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 1,441 records · Page 80Linked to original sources
PubMed2025

Human genetic variation reveals FCRL3 is a lymphocyte receptor for Yersinia pestis.

Yersinia pestis is the bacterium responsible for plague, one of the deadliest diseases in history. To discover human genetic determinants of Y. pestis infection, we utilized nearly 1,000 genetically diverse lymphoblastoid cell lines in a cellular genome-wide association study. A nonsynonymous SNP, rs2282284 (N721S), in Fc receptor-like 3 (FCRL3) was associated with bacterial invasion of host cells (p = 9 × 10-8). Overexpressed FCRL3 facilitated attachment and invasion of Y. pestis and colocalized with Y. pestis at attachment sites. These properties were variably conserved across the FCRL family, revealing an immunoglobulin-like domain and signaling motifs shared by FCRL3 and FCRL5 to be necessary for attachment and invasion. Direct binding to FCRL5 extracellular domain was confirmed, and B cells (the primary cells that express FCRLs) were preferentially invaded by Y. pestis. Thus, Y. pestis hijacks FCRL proteins, possibly taking advantage of an immune receptor to create a lymphocyte niche during infection.

Yersinia pestis↗
PubMed1998

Regional genetic variation in Caucasians.

When evaluating DNA evidence, the necessary calculations are often carried out using databases drawn from broad populations; for example, the Forensic Science Service (FSS) maintains genetic databases for the 3 major racial groups of England and Wales--Caucasian, Afro-Caribbean and Asian (from the Indian subcontinent). The resulting figures may be challenged in court on the premise that they are not based on data from the population of most relevance in the particular case under consideration. One important factor might be the location of the crime. Since the recent establishment of a National DNA Intelligence Database, data have been made available from a wide range of geographical regions in England and Wales. This paper gives details of analyses conducted to measure the differentiation between white caucasian populations from these regions and from other areas of the UK and abroad using a Bayesian approach.

Bayes Theorem↗
PubMed2006

Genetic variation of porcine prostaglandin-endoperoxide synthase 2 (PTGS2) gene and its association with reproductive traits in an Erhualian x Duroc F2 population.

Identification of major genes that genetically impact female fertility is important for successful selection of high prolificacy pig lines. Because it is the rate-limiting enzyme in the conversion of arachidonic acid to prostaglandins (PGs), which are important for ovulation, fertilization, implantation, decidualization and parturition, prostaglandin-endoperoxide synthase 2 gene (PTGS2) is a potential candidate gene affecting porcine reproductive traits. In this study, a PCR-RFLP was used to genotype a total of 1 031 animals, including 661 from twelve Chinese local pig breeds, 190 from three Western pig breeds and 180 F2 sows from Nanchang pig resource family. Differences in frequency distributions of PTGS2 among twelve Chinese and three Western pig breeds and populations generally agree with their prolificacy. The allele frequencies in Lower Changjiang River Basin Type pig breeds, North China Type and Central China Type breeds are significantly different from those in South China Type, Plateau Type and Western pig breeds (P<0.001). And no significant differences were observed among Lower Changjiang River Basin Type, North China Type, Central China Type pig breeds, between South China Type and Western pig breeds, in part because of similar fertility patterns. And notable associations as well as reliable additive and dominant effects were not detected in an Erhualian x Duroc F2 population (P>0.05). Whereas, there is a trend for animals with one copy of the favourable A allele to have an increased TNB (total number of piglet born) and TBA (the number of piglets born alive) and a decreased SB (stillborn pigs) trait. Considering its crucial role in reproductive pathways, the PTGS2 gene deserves further study.

Animals↗
PubMed2006

Influence of genetic variation in the C-reactive protein gene on the inflammatory response during and after acute coronary ischemia.

The aim of this research was to assess whether common genetic variants within the C-reactive protein gene (CRP) are related to the degree of acute rise in plasma C-reactive protein (CRP) levels following an acute coronary syndrome (ACS). While polymorphisms within CRP are associated with basal CRP levels in healthy men and women, less is known about the relationship of such genetic variants and the degree of CRP rise during and after acute ischemia. Plasma CRP is associated with increased rates of recurrent coronary events. We evaluated seven common genetic variants within CRP and assessed their relationship to the degree of rise in CRP levels immediately following an acute coronary syndrome in 1827 European American patients. Variants in the putative promoter region, -757T > C and -286C > T > A, were associated with the highest CRP elevations after ACS. Patients with two copies of the A allele of SNP -286C > T > A had median CRP values of 76.6 mg/L, compared to 11.1 mg/L in patients with no copies of the rare variant (p-value <0.0001), post ACS. The lowest CRP values were found for patients with minor alleles of the exonic 1059G > C and the 3'untranslated region 1846G > A SNPs. For example, patients homozygous for the minor allele of 1059G > C had 71% lower median CRP values than those homozygous for the major allele [3.5 vs 12.0 mg/L, p < 0.0001]. These trends persisted in the chronic stable phase after ischemia had resolved, and after adjustment for infarct size by peak creatinine kinase levels and clinical status by Killip class. Assessment of CRP genetic variants identified patients with higher and lower CRP elevation after acute coronary syndrome.

Acute Disease↗
PubMed2002

Genetic variation within the premembrane coding region of dengue viruses from the Yucatan peninsula of Mexico.

Single-strand conformation polymorphism (SSCP) and sequence analyses were used to characterize genetic polymorphisms and phylogenetic relationships, respectively, among dengue (DEN) viruses isolated between 1980 and 1997 from Yucatan, Mexico and surrounding states. Amplified cDNAs from the premembrane (prM) coding region of the DEN viruses were characterized by SSCP. There were six distinct haplotypes of DEN-1 viruses, four haplotypes of DEN-2, four haplotypes of DEN-3, and eight haplotypes of DEN-4. The diversity index for DEN-3 isolates was significantly lower than that of the other serotypes, probably reflecting the recent introduction of this viral serotype into Mexico. The SSCP was a sensitive (84.5%) and specific (95.5%) technique for identifying nucleotide substitutions. Sequence analyses provided insight into the phylogenetic relationships of the DEN strains isolated in Yucatan. One DEN-2 isolate from 1996 was demonstrated to cluster with viruses of the Sri Lanka genotype, none of which have been detected before in the Americas.

Base Sequence↗
PubMed2003

[Genetic variations and possible therapeutic ways of male infertility].

Chromosome aberrant and some gene mutations play an important role in male infertility. A knowledge of a variety of new genetic causes is crucial for the prevention and treatment of male infertility. This review focused on known genetic causes of male infertility, male fertility-related candidate genes from knockout mice, genetic analysis and treatment of infertility in men.

Animals↗
PubMed1976

Genetic variation in heterogeneous environments.

A model of population structure in heterogeneous environments is described and conditions sufficient for maintaining a polymorphism are derived. The absolute fitness of any genotype is regarded as a function of location in the niche space and the population density at that location. Two modes of habitat selection are examined: (1) organisms are distributed uniformly over the environment; and (2) each organism selects to occupy that habitat in which it is most fit ("optimal habitant selection"). Sufficient conditions for maintenance of genetic polymorphisms are derived for both models. In populations which do not practice habitat selection heterozygote superiority averaged over the environment is sufficient to guarantee the existence of polymorphisms. Comparable conditions for populations which practice optimal habitat selction are much less restrictive. If the heterozygotes are superior to one homozygote in any one part of the niche and to the other homozygote in any other part of the niche then a polymorphism will be defined. A positive correlation between genetic and environmental variation follows from the model with habitat selection, but not from the other. The adaptive significance of polymorphisms thus depends on how animals behave.

Environment↗
PubMed2004

Gender specific association of genetic variation in peroxisome proliferator-activated receptor (PPAR)gamma-2 with longevity.

Long-lived subjects have been shown to have peculiar anthropometric features (i.e. lower body mass index (BMI)) and metabolic parameters (i.e. improved insulin sensitivity). Life style and a genetic background potentially protective against the age-related metabolic derangement might contribute to such a particular phenotype. Peroxisome proliferator-activated receptor (PPAR)gamma-2 is an important regulator of adipose tissue metabolism, insulin sensitivity and inflammatory response. Thus, the potential role of genetic variability at Pro/Ala loci of PPARG gene on longevity was studied in 222 long-lived subjects and 250 aged subjects. We found a different Pro/Ala genotype frequency distribution between long-lived and aged men subjects, long-lived men having an increased frequency of Pro/Ala genotype (20 vs 8.5%); no differences was found when allele and genotype distribution of Pro/Ala gene polymorphism were analyzed in the two age group of women. Interestingly, subjects with Pro/Ala polymorphism had significantly lower BMI than Ala/Ala and Pro/Pro polymorphism. In conclusion, our study demonstrated that paraoxonase Pro/Ala gene polyporphism is associated with human longevity. Such an effect is probably due to the effect of Pro/Ala polymorphism on body composition and appears to be gender specific.

Adult↗
PubMed2001

[Influence of genetic variation in the major histocompatibility complex on head and neck cancer susceptibility].

BACKGROUND: While cigarette smoking and alcohol consumption are risk factors for squamous cell carcinomas (SCC) of the head and neck, genetic factors are also significant. The gene of tumor necrosis factor (TNF) is located in the major histocompatibility complex class III and the cytokine has pleiotropic actions some of which are anticarcinogenic. As this gene complex is polymorphic with microsatellite markers identified it is a further candidate for head and neck cancer susceptibility. METHODS: We used a case-control approach to study the influence of polymorphism at the A-D markers on susceptibility in 113 controls, 265 laryngeal and 123 oral cavity/pharyngeal SCC cases. Genotypes were identified on polyacrylamide gels in an automated DNA sequencer after amplification with fluorescently-labeled primers. RESULTS: We found no differences in allele frequencies between controls and oral cavity/pharyngeal SCC cases but the frequency of B3 was greater in the laryngeal SCC cases than controls (p = 0.004, odds ratio 2.8). Homozygosity for B3 conferred an increased risk of laryngeal cancer compared with controls (p = 0.021, odds ratio 10.8). CONCLUSIONS: The data provide the first evidence that allelism at MHC class III microsatellite markers is associated with risk to laryngeal SCC.

Aged↗
PubMed1990

Genetic variation and origin of the most chromosomally polymorphic natural mammalian population.

Examination of allozymic variation in a chromosomally highly polymorphic population of Oryzomys documented that the sample consisted of two species, one that was chromosomally monomorphic and the other containing nine centric fusion polymorphisms. The existence of allozymic variation indicates that it is highly improbable that the polymorphic sample was the result of hybridization. These centric fusion polymorphisms appeared to cause little or no negative selection.

Alleles↗
PubMedDate not supplied

Genetic variation at three VNTR loci in three tribal populations of Orissa, India.

BACKGROUND: The variable number of tandem repeats (VNTR) loci are robust, simple and rapid tools for genetic characterization of both individuals and populations. This paper presents data on the distribution of three VNTRs (APOB, YNZ22 and D1S80) in three tribal populations (Gadaba, Kuvi-Khond and Paroja) of the Koraput district of Orissa, India with a view to enlarge our understanding of molecular genetic diversity among these tribes and the usage of these VNTRs in anthropogenetic studies. SUBJECTS AND METHODS: Three tribal populations were genotyped for APOB, YNZ22 and D1S80 loci using the polymerase chain reaction (PCR) technique. Gadaba are an Austro-Asiatic tribe while Kuvi-Khond and Paroja are Dravidian tribes. All samples were collected, with consent, from unrelated individuals. RESULTS: The observed allelic variation in these tribes is comparable with many Indian populations, but they showed significant overall and inter-population variability within the region. Allele *24 was the most common allele at the D1S80 locus in all populations, with Gadabas having the highest frequency (50%) followed by Paroja (32%) and Kuvi-Khond (23%). Gadabas also showed a higher frequency of allele *19 (13%) and *31 (9%) compared to other Indian and European populations. In the Apo B system, allele *37 was the most common in all three populations, with Gadabas having the highest frequency (39%) followed by Paroja (24%) and Kuvi-Khond (21%). This allele is present in high frequencies in other Indian (except Gonds) and European populations. Alleles *33 (17%), *35 (20%) and *45 (12%) were also common in the Gadabas, but Kuvi-Khond showed higher frequencies of *31(10%), *35(13%) and the larger allele *49(16%). Paroja, on the other hand, had higher frequencies of *31 (14%), *33 (17%) and *45 (13%). Allele *49 was also present in Paroja (10%) but was absent in the Gadaba. For the YNZ22 system, allele *4 was the most common in Kuvi-Khond (25%) and Paroja (21.4%), and allele *2 was the predominant allele in the Gadaba (33%). However allele *4 still occurs at relatively high frequency in Gadaba (27%). Allele *2 also occurs at relatively high frequency in Kuvi-Khond (20%) and intermediate frequency in Paroja (11%). Average heterozygosity was relatively low for Gadaba (0.7597 +/- 0.0191) and high for Kuvi-Khond (0.8618 +/- 0.0149) and Paroja (0.8512 +/- 0.0190), perhaps a reflection of effective population size and limitations to mating. The level of gene differentiation is, however, low (3-4%) for the three systems studied in these tribal populations and in data compiled from previous studies from the region. CONCLUSIONS: The VNTRs are polymorphic in the tribal populations studied and there is extensive allelic variation. Gadabas are isolated but Kuvi-Khond and Paroja show clear affinities with the Gonds, a major tribal group of Central India. Overall, allele frequency distribution, heterozygosity and genetic diversity analysis show that genetic diversity observed is socially, linguistically and geographically structured in this region.

Alleles↗
PubMed1993

Genetic variation among the Mapuche Indians from the Patagonian region of Argentina: mitochondrial DNA sequence variation and allele frequencies of several nuclear genes.

DNA samples from 60 Mapuche Indians, representing 39 maternal lineages, were genetically characterized for (1) nucleotide sequences of the mtDNA control region; (2) presence or absence of a nine base duplication in mtDNA region V; (3) HLA loci DRB1 and DQA1; (4) variation at three nuclear genes with short tandem repeats; and (5) variation at the polymorphic marker D2S44. The genetic profile of the Mapuche population was compared to other Amerinds and to worldwide populations. Two highly polymorphic portions of the mtDNA control region, comprising 650 nucleotides, were amplified by the polymerase chain reaction (PCR) and directly sequenced. The 39 maternal lineages were defined by two or three generation families identified by the Mapuches. These 39 lineages included 19 different mtDNA sequences that could be grouped into four classes. The same classes of sequences appear in other Amerinds from North, Central, and South American populations separated by thousands of miles, suggesting that the origin of the mtDNA patterns predates the migration to the Americas. The mtDNA sequence similarity between Amerind populations suggests that the migration throughout the Americas occurred rapidly relative to the mtDNA mutation rate. HLA DRB1 alleles 1602 and 1402 were frequent among the Mapuches. These alleles also occur at high frequency among other Amerinds in North and South America, but not among Spanish, Chinese or African-American populations. The high frequency of these alleles throughout the Americas, and their specificity to the Americas, supports the hypothesis that Mapuches and other Amerind groups are closely related.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1992

Genetic variation at enzyme loci in North Atlantic minke whales, Balaenoptera acutorostrata.

Electrophoretic variation within and between North Atlantic minke whale samples (Balaenoptera acutorostrata) from West Greenland, Iceland, and Norway was investigated. In the West Greenland samples, 28 enzyme systems were examined, representing 36 loci, of which 6 were found to be polymorphic. In Icelandic and Norwegian samples, 22 enzyme systems were examined, representing 29 loci, of which 6 and 5 were found to be polymorphic, respectively. The average heterozygosity was 0.058 (SE = 0.024) in samples from West Greenland, 0.074 (SE = 0.028) in samples from Iceland, and 0.054 (SE = 0.023) in samples from Norway. No significant deviations from the expected Hardy-Weinberg genotypic frequencies, within samples taken from the same area, were found. Significant differences in allele frequencies were observed, however, between samples from the three different areas. The average Nei's genetic distance was 0.014 and the average Fst value was 0.126. The genetic differences between the samples from the different areas indicate that those from West Greenland, Iceland, and Norway represented different breeding populations.

Alleles↗
PubMed2002

Nuclear and mitochondrial genetic variation in the Yanomamö: a test case for ancient DNA studies of prehistoric populations.

Ancient DNA provides a potentially revolutionary way to study biological relationships in prehistoric populations, but genetic patterns are complex and require careful interpretation based on robust, well-tested models. In this study, nuclear and mitochondrial markers were compared in the Yanomamö, to assess how well each data set could differentiate among closely related groups. The villages selected for the study share a recent fission history and are closely related to each other, as would likely be the case among prehistoric peoples living in the same valley or region. The Yanomamö generally practice village-level endogamy, but some migration and gene flow are known to occur between villages. Nuclear and mitochondrial DNA data were compared using F-statistics and genetic distance analyses. The nuclear data performed as expected, males and females from the same village were similar, and the villages were genetically distinct, with the magnitude of genetic differences correlated with historical relationship. However, mtDNA analyses did not yield the expected results. The genetic distances between villages did not correlate with historical relationship, and the sexes were significantly different from each other in two villages. Both the Lane and Sublett and the Spence methods, used to test for archaeological residence patterns, were consistent with endogamy. Hence, ancient DNA can, in principle, provide us with a unique opportunity to study genetic structure and gene flow in archaeological populations. However, interpretations, particularly those based on single loci such as mitochondrial DNA, should be cautious because sex-specific migration and sampling issues may have dramatic effects.

Adult↗
PubMed1997

Genetic variation in cholesterol absorption efficiency among inbred strains of mice.

The initial study utilized the outbred Black Swiss, the inbred 129/SvEv and their hybrid mice to test for possible genetic difference in cholesterol absorption efficiency. Female mice (10-12 wk old) were fed a lipid test meal containing [3H]cholesterol and beta-[14C]sitosterol by stomach tube. The amount of [3H]cholesterol excreted in the feces was determined as nonabsorbed cholesterol and was normalized based on the recovery of the nonabsorbable beta-[14C]sitosterol. The Black Swiss mice absorbed significantly less cholesterol than the 129/SvEv mice within a 24-h period. Cholesterol absorption efficiency of the hybrid mice varied widely and did not segregate with either parental group. Differences in cholesterol absorption efficiency were also observed among six different inbred strains of mice fed either a basal low fat diet or a high fat/high cholesterol diet for 3 wk. Cholesterol absorption efficiency did not differ among DBA/2, C57BL/6, C3H/He, BALB/c and AKR/J mice under basal dietary conditions. However, cholesterol absorption was significantly lower in the DBA/2 mice than in C57BL/6 and C3H/He mice after mice were fed a high fat/high cholesterol diet. Cholesterol absorption by the C57L/J mice did not differ from that of C57BL/6, C3H/He, BALB/c and AKR/J mice under basal diet conditions, but was significantly lower when mice were fed a high fat/high cholesterol diet. Cholesterol absorption efficiency differed between DBA/2 and C57L/J mice under both dietary conditions. These results suggest that cholesterol absorption is controlled by multiple genetic factors.

Absorption↗
PubMedDate not supplied

Discontinuous genetic variation among mesophilic Naegleria isolates: further evidence that N. gruberi is not a single species.

Naegleria isolates which are currently placed in the type species N. gruberi display great genetic, physiological and morphological heterogeneity. There are two possible interpretations of the nature of this species--that N. gruberi is a species complex or that it is a single continuously variable species. To distinguish between these alternatives, allelic states were determined for 33 loci in 74 new isolates selected to represent wide geographic sources and diverse temperature limits for growth. The results were compared with data for culture collection strains of N. gruberi and other species in the genus. The isolates formed a discontinuous series of clusters, separated by genetic distances similar to those separating the better-characterised taxa N. fowleri, N. lovaniensis, N. jadini, N. australiensis australiensis and N. australiensis italica. Culture collection strains assigned to N. gruberi fell into six distinct clusters, while other clusters were not represented by reference strains. The data are most consistent with the interpretation that N. gruberi is a group of several distinct species, each equivalent to the recently described species in the genus. Naegleria andersoni andersoni and N. andersoni jamiesoni also formed two distinct clusters, equivalent to species. Characteristics temperature limits for growth show that the mesophilic species are ecological as well as genetic entities.

Alleles↗
PubMed2002

Expressed sequence tags for the chicken genome from a normalized 10-day-old white leghorn whole-embryo cDNA library. 3. DNA sequence analysis of genetic variation in commercial chicken populations.

Single nucleotide polymorphisms (SNPs) have emerged as a major class of DNA markers with the advantage of permitting the development of high-density genetic maps adequate for quantitative trait loci (QTL) identification by linkage-disequilibrium analysis. Here we describe results of a relatively high-depth survey of chicken broiler and layer populations for SNPs in targeted genomic regions of chicken expressed sequence tag (EST) sites. The sequences scanned, representing the composite sequence of 12 amplified fragments for a total of 6489 bp, were randomly distributed, occurring on six different chromosomes or linkage groups in the chicken genome. Although one of the genomic DNA sequences did not match the reference cDNA sequence, another contained an intron that separated two putative exons. The number of SNPs observed within each of the 12 EST-targeted genomic regions ranged from 0 to 10 for a total of 44 and a frequency of 0.7%. About 70% of the polymorphisms were shared between layer and broiler populations. The average heterozygosity within the populations ranged from 0.15 to 0.48, with the layer populations showing the higher heterozygosity. SNPs and oligonucleotides described will provide a resource for genetic analysis in commercial chicken populations. The data appear to indicate that the relative frequency of SNPs in the targeted regions scanned is higher than the frequency reported for any of the other regions scanned to date in other eukaryotic genomes. Additionally, the results suggest that the use of DNA pools may offer an efficient approach to SNP detection in chickens, as has been shown in other vertebrates.

Animals↗