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Results for “Genetic overlap”

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PubMed2003

Human chromosome 7: DNA sequence and biology.

DNA sequence and annotation of the entire human chromosome 7, encompassing nearly 158 million nucleotides of DNA and 1917 gene structures, are presented. To generate a higher order description, additional structural features such as imprinted genes, fragile sites, and segmental duplications were integrated at the level of the DNA sequence with medical genetic data, including 440 chromosome rearrangement breakpoints associated with disease. This approach enabled the discovery of candidate genes for developmental diseases including autism.

Animals↗
PubMed2006

Stimulant use and symptoms of abuse/dependence: epidemiology and associations with cannabis use--a twin study.

BACKGROUND: This paper explores the magnitude of--and extent of overlap between--additive genetic, shared environmental and non-shared environmental influences on lifetime stimulant use and on stimulant abuse/dependence symptoms; the associations between stimulant use and cannabis use and the extent to which these associations can be attributed to common or correlated genetic and environmental influences. METHODS: Self-report data on lifetime stimulant use, abuse/dependence symptoms and corresponding measures of cannabis involvement were collected from a sample of 6265 male and female Australian twins born 1964-1971. RESULTS: Approximately one in five study participants reported lifetime stimulant use while 5% reported experiencing at least one symptom of abuse/dependence. Multivariate genetic model fitting indicated moderate genetic influences on stimulant use (40%) and symptoms (65%) while there was no evidence of sex differences in the magnitude of these influences. Despite some overlap in genetic influences on these measures, approximately 60% of the genetic variance in symptoms was specific to this phenotype. There were also strong genetic and shared environmental correlations between the factors associated with stimulant use and those associated with cannabis use. CONCLUSIONS: There were moderate genetic influences on stimulant use and stimulant abuse/dependence with moderate overlap between the genetic factors associated with these outcomes. Additionally, there were strong associations between measures of lifetime stimulant use and analogous measures of cannabis use which, importantly, could be largely attributed to shared familial risk factors predisposing to both stimulant and cannabis use.

Adult↗
PubMed2005

Subjective wellbeing and sleep problems: a bivariate twin study.

The relationship between subjective wellbeing (SWB) and self-reported sleep problems was investigated in a cohort of Norwegian twins aged 18 to 31 years. Questionnaire data from 8045 same- and opposite-sex twins were analyzed using structural equation modeling to explore the relative effects of genetic and environmental influences on phenotypic variance and covariance. Special attention was paid to sex-specific effects. The correlation between the phenotypes was estimated to be -.43. Univariate analyses indicated considerable genetic influences for both SWB and sleep problems, for male and female twins alike. The best fitting bivariate model specified additive genetic and individual environmental factors for both phenotypes, and nonadditive genetic effects for sleep problems, with no sex-specific effects. Genetic and environmental effects accounted for 60% and 40% of the phenotypic correlation, respectively. Additive genetic factors affecting the two phenotypes were correlated (-.85), suggesting that part of the genetic effects that positively influence SWB also protect against sleep problems. In conclusion, the results indicate considerable overlap in genetic etiology for SWB and sleep problems, for males and females alike.

Adolescent↗
PubMed2003

Genetic algorithms based on wavelet transform for resolving simulated overlapped spectra.

Wavelet transform-based genetic algorithms are proposed for resolving simulated overlapped spectra. Wavelet transform as a derivative method is used for de-noising, for deducting background absorption as well as for peak finding in order to get an estimation of parameters of unresolved spectra. Then genetic algorithms, using the estimations of parameters as input values, are employed to resolve unresolved bands. As a consequence, a good optimized solution was achieved since the reliable estimation of initial values can greatly facilitate the convergence of genetic algorithms and the calculation time is shortened accordingly.

Journal Article↗
PubMed1993

Familial influences on heart rate, blood pressure, and self-report anxiety responses to stress: results from 100 twin pairs.

Two hundred healthy adolescent to middle-aged individuals (12-44 years, M = 20 years) were tested in a standardized stress protocol. These individuals comprised 20 monozygotic female, 20 monozygotic male, 20 same-sex dizygotic female, 20 same-sex dizygotic male, and 20 opposite-sex dizygotic twin pairs. Familial influences on heart rate, blood pressure, and self-report anxiety responses to four different kinds of stressors (Visual-Verbal Test for Conceptual Thought, mental arithmetic, isometric handgrip, cold pressor) were assessed using biometrical genetic model fitting. Evidence of significant genetic effects on resting heart rate and blood pressure was obtained, providing heritability estimates of .65, .63, and .58 for resting heart rate and systolic and diastolic blood pressure, respectively. Cardiovascular reactivity to the Visual-Verbal Test, mental arithmetic, and the cold pressor test appeared to be primarily influenced by genetic and idiosyncratic (nonfamilial) environmental factors, whereas reactivity to handgrip was more related to effects of the family environment. The results of multivariate model fitting suggested that the genetic effects on reactivity were relatively independent of those affecting resting heart rate and blood pressure and that there was significant overlap of genetic influences on heart rate and blood pressure responses to the two active coping tasks.

Adolescent↗
PubMedDate not supplied

[Structural-functional characteristics of the 13q14 region of the human genome in the search for potential tumor suppressor genes].

Works on chromosome 13 mapping supported by the Russian program Human Genome are reviewed. Emphasis is placed on studies of region 13q14.3, which is often lost in some human tumors and potentially contains tumor suppressor genes (TSG). A strategy of TSG search is described. As the resolution of genome analysis improved, a minimal overlap of genetic loss in B-cell chronic lymphocytic leukemia (B-CLL) was established for chromosome 13. A map of expressed sequences was constructed for the region containing the overlap, and candidate TSG of chromosome 13q14 were identified. The candidate genes were analyzed both structurally and functionally, and their possible role in tumorigenesis was considered. Assuming haploinsufficiency as a genetic mechanism controlling B-CLL, a new strategy was proposed for mutation screening aimed at identifying potential TSG of region 13q14.

Chromosomes, Human, Pair 13↗
PubMed2001

[Using genetic algorithm for quantitative analysis of overlapped spectra in FTIR].

Technique for the quantitative analysis of FTIR spectra, which are serious overlapped in the spectral bands, is studied by genetic algorithm. The multicomponent in the mixture, which contains ten air toxic organic components, such as benzene, phenixin, chlorobenzene, nitrobenzene, phenol, toluene, methanol, o-cresol, m-cresol and p-cresol, is simultaneously determined. The effect of the probability of crossover and the establishment of objective function are discussed. The method of adaptive mutation is used. The results indicate that genetic algorithm has excellent non-linear ability of solution. Mean relative error of each results is really small, generally not bigger than 1%, when the conditions are properly controlled.

Algorithms↗
PubMed2006

Evolution of genetically correlated traits: tooth size and body size in baboons.

Within a population, only phenotypic variation that is influenced by genes will respond to selection. Genes with pleiotropic effects are known to influence numerous traits, complicating our understanding of their evolution through time. Here we use quantitative genetic analyses to identify and estimate the shared genetic effects between molar size and trunk length in a pedigreed, breeding population of baboons housed at the Southwest National Primate Research Center. While crown area has a genetic correlation with trunk length, specific linear measurements yield different results. We find that variation in molar buccolingual width and trunk length is influenced by overlapping additive genetic effects. In contrast, mesiodistal molar length appears to be genetically independent of body size. This is the first study to demonstrate a significant genetic correlation between tooth size and body size in primates. The evolutionary implications are discussed.

Animals↗
PubMed2026

Genetic and physical interactions reveal overlapping and distinct contributions to meiotic double-strand break formation in C. elegans.

Double-strand breaks (DSBs) are the most deleterious lesions experienced by our genome. Yet, DSBs are intentionally induced during gamete formation to promote the exchange of genetic material between homologous chromosomes. While the conserved topoisomerase-like enzyme Spo11 catalyzes DSBs, additional regulatory proteins-referred to as 'Spo11 accessory factors'-regulate the number, timing, and placement of DSBs during meiotic prophase, ensuring that SPO-11 does not wreak havoc on the genome. Despite the importance of the accessory factors, they are poorly conserved at the sequence level, suggesting that these factors may adopt unique functions in different species. In this work, we present a detailed analysis of the genetic and physical interactions between the DSB factors in the nematode Caenorhabditis elegans, providing new insights into conserved and novel functions of these proteins. This work shows that HIM-5 is the determinant of X-chromosome-specific crossovers and that its retention in the nucleus is dependent on DSB-1, the sole accessory factor that interacts with SPO-11. We further provide evidence that HIM-5 mediates interactions with the different accessory factors subgroups, providing insights into how components on the DNA loops may interact with the chromosome axis.

Animals↗
PubMed2005

Molecular genetic analysis of the nested Drosophila melanogaster lamin C gene.

Lamins are intermediate filaments that line the inner surface of the nuclear envelope, providing structural support and making contacts with chromatin. There are two types of lamins, A- and B-types, which differ in structure and expression. Drosophila possesses both lamin types, encoded by the LamC (A-type) and lamin Dm0 (B-type) genes. LamC is nested within an intron of the essential gene ttv. We demonstrate that null mutations in LamC are lethal, and expression of a wild-type LamC transgene rescues lethality of LamC but not ttv mutants. Mutations in the human A-type lamin gene lead to diseases called laminopathies. To determine if Drosophila might serve as a useful model to study lamin biology and disease mechanisms, we generated transgenic flies expressing mutant LamC proteins modeled after human disease-causing lamins. These transgenic animals display a nuclear lamin aggregation phenotype remarkably similar to that observed when human mutant A-type lamins are expressed in mammalian cells. LamC aggregates also cause disorganization of lamin Dm0, indicating interdependence of both lamin types for proper lamina assembly. Taken together, these data provide the first detailed genetic analysis of the LamC gene and support using Drosophila as a model to study the role of lamins in disease.

Alleles↗
PubMed2002

Psychiatric disorders in relatives of subjects with Alzheimer's disease. No evidence for common genetic risk factors.

INTRODUCTION: The clustering of two or more disorders in the same family might indicate the presence of common genetic risk factors. The prevalence of various psychiatric disorders in relatives of Alzheimer's disease (AD) patients has rarely been investigated. Consequently, family study data were reinvestigated to assess, if there are indications for an overlap of genetic risk factors of AD and other psychiatric disorders. METHOD: Family history information on 2964 living and deceased first-degree relatives of 146 AD patients, 168 patients with major depression (MD) and 136 control subjects were obtained by at least one informant. Of the living relatives, 49.2 % could also be interviewed. Best-estimate lifetime diagnoses were made on all available information. Lifetime prevalences of psychiatric disorders were compared in relatives of AD patients, of MD patients and of control subjects using chi(2) statistics. Cox proportional hazards regression analyses were additionally performed to control for the relative's age, gender and source of information (interview vs. family history information). RESULTS: Relatives of AD patients had no increased risk of other psychiatric disorder compared with relatives of the comparison groups. CONCLUSION: AD is genetically distinct from other psychiatric disorders, i. e., schizophrenia, anxiety, obsessive-compulsive, somatoform disorders, alcoholism, substance abuse or dependency.

Adult↗
PubMedDate not supplied

Assessing the contribution of breeds to genetic diversity in conservation schemes.

The quantitative assessment of genetic diversity within and between populations is important for decision making in genetic conservation plans. In this paper we define the genetic diversity of a set of populations, S, as the maximum genetic variance that can be obtained in a random mating population that is bred from the set of populations S. First we calculated the relative contribution of populations to a core set of populations in which the overlap of genetic diversity was minimised. This implies that the mean kinship in the core set should be minimal. The above definition of diversity differs from Weitzman diversity in that it attempts to conserve the founder population (and thus minimises the loss of alleles), whereas Weitzman diversity favours the conservation of many inbred lines. The former is preferred in species where inbred lines suffer from inbreeding depression. The application of the method is illustrated by an example involving 45 Dutch poultry breeds. The calculations used were easy to implement and not computer intensive. The method gave a ranking of breeds according to their contributions to genetic diversity. Losses in genetic diversity ranged from 2.1% to 4.5% for different subsets relative to the entire set of breeds, while the loss of founder genome equivalents ranged from 22.9% to 39.3%.

Animals↗
PubMed2003

Allelic variation in srtAs of Streptococcus suis strains.

Streptococcus suis NCTC10234 possesses five srtA homologs: srtA encodes sortase, which anchors surface proteins with an LPXTG motif to the cell wall, while the functions of the other four homologs (the srtBCD cluster and srtE) remain unknown. The genetic organization of the srtA region was found to be conserved in the 59 S. suis strains examined in this study. Although the srtAs in three of these strains showed strong sequence divergence, their functions were verified to be overlapping by genetic complementation, indicating the functional conservation of srtAs during the evolution of these strains. These results indicate the importance of an srtA-mediated cell wall sorting system for displaying proteins on the surface of S. suis.

Alleles↗
PubMed2006

Microsatellites reveal extensive geographical, ecological and genetic contacts between invasive and indigenous whitefly biotypes in an insular environment.

Human-mediated bioinvasions provide the opportunity to study the early stages of contact between formerly allopatric, divergent populations of a species. However, when invasive and resident populations are morphologically similar, it may be very difficult to assess their distribution in the field, as well as the extent of ecological overlap and genetic exchanges between invasive and resident populations. We here illustrate the use of data obtained from a set of eight microsatellite markers together with Bayesian clustering methods to document invasions in a group of major tropical pests, Bemisia tabaci, which comprises several morphologically indistinguishable biotypes with different agronomic impacts. We focus on the island of La Réunion, where an invasive biotype (B) has recently been introduced and now interacts with the resident biotype (Ms). The temporal and spatial distribution, host-plant range and genetic structure of both biotypes are investigated. We showed (i) that, without prior information, clustering methods separate two groups of individuals that can safely be identified as the B and Ms biotypes; (ii) that the B biotype has invaded all regions of the island, and showed no signs of genetic founder effect relative to the Ms biotype; (iii) that the B and Ms biotypes coexist in sympatry throughout most of their geographical ranges, although they tend to segregate into different host plants; and finally (iv) that asymmetrical and locus-specific introgression occurs between the two biotypes when they are in syntopy.

Animals↗
PubMed2005

Application of ITS-2 sequences as markers for identification and phylogenetic inference within the genus Geomylichus (Acari: Listrophoridae).

Phylogenetic relationships among 18 samples from nine nominal species of Geomylichus (Acari: Listrophoridae), were analyzed based on internal transcribed spacer 2 (ITS 2) sequences, Prolistrophorus sp. was used as an outgroup. Maximum likelihood and neighbor-joining analyses indicated that Geomylichus is formed by at least three internal clades. Genetic distance among Prolistrophorus and Geomylichus was 27.8-35.5%, and among species, populations, and infrapopulations of Geomylichus it was 0.4-21.8%, 0.8-2.4%, and 0.8-1.2%, respectively. Differences between the results of this analysis with conventional taxonomy of the group, as well as the overlapping of genetic distances among species, populations, and infrapopulations, suggest that the definition of species within Geomylichus deserves reconsideration. For example, the recognition of inconsistencies among G. texanus populations associated to different host species, resulting from the molecular analysis, led us to collect new morphological evidence now suggesting that this taxon represents more than one species.

Animals↗
PubMed1999

Large scale screening of the mitochondrial DNA reveals no pathogenic mutations but a haplotype associated with multiple sclerosis in Caucasians.

We report the first large-scale screening of mitochondrial (mt) DNA in 77 Caucasian patients with relapsing-remitting or secondary progressive form of multiple sclerosis (MS) and in 84 Caucasian controls by using the method of restriction site polymorphism and haplotype analysis. No pathogenic mtDNA mutation was found in association with MS. However, mtDNA haplotypes K* and J* defined by the simultaneous presence of Ddel restriction sites at nucleotides 10,394 and 14,798 of the mtDNA in haplogroups K and J showed association with MS at a P-value of 0.001. A relative increase of MS patients compared to controls either with the J* or with the K* haplotype (+10,394Ddel/+14,798Ddel in haplogroup J or K) also was detected (each with a P<0.05). No distinct phenotypic characteristics of MS were observed when clinical data of patients with haplotypes K* or J* were analyzed. In addition to previous complete sequencing in several MS patients, the population screening of mtDNA presented here suggests that mtDNA point mutations are not likely to be involved in the pathogenesis of typical forms of MS. However, the mitochondrial genetic background (haplotype K* and J*) may moderately contribute to MS susceptibility. The reported association between MS and Leber's hereditary optic nerve atrophy, a disease caused by mtDNA point mutations preferentially occurring in haplogroup J, may be at least in part related to the overlapping mitochondrial genetic background of the two diseases.

Adult↗