PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Genetic Variation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,153 records · Page 64Linked to original sources
PubMed1972

Genetic variation in activity of enzymes involved in synthesis of catecholamines.

A genetic analysis of differences in adrenal phenylethanolamine N-methyltransferase (EC 2.1.1.X) and tyrosine hydroxylase (EC 1.99.1.X.) and brain tyrosine hydroxylase was performed in three inbred mouse strains. In adrenal glands, the pattern of inheritance of both enzymes was similar; genes carried by the CBA/J strain appeared to be dominant to those of the other strains. The pattern of inheritance of tyrosine hydroxylase activity in adrenals differed from that in the brain. In both tissues, dominant genes appeared to determine intermediate, rather than extreme, levels of enzyme activities.

Adrenal Glands↗
PubMedDate not supplied

Human microsatellites applicable for analysis of genetic variation in apes and Old World monkeys.

In studies of the genetics and social structure of primate populations there is a need to develop highly variable genetic markers for characterizing mating success and the nature of population movement or change through time. Because of their highly polymorphic nature, relatively simple amplification and typing, and the possibility of noninvasive sampling, microsatellites have become the molecular tool of choice in such studies. However, until recently it was assumed that many microsatellite loci, which are primarily situated in noncoding regions of the genome, evolve too rapidly to be applicable in evolutionarily divergent species. This has often resulted in the time-consuming process of cloning and sequencing microsatellites in new species. Here we describe the application of 11 human microsatellite primer pairs to a large group of primate species. The loci described are informative in all major groups of apes and Old World monkeys, although levels of allelic variability and heterozygosity differ across species. We confirm that with the use of appropriate universally applicable PCR conditions, a subset of human microsatellites are informative genetic markers in a wide range of divergent primate taxa.

Animals↗
PubMed1998

Genetic variation at the STR loci D12S391 and CSF1PO in four populations from Austria, Italy, Egypt and Yemen.

The short tandem repeat systems (STRs) D12S391 and CSF1P0 were amplified by the polymerase chain reaction (PCR) on blood samples from 100 to 158 unrelated Austrians, Italians, Yemenians and Egyptians. The samples were analyzed by both native and denaturing electrophoresis and two primer pairs were tested for the CSF1PO locus. Except for the CSF1PO data on the Egyptians, no deviations from the Hardy-Weinberg equilibrium were detected. For D12S391, no significant differences were found between the two Arab populations and between the two European populations, but the differences between both Arab populations and the Italians were significant. For CSF1PO, differences were only observed between the Yemenians and all three other populations. No evidence of linkage disequilibrium between the two STRs was found. The observation of a D12S391 allele consisting of only 14 repeats was confirmed by sequencing.

Alleles↗
PubMed1999

Genetic variation at nine STR loci in populations from the Philippines and Thailand living in Taiwan.

In order to apply a set of nine STR loci and the amelogenin locus in forensic testing, we have performed a population study on individuals from the Philippines and Thailand living in Taiwan (273 Philippine and 146 Thai individuals were typed by commercially available kits and an automated sequencer). A total of 73 alleles for all systems for both populations could be observed in these two populations. No new intermediate fragments were found. Allele frequencies showed no deviation from Hardy-Weinberg equilibrium. The mean exclusion power (MEP) ranged from 0.327 (TPOX) to 0.706 (FGA), the discriminating power (DP) ranged from 0.790 (TPOX) to 0.963 (FGA) for Philippinos, MEP ranged from 0.247 (TPOX) to 0.723 (FGA), DP ranged from 0.761 (TPOX) to 0.968 (FGA) for Thais, the combined MEP is > 0.9988 and the combined DP is > 0.9999999993 for both Philippinos and Thais.

Alleles↗
PubMed2002

Genetic variation across the historical range of the wild turkey (Meleagris gallopavo).

Genetic differences within and among naturally occurring populations of wild turkeys (Meleagris gallopavo) were characterized across five subspecies' historical ranges using amplified fragment length polymorphism (AFLP) analysis, microsatellite loci and mitochondrial control region sequencing. Current subspecific designations based on morphological traits were generally supported by these analyses, with the exception of the eastern (M. g. silvestris) and Florida (M. g. osceola) subspecies, which consistently formed a single unit. The Gould's subspecies was both the most genetically divergent and the least genetically diverse of the subspecies. These genetic patterns were consistent with current and historical patterns of habitat continuity. Merriam's populations showed a positive association between genetic and geographical distance, Rio Grande populations showed a weaker association and the eastern populations showed none, suggesting differing demographic forces at work in these subspecies. We recommend managing turkeys to maintain subspecies integrity, while recognizing the importance of maintaining regional population structure that may reflect important adaptive variation.

Animals↗
PubMed2005

Genomic medicine: genetic variation and its impact on the future of health care.

Advances in genome technology and other fruits of the Human Genome Project are playing a growing role in the delivery of health care. With the development of new technologies and opportunities for large-scale analysis of the genome, transcriptome, proteome and metabolome, the genome sciences are poised to have a profound impact on clinical medicine. Cancer prognostics will be among the first major test cases for a genomic medicine paradigm, given that all cancer is caused by genomic instability, and microarrays allow assessment of patients' entire expressed genomes. Analysis of breast cancer patients' expression patterns can already be highly correlated with recurrence risks. By integrating clinical data with gene expression profiles, imaging, metabolomic profiles and proteomic data, the prospect for developing truly individualized care becomes ever more real. Notwithstanding these promises, daunting challenges remain for genomic medicine. Success will require planning robust prospective trials, analysing health care economic and outcome data, assuaging insurance and privacy concerns, developing health delivery models that are commercially viable and scaling up to meet the needs of the whole population.

Delivery of Health Care↗
PubMed2006

Population level analysis of human immunodeficiency virus type 1 hypermutation and its relationship with APOBEC3G and vif genetic variation.

APOBEC3G and APOBEC3F restrict human immunodeficiency virus type 1 (HIV-1) replication in vitro through the induction of G-->A hypermutation; however, the relevance of this host antiviral strategy to clinical HIV-1 is currently not known. Here, we describe a population level analysis of HIV-1 hypermutation in [corrected] clade B proviral DNA sequences (n = 127). G-->A hypermutation conforming to expected APOBEC3G polynucleotide sequence preferences was inferred in 9.4% (n = 12) of the HIV-1 sequences, with a further 2.4% (n = 3) conforming to APOBEC3F, and was independently associated with reduced pretreatment viremia (reduction of 0.7 log(10) copies/ml; P = 0.001). Defective vif was strongly associated with HIV-1 hypermutation, with additional evidence for a contribution of vif amino acid polymorphism at residues important for APOBEC3G-vif interactions. A concurrent analysis of APOBEC3G polymorphism revealed this gene to be highly conserved at the amino acid level, although an intronic allele (6,892 C) was marginally associated with HIV-1 hypermutation. These data indicate that APOBEC3G-induced HIV-1 hypermutation represents a potent host antiviral factor in vivo and that the APOBEC3G-vif interaction may represent a valuable therapeutic target.

APOBEC-3G Deaminase↗
PubMed2006

Impact of a CART promoter genetic variation on plasma lipid profile in a general population.

The cocaine and amphetamine regulated transcript (CART), an anorexigenic peptide responding to leptin, is expressed in various areas of the hypothalamus. The role of CART in humans and its potential contribution to abnormalities in feeding control are mostly unknown. Since CART plays an important role in the hypothalamic regulation of energy balance by reducing food intake and increasing lipid substrate utilization, it might affect cholesterol metabolism as Neuropeptide Y or pro-opiomelanocortin do. In the present work, we studied the potential effects of three SNPs of the CART promoter in a WHO-MONICA general population from North of France (n=840), untreated for hypercholesterolemia, hypertension, or diabetes mellitus since any treatment is likely to interfere with lipoprotein/lipid variables. Our results show associations between these SNPs and plasma LDL-cholesterol level and the LDL/HDL ratio, a marker of atherogenicity. A haplotypic study suggests that these effects are mainly attributable to the functional SNP -3608C>T. Subjects bearing the -3608 C allele present a plasma lipid profile protective against atherogenesis: decrease of plasma LDL-cholesterol level (p=0.001) and of the LDL/HDL ratio (p=0.0003). This result offers new evidences for a potential implication of the CART gene in lipid metabolism and in atherogenesis.

Adult↗
PubMed1990

Spatial subdivision of populations and estimates of genetic variation.

Measures of variation in space are strongly affected by correlations between subdivisions used for sampling. Here we consider variation in gene frequencies across populations. Usually the variance of gene frequencies is standardized by dividing it by the mean gene frequency times one minus the mean (FST). Under the model of isolation by distance (usually called the "stepping stone" model), at the stationary state the correlation between the gene frequencies of two populations falls exponentially with the geographic distance between them. Using this model, we derive formulas for variances of blocks of populations of different sizes in one- and two-dimensional space and suggest that the theoretical results may be useful for understanding real observations, some examples of which are presented. We demonstrate how FST increases with the degree of subdivision among populations. We also show the effect of gaps between the sampled populations. Our results are valid, however, for traits other than gene frequencies, as long as their correlation with geographic distance falls exponentially. In the extension to 2-dimensional spaces, we present in closed form the distributions of distances between nodes of a lattice or of two lattices. These distributions might have applications in ecology.

Blood Group Antigens↗
PubMed2004

Population-based study of SR-BI genetic variation and lipid profile.

The variability of the Class B Type I Scavenger Receptor (SR-BI) gene in human populations and the relation of its variants to blood lipids was investigated in a random sample of 1756 untreated adult residents of Geneva, Switzerland, during 1999-2000. A three-step study approach yielded the following results: (1) resequencing the gene's exons and flanking regions in 95 subjects identified four common single nucleotide polymorphisms (SNPs with rare allele frequency >3%); (2) association study of the four common SNPs in subjects with extreme HDL-cholesterol (HDL-C) and LDL-C phenotypes (186 "atherogenic cases" and 185 "non-atherogenic controls") showed that the synonymous exon 8 C-T (allelic frequency 48%) polymorphism, A350A, was associated with atheroprotection in men (odds ratios (OR) = 0.36, 95% confidence intervals (CI) = 0.15-0.90, P < 0.03), but not in women (2.09, 0.79-5.49, P = 0.14); and (3) population clinical effects of A350A genotypes assessed in all 1756 subjects, showed that the case-control study findings reflected a protective HDL-C effect in men (CC: 1.17 mmol/L, CT: 1.22 mmol/L, and TT: 1.24 mmol/L, trend P = 0.0062) and a deleterious LDL-C effect in women (CC: 3.58 mmol/L, CT: 3.72 mmol/L, and TT: 3.79 mmol/L, trend P = 0.014). The allelic frequencies of the common SR-BI variants appear to be very similar in European and North American populations. The HDL-C effect increased with age. SR-BI A350A appears to have gender-specific and age-related effects on cholesterol transport lipoproteins.

Adult↗
PubMed2006

Genetic variation, population structure, and phylogenetic relationships of Triatoma rubida and T. recurva (Hemiptera: Reduviidae: Triatominae) from the Sonoran Desert, insect vectors of the Chagas' disease parasite Trypanosoma cruzi.

Nucleotide and amino acid sequence data from the mitochondrial cytochrome b (Cytb) and cytochrome c oxidase subunit I (COI) gene segments were used to gain insights into the population biology and phylogenetic relationships of two species of hematophagous kissing bugs (Hemiptera: Reduviidae: Triatominae) from the Sonoran Desert of northwestern Mexico and southern Arizona, USA, Triatoma rubida (Uhler, 1894) and T. recurva (Stål, 1868), both of which are vectors of the protozoan parasite Trypanosoma cruzi responsible for Chagas' disease. Analysis of molecular variance of gene sequences indicated significant structure among populations of both species from widely separated geographic localities. Phylogenetic analyses of gene and amino acid sequences employing both Bayesian and parsimony methods showed that T. recurva clustered within the phyllosoma complex of Triatoma species from central and southern Mexico with high statistical support, and that it was closely related to T. longipennis. Triatoma dimidiata also was shown to be closely related to the phyllosoma complex, as was T. sanguisuga which has historically been assigned to the lecticularia complex. Analyses of gene sequences were unable to confidently resolve relationships of T. rubida, although weak support for a T. nitida+T. rubida clade was seen under certain conditions. A provisional calibration of a mitochondrial DNA molecular clock for T. rubida, based on geological dates for the vicariant separation of the Baja California peninsula from mainland Mexico, suggested that pairwise sequence divergences for the Cytb and COI genes were 1.1-1.8% and 0.6-1.0% per million years, respectively. Two highly supported sympatric lineages of T. rubida uhleri from southern Arizona, which are hypothesized to have diverged approximately 550,000-900,000 years ago, were detected in the Cytb gene trees.

Amino Acid Sequence↗
PubMed1983

Genetic variation, chronic stress, and the central and peripheral noradrenergic systems.

Male rats from two inbred strains genetically selected for variation in response to stress were exposed for 9 consecutive days to 50 min of intermittent foot shock and killed 24 h after the last stress session. Maudsley Nonreactive (MNRA/Har) rats, genetically selected for decreased reactivity to stress, exhibited a significantly greater elevation (114% above control levels) in tyrosine hydroxylase activity in the locus ceruleus after chronic stress than Maudsley Reactive (MR/Har) animals (63% above control levels), genetically selected for heightened reactivity to stress. In the peripheral noradrenergic system, chronic stress produced an increase in norepinephrine (NE) content of small intestine and submaxillary gland of MNRA/Har rats, whereas chronic stress had no effect on NE content of these same tissues in MR/Har animals. These results are consistent with the proposition that genetic selection for variation in susceptibility to stress has altered the capacity of the central and peripheral noradrenergic system to adapt to chronic stress.

Adrenal Glands↗
PubMed2001

Antigenic variation among isolates of infectious salmon anaemia virus correlates with genetic variation of the viral haemagglutinin gene.

Infectious salmon anaemia virus (ISAV), an orthomyxovirus-like virus, is an important fish pathogen in marine aquaculture. Virus neutralization of 24 ISAV isolates in the TO cell line using rabbit antisera to the whole virus and comparative sequence analysis of their haemagglutinin (HA) genes have allowed elaboration on the variation of ISAV isolates. The 24 viruses were neutralized to varying degrees, revealing two major antigenic groups, one American and one European. Sequence analysis of the HA gene also revealed two groups of viruses (genotypes) that correlated with the antigenic groupings. The two HA subtypes had nucleotide sequence identity of only < or =79.4% and amino acid sequence identity of < or =84.5% whereas, within each subtype, the sequence identities were 90.7% or higher. This grouping was also evident upon phylogenetic analysis, which revealed two distinct phylogenetic families. Between the two groups, the amino acid sequence was most variable in the C-terminal region and included deletions of 4-16 amino acids in all isolates relative to ISAV isolate RPC/NB-980 280-2. In order to view the relationships among these sequences and the HA sequences of the established orthomyxoviruses, a second phylogenetic tree was constructed which showed the ISAV sequences to be more closely related to sequences from Influenzavirus A and Influenzavirus B than to sequences from Influenzavirus C and Thogotovirus. The extensive deletions in the gene of European ISAV isolates lead us to speculate that the archetypal ISAV was probably of Canadian origin.

Amino Acid Sequence↗
PubMedDate not supplied

Genetic variation and evidence of hybridization in the genus Rhus (Anacardiaceae).

Rhus michauxii, a rare plant species endemic to the southeastern United States, was previously known only from central North Carolina and one site in Georgia. An additional site, which is now believed to represent the largest known concentration of R. michauxii, was recently discovered at Ft. Pickett near Blackstone, Virginia. Morphological characteristics in several of the Ft. Pickett Rhus populations appear to be intermediate between R. michauxii and the widespread R. glabra, a closely related congener that co-occurs at Ft. Pickett. Although morphological evidence of hybridization between R. michauxii and R. glabra in North Carolina has been provided previously, genetic marker data are lacking. In the present study we examined levels of allozyme variation at 11 polymorphic loci within and among seven populations of R. michauxii, one population of R. glabra, and four putative hybrid populations at Ft. Pickett. Overall, R. michauxii had typical levels of within-population genetic variation when compared to other species with similar life-history characteristics. In contrast, the proportion of genetic variation among populations (G(ST)) was considerably lower than expected. Finally, R. michauxii and R. glabra appear to have a fixed allelic difference at the Idh2 locus. This enabled us to confirm hybridization in all four of the putative hybrid populations and one of the R. michauxii populations.

Genetic Variation↗
PubMed2004

Additive and nonadditive genetic variation in avian personality traits.

Individuals of all vertebrate species differ consistently in their reactions to mildly stressful challenges. These typical reactions, described as personalities or coping strategies, have a clear genetic basis, but the structure of their inheritance in natural populations is almost unknown. We carried out a quantitative genetic analysis of two personality traits (exploration and boldness) and the combination of these two traits (early exploratory behaviour). This study was carried out on the lines resulting from a two-directional artificial selection experiment on early exploratory behaviour (EEB) of great tits (Parus major) originating from a wild population. In analyses using the original lines, reciprocal F(1) and reciprocal first backcross generations, additive, dominance, maternal effects ands sex-dependent expression of exploration, boldness and EEB were estimated. Both additive and dominant genetic effects were important determinants of phenotypic variation in exploratory behaviour and boldness. However, no sex-dependent expression was observed in either of these personality traits. These results are discussed with respect to the maintenance of genetic variation in personality traits, and the expected genetic structure of other behavioural and life history traits in general.

Adaptation, Psychological↗
PubMed2001

Temporal patterns of genetic variation for resistance and infectivity in a Daphnia-microparasite system.

Theoretical studies have indicated that the population genetics of host-parasite interactions may be highly dynamic. with parasites perpetually adapting to common host genotypes and hosts evolving resistance to common parasite genotypes. The present study examined temporal variation in resistance of hosts and infectivity of parasites within three populations of Daphnia magna infected with the sterilizing bacterium Pasteuria ramosa. Parasite isolates and host clones were collected in each of two years (1997, 1998) from one population; in two other populations, hosts were collected from both years, but parasites from only the first year. We then performed infection experiments (separately for each population) that exposed hosts to parasites from the same year or made combinations involving hosts and parasites from different years. In two populations, patterns were consistent with the evolution of host resistance: either infectivity or the speed with which parasites sterilized hosts declined from 1997 to 1998. In another population, infectivity, virulence, and parasite spore production did not vary among host-year or parasite-year. For this population, we also detected strong within-population genetic variation for resistance. Thus, in this case, genetic variability for fitness-related traits apparently did not translate into evolutionary change. We discuss a number of reasons why genetic change may not occur as expected in parasite-host systems, including negative correlations between resistance and other traits, gene flow, or that the dynamic process itself may obscure the detection of gene frequency changes.

Animals↗
PubMed2002

[A study on genetic variation between wild and cultivated populations of Paeonia lactiflora Pall].

AIM: To discuss the genetic differentiation between wild and cultivated populations of Paeonia lactiflora Pall., and to find the reason for forming the genuineness of Radix Paeoniae rubra (Chishao) and Radix Paeoniae alba (Baishao). METHODS: Forty three representative samples of P. lactiflora from 11 localities were analyzed by RAPD method with 21 random primers. According to RAPD results, the genetic diversity and genetic differentiation of P. lactiflora were detected by the percentage of polymorphic sites (PPB), the coefficient of gene differentiation (GST) and analysis of molecular variance (AMOVA). RESULTS: (1) At species level, the PPB of P. lactiflora was 85.26%, the Nei's gene diversity (Ht) was 0.166. The PPB in wild population (WP) was 77.61%, which was more than that (54.96%) in cultivated population for medicine (MP), and that (61.76%) in cultivated population for ornament (OP). (2) AMOVA showed that 29.50% of the genetic diversity resulted from differentiation among populations. Pairwise Phist distance (0.3632) between WP and MP was furthest, while that (0.0973) between MP and OP was closest, indicating population differentiation was significant (P < 0.001). (3) In general, cluster analysis revealed that the samples of P. lactiflora were divided in wild and cultivated groups (except for 39). In WP, individuals of Duolun were separated from those of other localities. In MP, the clusters of samples corresponded well with their own habitats. CONCLUSION: In addition to environmental factor, genetic differentiation should be the main cause for the genuineness of "Chishao" and "Baishao". Because of over collection and worse habitat, P. lactiflora in Duolun, whose root is the famous Chinese Geo-herbal--"Duolun Chishao", is progresively rare. So, it should become the endangered germplasm resource to protect.

DNA, Plant↗