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Results for “Genetic polymorphisms”

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At least 379 records · Page 21Linked to original sources
PubMed1985

Genetic polymorphism in drug oxidation: in vitro studies of human debrisoquine 4-hydroxylase and bufuralol 1'-hydroxylase activities.

A sensitive, specific assay utilizing fluorescence-HPLC has been developed for determining the 1'-hydroxylation of bufuralol by human liver. The 1'-hydroxylation of the isomers of bufuralol varied threefold, both the Vmax and the Km for the (+) isomer being greater than the corresponding values for the (-) isomer. Debrisoquine was a competitive inhibitor of the 1'-hydroxylation of both isomers and of the racemate of bufuralol. Both isomers and the racemate of bufuralol were competitive inhibitors of debrisoquine 4-hydroxylase activity. The competitive inhibition of debrisoquine and bufuralol of each other's metabolism, together with the similarity in the values for Km and Ki, support the conclusion that the same form of cytochrome P-450 catalyses these two reactions.

Cytochrome P-450 CYP2D6↗
PubMed1995

The molecular basis for genetic polymorphism of human deoxyribonuclease I: identification of the nucleotide substitution that generates the fourth allele.

In addition to the three alleles commonly responsible for the protein polymorphism of human deoxyribonuclease I, a mutation encoded by a fourth allele, DNASE1*4, was detected by isoelectric focusing. All 8 exons covering the entire open reading frame of the human DNase I gene were amplified by the polymerase chain reaction and subjected to direct sequencing. Only one nucleotide substitution, a C-to-G transition (CAG-->GAG), in the codon for amino acid 9 of the mature enzyme was found. This substitution resulted in the replacement of Gln with Glu (Q9E).

Alleles↗
PubMed1988

Aspartic proteinases in gastric mucosa of the rat: absence of pepsinogen I, genetic polymorphism of pepsinogen II, and presence of slow-moving proteinase.

We have examined relationships among the aspartic proteinases in rat and human gastric mucosa by electrophoretic analysis in polyacrylamide gel and by immunoblotting and immunohistochemical staining using rabbit antisera to human pepsinogen I (PG I), pepsinogen II (PG II), and slow-moving proteinase. By electrophoretic analysis, the major proteolytic bands in mucosal extracts from each of three strains of rats had rates of anodal migration that were similar to the fastest migrating isozymogens of human PG I. However, immunoblots revealed that these bands and several minor proteolytic bands with slower rates of anodal migration reacted with antiserum to PG II. Two proteolytic bands in rat gastric mucosa that migrated concurrently with human slow-moving proteinase reacted with antihuman slow-moving proteinase reacted with antihuman slow-moving proteinase. None of the proteolytic bands in rat gastric mucosa reacted with anti-PG I. By immunohistochemical staining, anti-PG I failed to stain any cells in rat fundic gland or antral mucosa. By contrast, anti-PG II stained mucus neck and chief cells in fundic gland mucosa and pyloric gland cells in antral mucosa, and anti-slow-moving proteinase stained surface and foveolar epithelial cells throughout the stomach. The results indicate that the gastric mucosa of the rat does not contain PG I.

Animals↗
PubMed1996

A novel single base deletion in the LDLR gene (211delG): Effect on serum lipid profiles and the influence of other genetic polymorphisms in the ACE, APOE and APOB genes.

A single base deletion (211delG) in the low density lipoprotein receptor (LDLR) gene was shown to cause familial hypercholesterolaemia (FH) in a large family from Northern Ireland. Twenty-four of 52 family members tested had this mutation, 13 of which were newly diagnosed. Mutation-positive individuals had significantly higher mean total-cholesterol (TC) and LDL-cholesterol (LDL-C) than those without 211delG. LDL-C was a more accurate indicator of disease status than TC. When TC levels alone were considered, in individuals over 16 years, a false negative rate (TC < 7.5 mmol/l) of 40% was found; however this fell to 13% based on inclusion of LDL-C levels. Individuals with coronary artery disease (CAD) had significantly higher TC levels than those without CAD and tended to have tendinous xanthomas (TX) and corneal arcus (CA). Generic polymorphisms in the angiotensin converting enzyme (ACE) and apolipoprotein (apo) B genes did not appear to be associated with lipid levels or with the clinical severity of the disease; however, the apo E epsilon4 allele did show a lipid-raising effect in individuals with the mutation.

Adolescent↗
PubMed1992

Phenotypic and genetic polymorphisms among human herpesvirus-6 isolates from North American infants.

Fifteen human herpesvirus-6 (HHV-6) isolates from North American infants with primary infection manifest as febrile or roseola (exanthem subitum) like illnesses were characterized phenotypically on the basis of their in vitro growth in continuous T-cell lines and primary human mononuclear cells and by their reactivity with monoclonal antibodies. All isolates replicated efficiently in primary human cord blood mononuclear cells, but five distinct patterns of viral replication in human cells lines were observed. Two of the HHV-6 isolates from infants were found to replicate in HSB-2 cells, a property associated with so-called group A viruses, which had previously been isolated only from adults. These same isolates also reacted with a panel of A-specific monoclonal antibodies. Genomic characterization of viral isolates using well-characterized restriction site polymorphisms indicated that these two isolates contained a mixture of both A- and B-type genomes, in different proportions. These data suggest that not all HHV-6 isolates can be categorized into one of two broad groups and that such segregation of HHV-6 isolates may in fact be misleading.

Cell Line↗
PubMed1995

Genetic polymorphism of the human tumor necrosis factor region in insulin-dependent diabetes mellitus. Linkage disequilibrium of TNFab microsatellite alleles with HLA haplotypes.

The TNF region within the MHC includes a number of immunologically important genes. Microsatellites TNFa and TNFb adjacent to TNF exhibit extensive polymorphism. Employing a PCR-based technique, we identified TNFab haplotypes and defined their distribution in 97 controls and 48 diabetics of Caucasoid origin in a search for other genes within the MHC potentially associated with IDDM. Twenty-five different TNFab haplotypes were identified. A significant difference (p < 0.0005) in frequency between patients and controls was found for TNFa1b5 (relative risk 53). However, no other TNFab microsatellites demonstrated significantly different frequencies. Among diabetics TNFa1b5 was found to be in linkage disequilibrium with HLA-DR3-B18, a haplotype known to be associated with IDDM. Thus the increased frequency of TNFa1b5 among diabetics could reflect a linkage disequilibrium with a gene within the TNF region or with other genes, including the HLAs, which characterize this haplotype. In both controls and diabetics TNFa2b3 and TNFa7b4 were in linkage disequilibrium with DR3-B8 and DR7, respectively. Among diabetics, TNFa2b1 and TNFa6b5 were in linkage disequilibrium with DR4-B62 and DR4-B44, respectively. It is intriguing that TNFab haplotypes, represented by a short piece of about 200 nucleotides in the untranslated region upstream of TNF beta gene, maintain strong linkage disequilibria with different HLA haplotypes extending over 1 million base pairs. The identification of TNFab microsatellites exhibiting a high polymorphic index in a region lacking known polymorphic markers may provide potentially important information regarding the association of HLA haplotypes with autoimmune diseases, as they are in close proximity to other genes of immunologic importance.

Alleles↗
PubMed1996

Genetic polymorphisms of the major histocompatibility complex-encoded antigen-processing genes TAP and LMP in sarcoidosis.

Sarcoidosis is a granulomatous disease showing a significant increase in the HLA-DR5, -DR6, and -DR8 associated alleles in Japanese. To investigate whether the class I antigen-processing genes, encoded within the MHC class II region between the HLA-DP and -DQ loci, are involved in determining the susceptibility to sarcoidosis, TAP1, TAP2, and LMP2 alleles were analyzed by the PCR-RFLP method in 85 Japanese patients with sarcoidosis and 91 healthy controls. There were no significant differences in the distribution of TAP1 and LMP2 alleles between the subgroups of the patients and controls positive or negative for DR5, DR6, and DR8. A significant decrease in the frequency of TAP2*0201 was found among the patients negative for DR5, DR6, and DR8 as compared to the DR-matched controls (p < 0.05), but this could be explained by its linkage disequilibrium to the negatively associated allele DR1. These findings suggest that the TAP or LMP2 gene is not primarily involved in the susceptibility to sarcoidosis. In the course of this study, a linkage disequilibrium was observed in the Japanese population between TAP1 and TAP2 alleles, TAP1*0201 and TAP2*0102.

ATP Binding Cassette Transporter, Subfamily B, Mem↗