minisatellite region located downstream of the H-ras proto-oncogene possessing enhancer activity, is a detectable phenomenon in atherosclerotic plaques. Thirty specimens were analysed by polymerase chain reaction (PCR) in order to reveal alterations of the repetition number and by restriction fragment length polymorphism (RFLP) with BstNI restriction endonuclease for the detection of point mutations within the 28 bp core repetitive element. No point mutations were found among the 30 cases tested; however, alterations of the repetition number of the core were detected in 5 (17%) cases. Our results suggest that instability at the H-ras minisatellite may be associated with development of the disease.
Atherosclerosis 1996 Aug 23
PMID:Instability at the H-ras minisatellite in human atherosclerotic plaques. 883 26

A 49 year-old hypercholesterolemic male with marked electrocardiographic ST segment depression on exercise testing was found to have an apo E E3/3 phenotype by isoelectric focusing, but an APOE E4/3 genotype using HhaI restriction isotyping. DNA sequence analysis of the proband's APOE gene found a G-->C point mutation at codon 251. This predicted a change in the amino acid encoded by codon 251, from arginine to glycine. The mutation occurred on an allele that encoded arginine at position 112 and this variant was named APOE R112; R251G. The R251G change altered a recognition site for the endonuclease StuI and was the basis for a restriction isotyping method to rapidly screen for this mutation. In relatives of the proband, APOE R112; R251G was consistently found in subjects with both hyperlipidemia and atherosclerosis. Apo E R112; R251G-containing very low density lipoproteins bound normally to macrophages in vitro. However, the proband had an abnormal post-prandial lipoprotein response to a dietary fat challenge. The association of APOE R112; R251G with abnormal phenotypes suggests that the amino acid change in the carboxy-terminal, perhaps in combination with the common amino acid polymorphism at codon 112, has a functional impact upon lipoprotein metabolism in members of this family.
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PMID:Apolipoprotein E R112; R251G: a carboxy-terminal variant found in patients with hyperlipidemia and coronary heart disease. 936 Jun 38

Familial hypobetalipoproteinemia is an autosomal co-dominant disorder, which in a minority of cases is due to a truncation producing mutation in the apoB gene. We have identified an apoB mutation in a 40-year old hypobetalipoproteinemic man with Type II diabetes mellitus. Immunoblotting of plasma revealed a major band for apoB-100 and a minor band with estimated size between apoB-52 and apoB-55. The proband's 75-year old father with Type II diabetes and a non-diabetic daughter also possessed the truncated protein. Direct sequencing of the amplified fragment of genomic DNA revealed a C-->T transition at nt 7692 in exon 26 of the apoB gene. This substitution yielded a premature stop codon at residue 2495 and abolished a BsaI restriction endonuclease site. The identical mutation has been described previously; however, the genotypes and ancestors of the kindred were different, suggesting that the mutation may have occurred independently. The majority of apoB-55 was eluted as particles smaller than LDL-sized apoB-100, and floated mostly between the LDL and HDL density range. It is worth noting that despite the presence of Type II diabetes, both the proband and his father have very low plasma lipid levels and neither have any clinically manifest macrovascular complications.
Atherosclerosis 1998 Feb
PMID:Diabetes mellitus in a new kindred with familial hypobetalipoproteinemia and an apolipoprotein B truncation (apoB-55). 954

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.
Atherosclerosis 1998 Jan
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

We found a novel G-->A change at nucleotide -25 within the promoter of the CTSS gene encoding the elastase cathepsin S. The CTSS -25G/A polymorphism could be detected by digestion with endonuclease BfmI. The frequency of the CTSS -25A allele was 0.457 in Caucasians and 0.431 in Canadian Inuit. Because of the importance of the CTSS gene product in vascular matrix remodeling, this polymorphism may be useful in the study of associations with atherosclerosis and related phenotypes.
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PMID:Human cathepsin S gene (CTSS) promoter -25G/A polymorphism. 1072 71

We found a novel G-->C change at nucleotide 1059 within exon 2 of the CRP gene encoding the C-reactive protein. The CRP 1059G/C polymorphism could be detected by digestion with endonuclease MaeIII. The frequency of the CRP 1059C allele was 0.109 in Caucasians, but it was absent from Canadian Oji-Cree. Because of the importance of the CRP gene product in inflammation and its recent association with ischemic heart disease syndromes, this polymorphism may be useful in the association studies of atherosclerosis and its related phenotypes.
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PMID:Human C-reactive protein (CRP) 1059G/C polymorphism. 1072 74


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