Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “complex trait”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 901 records · Page 50Linked to original sources
PubMed2004

Ahl3, a third locus on mouse chromosome 17 affecting age-related hearing loss.

Genetic variation in humans probably plays a role in determining the range of individual susceptibility to age-related hearing loss (AHL), but no contributing loci have been identified because of the difficulties of dissecting complex traits in humans. This paper reports mapping of an AHL locus using a panel of consomic mice between C57BL/6J (B6) and MSM strains, which covered more than a half of chromosome sets. B6 strain exhibited AHL beginning at 10 months of age whereas MSM strain, derived from Japanese wild mice, had normal hearing throughout life. Individuals in the panel were examined with auditory brainstem response (ABR) at various months of age, revealing that one particular strain (B6-Chr17(MSM)) substituting the chromosome 17 with the MSM-derived one showed a prominent resistance, having still good hearing at 18 months of age. Subsequent mapping using 89 individuals in the cross between B6-Chr17(MSM) and B6 was performed, which showed a significant association of ABR thresholds with loci in the vicinity of D17Mit119. These results show a novel AHL-resistant locus, designated as Ahl3, on the chromosome 17.

Age Factors↗
PubMed2005

No major effect of the insulin-like growth factor I gene on bone mineral density in premenopausal Chinese women.

Osteoporosis is a major public health problem, mainly characterized by low bone mineral density (BMD). BMD is a complex trait that is determined by multiple genes. Insulin-like growth factor I (IGF-I) is an important growth factor of bone and thus IGF-I gene has been considered as an attractive candidate gene for osteoporosis. A few studies on the relationship between variants of the IGF-I gene and BMD variation, via traditional association and/or linkage methods, have yielded conflicting results. In this study, we simultaneously tested association and/or linkage of a cytosine-adenine (CA) repeat polymorphism at 1 kb upstream of the transcription initiation site of the IGF-I gene with BMD variation in a large cohort of premenopausal Chinese women. A total of 1263 subjects from 402 Chinese nuclear families were examined. Each family consists of both parents and at least one daughter aged between 20 and 45 years. BMDs (g/cm(2)) at the lumbar spine and hip were measured using dual-energy X-ray absorptiometry (DXA). Applying the QTDT (quantitative transmission disequilibrium tests) progam, we did not find significant evidence of association or linkage between the CA repeat polymorphism of the IGF-I gene and BMD variation at any skeletal site. Our data do not support the IGF-I gene having major effect on BMD variation in premenopausal Chinese women.

Alleles↗
PubMed2005

Genetic and environmental determinants of bone mineral density in Chinese women.

BMD is a complex trait determined by genetic and lifestyle factors. To assess the genetic and environmental determinants of BMD in southern Chinese women, we studied a community-based cohort of 531 pre- and postmenopausal southern Chinese women and assessed the influence of 12 candidate gene loci and lifestyle risk factors on spine and hip BMD. The candidate genes studied include estrogen receptor alpha (ESR1) and beta (ESR2), calcium sensing receptor (CASR), vitamin D receptor (VDR), collagen type Ialpha1 (COLIA1), and LDL receptor-related protein 5 (LRP5). Social, medical, reproductive history, dietary habits and lifestyle factors were determined using a structured questionnaire. Single nucleotide polymorphisms (SNPs) of the COLIA1 and LRP5 gene in Chinese were determined by direct sequencing. Nucleotide (nt) -1363C/G and -1997 G/T of COLIA1, nt 266A/G, 2220C/T and 3989C/T of LRP5 gene were analyzed. Using stepwise multiple linear regression analyses, body weight was the strongest predictor for BMD in premenopausal women (n = 262), which accounted for 15.9% of the variance at the spine, 20% at femoral neck, 17.1% at trochanter, 24.3% at total hip and 10.9% at the Ward's triangle. Other significant predictors were ESR1 Ivs1-397T/C genotype (2.2% at the spine); LRP5 2220C/T genotype (1.3% at the spine, 1.6% at the trochanter); LRP5 266A/G genotype (1.1% at Ward's triangle); age at menarche (1.3% at trochanter) and age (2.0% at Ward's triangle). As for postmenopausal women (n = 269), body weight ( approximately 25% at various sites) and age (approximately 16% at femoral neck, trochanter, total hip and Ward's triangle sites) were the strongest predictors of BMD. Other significant predictors were age at menarche (4.4% at spine, 0.7% at femoral neck, 1.4% at trochanter, and 1.4% at Ward's triangle); weight bearing physical activity (2.1% at trochanter and 1% at total hip); calcium intake (1.1% at femoral neck, 0.9% at trochanter, and 1.7% at total hip) ; height (0.7% at trochanter); and ESR2 1082A/G genotype (0.8% at trochanter). We conclude that BMD at various sites and at different time span of a woman is modified by different genetic and lifestyle factors, suggesting that BMD is highly dependent on gene-environmental interactions.

Base Sequence↗
PubMed2006

Solution for underflow problem in linkage and segregation analysis.

Finding genes for complex traits is one of the major challenges of modern human genetics. Current developments of molecular techniques facilitated use of large pedigrees and marker sets of thousands of single-nucleotide polymorphisms (SNPs). However, one of the problems occurring in statistical analysis of such large data sets is that the likelihood is very low and underflow may easily occur. In this work we describe a method permitting to avoid underflow during computation of a likelihood function, using different algorithms. Our method makes practically possible analysis of thousands of individuals and thousands of SNPs. The method is easy to implement without major change of the code of existing programs. It also helps to reduce the amount of computer memory used in analysis without noticeable alteration of the program running time. The algorithm was implemented in the software packages for segregation and linkage analysis, which are available from http://mga.bionet.nsc.ru/.

Algorithms↗
PubMed2005

Mass extinctions.

Factors influencing the evolution of complex traits such as body size are notoriously difficult to study but a new review of work on marine iguanas in the Galapagos islands suggests an answer may lie in the interplay of natural and sexual selection.

Biodiversity↗
PubMed2006

Familial aggregation of metabolic syndrome among the Chinese: report from the Chin-Shan community family study.

Genetic study on metabolic syndrome is a great challenge, due to its complex traits and the pleiotropic manifestation of atherosclerosis. Familial aggregation and recurrence risk ratio can provide the insight of possible genetic mechanism. The Chin-Shan community family study was based on adolescent probands and their relatives (1356 subjects) who were recruited from one junior high school in the community. Structured questionnaires and biochemical measures were obtained in standard procedures. Definition of metabolic syndrome was followed using the criteria defined by the third adult treatment panel, with a modification of the criteria for adolescent and Asian population. Grandmothers had the highest frequencies (70%) in metabolic syndrome and various atherosclerotic risks. Three factors were found and thus explained 68% of the overall variance. Estimated heritability was the highest in LDL and cholesterol factor (0.36 and 0.40), then blood pressure/obesity factor (0.27), and insulin resistance/dyslipidemia (0.27). Recurrence risk ratio among siblings was 2.95 (95% confidence interval [CI]: 1.39-6.26). The adjusted odds ratio (OR) of proband's metabolic syndrome status was 1.99 (95% CI: 1.08-3.66). The adjusted odds ratios for the three factors for predicting metabolic syndrome were all significant, with highest risk in blood pressure/obesity factor (OR: 1.27, CI: 1.22-1.33), then insulin resistance/dyslipidemia (OR: 1.29, CI: 1.16-1.23). This study demonstrated clearly familial aggregation and recurrence risk ratio of metabolic syndrome and components among the general ethnic Chinese population in Taiwan.

Adolescent↗
PubMed2005

Multilocus analyses of estrogen-related genes reveal involvement of the ESR1 gene in male infertility and the polygenic nature of the pathology.

OBJECTIVE: To examine whether polymorphisms within the ESR1, FSHR, ESR2, CYP19A1, and NRIP1 genes are susceptibility factors for human male idiopathic infertility and to test the joint effects of these genes on male reproductive function. DESIGN: Genetic association study of male infertility with polymorphisms, using both single-gene and multilocus approaches. SETTING: Private and public fertility units and a private center for biomedical research. PATIENT(S): One hundred four Spanish men with azoospermia or severe oligozoospermia and 95 unselected race-matched healthy controls from the same geographic region. INTERVENTION(S): Peripheral blood extraction, DNA purification, and ESR1 g.938T>C, FSHR Ser680Asn, ESR2 *39A>G, CYP19A1 *19C>T, and NRIP1 Gly75Gly polymorphism analyses. MAIN OUTCOME MEASURE(S): Single-gene statistical analyses and multilocus statistical analyses with Sumstat, Permutation and Model-free analysis, and Estimating Haplotypes software. RESULT(S): We observed an excess of homozygous infertile men for the ESR1 g.938T>C marker. Multilocus analyses detected genetic interaction between the five candidate gene markers that are influential over male infertility. In addition, we detected a five-loci protector genetic pattern with a frequency of 9.4% in controls but absent in infertile men. CONCLUSION(S): Our results support a relevant role for the estrogenic pathway, notably the ESR1 gene, in human male reproductive function and advocate a complex trait model for male infertility.

Alleles↗
PubMed2005

Fungal virulence, vertebrate endothermy, and dinosaur extinction: is there a connection?

Fungi are relatively rare causes of life-threatening systemic disease in immunologically intact mammals despite being frequent pathogens in insects, amphibians, and plants. Given that virulence is a complex trait, the capacity of certain soil fungi to infect, persist, and cause disease in animals despite no apparent requirement for animal hosts in replication or survival presents a paradox. In recent years studies with amoeba, slime molds, and worms have led to the proposal that interactions between fungi and other environmental microbes, including predators, select for characteristics that are also suitable for survival in animal hosts. Given that most fungal species grow best at ambient temperatures, the high body temperature of endothermic animals must provide a thermal barrier for protection against infection with a large number of fungi. Fungal disease is relatively common in birds but most are caused by only a few thermotolerant species. The relative resistance of endothermic vertebrates to fungal diseases is likely a result of higher body temperatures combined with immune defenses. Protection against fungal diseases could have been a powerful selective mechanism for endothermy in certain vertebrates. Deforestation and proliferation of fungal spores at cretaceous-tertiary boundary suggests that fungal diseases could have contributed to the demise of dinosaurs and the flourishing of mammalian species.

Animals↗
PubMed2005

Mutation in ABCA1 predicted risk of ischemic heart disease in the Copenhagen City Heart Study Population.

OBJECTIVES: We tested whether heterozygosity for the K776N mutation (frequency: 0.4%) in ATP-binding cassette transporter A1 (ABCA1) predicted ischemic heart disease (IHD) in the Copenhagen City Heart Study population. BACKGROUND: In a complex trait like IHD, genetic variation is considered to be conferred by common DNA polymorphisms, although rare mutations may have a larger impact. Tangier disease, a rare high-density lipoprotein cholesterol (HDL-C) deficiency syndrome with IHD, is caused by homozygous ABCA1 mutations. METHODS: We analyzed blood samples from a large cohort study of 9,076 Danish individuals followed for 24 years (167,287 person-years), during which 1,033 incident IHD events occurred. The hypothesis was retested in an independent case-control study comparing 562 IHD patients with 3,103 controls. RESULTS: The cumulative incidence of IHD as a function of age was increased in K776N heterozygotes compared with non-carriers (log-rank test: p = 0.005). At the age of 80 years, 48% of heterozygotes and 23% of non-carriers had IHD. Incidence rates in non-carriers and K776N heterozygotes were 61 and 157 per 10,000 person-years. The age-adjusted hazard ratio for IHD in K776N heterozygotes versus non-carriers was 2.4 (95% confidence interval 1.3 to 4.5). Adjusting for HDL-C, or for smoking, diabetes, and hypertension did not change the result, suggesting that genotype predicted risk of IHD beyond that offered by HDL-C, and by other conventional risk factors. Similar trends were obtained in an independent case-control study. CONCLUSIONS: Heterozygosity for an ABCA1 mutation (K776N) conferred two- to three-fold risk of IHD in 37 participants in the Copenhagen City Heart study.

ATP Binding Cassette Transporter 1↗
PubMed2006

The genetics of atopic dermatitis.

Atopic dermatitis (AD) is a chronic itching (pruritic) skin disease. It results from a complex interplay between strong genetic and environmental factors. Genome screens of families with AD have implicated chromosomal regions that overlap with other skin diseases and with inflammatory and autoimmune diseases. These, together with candidate gene studies, provide novel insights into the pathogenesis of AD. The findings suggest a common theme of generalized epidermal dysfunction manifesting as a compromised skin barrier and failure to protect against, or aberrant responses to, microbial insults and antigens. Recent genetic advances with high-throughput methods for gene identification, such as DNA microarrays and whole-genome genotyping, will help further dissect this complex trait. This will aid disease-defining criteria and focused therapies for AD.

Chymases↗
PubMed2004

Dissecting chill coma recovery as a measure of cold resistance: evidence for a biphasic response in Drosophila melanogaster.

Cold resistance in insects has traditionally been measured in terms of survival following a stress, but alternative methods are increasingly being used because of their relevance to the ecology of organisms and their utility in characterizing variation among species, populations and individuals. One such method capable of discriminating among Drosophila species and conspecific Drosophila populations from different environments is adult chill coma recovery time, the time taken for adults to become active again after being knocked down by a cold stress. Here we characterized the chill coma response of D. melanogaster in detail. Adults were exposed to a range of temperatures and stressful periods prior to measuring recovery. Recovery from chill coma in D. melanogaster was biphasic; as flies were stressed under cooler temperatures, recovery times leveled off and then decreased before sharply increasing again as mortality starts to occur. This biphasic response has previously been observed in D. subobscura where it has a somewhat different shape. A second mechanism therefore acts at relatively lower temperatures to ameliorate the effects of the cold stress. When D. melanogaster were reared at 19 and 25 degrees C for two generations, the shape of the curve relating temperature to recovery time was similar, but flies from the warmer temperature had longer recovery times and showed responses that leveled off and then decreased at relatively higher temperatures. As exposure time to cold stress was increased, recovery times also increased except at mild stress levels. Chill coma recovery in D. melanogaster is a complex trait and likely to reflect multiple underlying components.

Acclimatization↗
PubMed2004

No association of endometriosis with glutathione S-transferase M1 and T1 null mutations in a Japanese population.

OBJECTIVE: Endometriosis is inherited as a complex trait, which means that multiple susceptibility genes interact with each other and with environmental factors to produce the phenotype. We investigated the frequency of glutathione S-transferase M1 and T1 (GSTM1 and GSTT1) null mutations in women with endometriosis in a Japanese population. METHODS: One hundred fourteen unrelated women with endometriosis were enrolled. Samples of umbilical cord blood obtained from 179 female newborn infants were used as population controls. Genomic DNA isolated from endometriosis patients and controls were subjected to multiple polymerase chain reactions to determine the GSTM1 and GSTT1 genotypes. RESULTS: There were no significant differences in the frequencies of the GSTM1 (P = .83, odds ratio 0.95) and GSTT1 (P = .24, odds ratio 0.75) null mutations between endometriosis patients and controls. The endometriosis group was divided into a subgroup of stage IV disease only, but no statistically significant differences were observed in the frequency of the GSTM1 null mutation (P = .88, odds ratio 0.96, 95% confidence interval 0.57-1.63) and the GSTT1 null mutation (P = .33, odds ratio 0.77, 95% confidence interval 0.45-1.30) between any of these groups and the controls. CONCLUSION: These findings suggest that the GSTM1 and GSTT1 null mutations are not likely to be associated with an increased risk of endometriosis in a Japanese population.

DNA Mutational Analysis↗
PubMed2004

Polymorphism at codon 72 of the p53 gene is not associated with endometriosis in a Japanese population.

OBJECTIVE: Endometriosis is inherited as a complex trait, which means that multiple susceptibility genes interact with each other and the environment to produce the phenotype. Previous studies have implicated p53, a tumor suppressor gene, as a factor in the development of the disease. In a Japanese population, we investigated the frequency of the p53 polymorphism in women affected with endometriosis. METHODS: We compared the distribution of the p53 codon 72 polymorphism in endometriosis cases (n = 111) and population controls consisting of female neonates (n = 180) by using polymerase chain reaction restriction fragment-length polymorphism analysis in a Japanese population. RESULTS: The frequencies of the three p53 genotypes, Arginine (Arg)/Arg, Arg/Proline (Pro), and Pro/Pro in controls were 39.4%, 41.7%, and 18.9 %, respectively. The crude genotype frequencies in the endometriosis cases were similar to those of the controls (35.2%, 48.6%, and 16.2%, respectively). Using the Arg/Arg genotype as the reference, the odds ratios of the Arg/Pro and Pro/Pro genotypes were 1.30 (95% confidence interval [CI] 0.72-1.86, P =.33) and 0.96 (95% CI 0.47-1.94, P =.91), respectively. Thus, there were no significant differences in the frequency of the p53 codon 72 polymorphism between endometriosis cases and controls in this population. The endometriosis cases with severe disease only were also evaluated, but no significant difference was observed in the frequency of the polymorphism between this subgroup and the controls. CONCLUSION: Our findings suggest that the p53 codon 72 polymorphism is unlikely to be associated with endometriosis in Japanese women.

Codon↗
PubMed2006

The use of mouse chromosome substitution strains to investigate the genetic regulation of pubertal timing.

Identification of genes underlying complex traits such as pubertal timing, is vital to our understanding of fundamental human developmental processes. Animal models can provide an important adjunct to more traditional human investigations. Within this review, we discuss the use and advantages of chromosome substitution strains in the investigation of factors that regulate the timing of the onset of puberty.

Animals↗
PubMed2004

Analysis of the threshold liability model provides new understanding of causation in autoimmune diseases.

Autoimmune diseases include a heterogeneous group of complex traits, the causes of which are essentially unknown. The threshold liability model is a hypothesis that has a significant influence on thinking about causation in these diseases. Here, I analyze this model and assess its utility in understanding causation in autoimmunity. According to the model, members of a population have a normal distribution of genetic liability for a particular autoimmune disease. Further, a threshold value exists for each autoimmune disease such that an individual develops disease when his/her liability exceeds the threshold value; environmental and stochastic factors and epistatic gene interactions may increase or decrease an individual's disease liability. There are, however, two main problems with the threshold liability model. First, for a particular autoimmune disease, the threshold value divides a population into two distinct groups that consist either of affected or of healthy individuals. I show that this dichotomous division is inaccurate and misleading. Second, the threshold value corresponds to the occurrence of a component-cause of disease, i.e. when an appropriate collection of causative factors for a particular autoimmune disease is present, the disease must inevitably occur. I argue, however, that the disease contribution of essentially unknown random or stochastic factors to causation is at least similar in importance to the contributions of genetic and environmental factors. These stochastic factors add a significant element of unpredictability to the effects of genetic and environmental factors. Consequently causes in autoimmunity do not act deterministically, which is implied by the component-cause concept. Instead, the role of causative factors is to alter disease risk. I therefore reject the threshold liability model and conclude that a probabilistic approach provides the only reasonable way to understand causation in autoimmune diseases. This conclusion has important implications for other deterministic hypotheses in autoimmunity including other component-cause hypotheses.

Autoimmune Diseases↗
PubMed2005

Clinical multiple sclerosis occurs at one end of a spectrum of CNS pathology: a modified threshold liability model leads to new ways of thinking about the cause of clinical multiple sclerosis.

Multiple sclerosis (MS) is a complex trait, the causes of which are elusive. A threshold liability model influences thinking about the causes of this disorder. According to this model, a population has a normal distribution of genetic liability to MS. In addition, a threshold exists, so that MS begins when an individual's liability exceeds the MS threshold; environmental and other causative factors may increase or decrease an individual's MS liability. It is argued here, however, that this model is misleading, as it is based on the incorrect assumption that MS is a disorder that one either has or does not have. This paper hypothesizes, instead, that patients with a diagnosis of MS share identical CNS pathology, termed MS pathology, with some individuals who have a diagnosis of possible MS and with some apparently healthy individuals, who may never have a diagnosis of MS. In order to accommodate this hypothesis, the current threshold liability model is modified as follows. (1) In addition to a normal distribution of MS liability within a population, a spectrum of MS pathology occurs in some who have a high MS liability. (2) A clinical MS threshold exists at a point on this liability distribution, where the burden and distribution of MS pathology permits a diagnosis of clinical MS. (3) Additional thresholds exist that correspond to a lower MS liability and a lesser burden of MS pathology than occur at the clinical MS threshold. This modified threshold model leads to the postulate that causes act at various time points to increase MS liability and induce MS pathology. The accumulation of MS pathology sometimes leads to a diagnosis of clinical MS. One implication of this model is that the MS pathology in clinical MS and in some with possible MS differs only in the extent but not in the type of CNS injury. Thus, it may be possible to obtain insight into the causative environmental factors that increase MS liability and induce MS pathology by focusing on patients who have clinical MS; some environmental factors that induce new lesions in patients with clinical MS may be identical to those that induce MS pathology in genetically susceptible individuals who do not have clinical MS. Identification of these causative factors has importance, as specific treatment may prevent the accumulation of MS pathology that leads to the significant CNS damage associated with clinical MS.

Central Nervous System Diseases↗
PubMed2005

Linkage study of the glucagon receptor gene with type 2 diabetes mellitus in Italians.

Type 2 diabetes mellitus (T2DM) is a common complex trait disorder. Multiple genome scans have identified different loci in linkage with T2D, including a locus on chromosome 17q24-25. Because the glucagon receptor gene ( GCR ) resides on chromosome 17q25, it might be responsible for the linkage identified in the same region. In a combined French-Sardinian study of GCR , there is an association of Gly 40 Ser mutation with T2DM, confirmed by a UK study but not by others. Our goal was to study this selected region of chromosome 17 in a group of Italian patients with late- and early-onset T2DM by genotyping the microsatellites D17S801, D17S937, and D17S1806 and by performing nonparametric multipoint linkage analysis (Merlin 2000-2002) with allele frequencies calculated from sib-pairs data. We recruited from the center of Italy late-onset sib pairs with T2DM and families with maturity-onset diabetes of the young/early-onset T2DM (N = 503). The linkage analysis at chromosome 17q25 reported no positive lod scores in the total T2D sib pairs, in the late-onset T2D group, and in the early-onset T2D group. Although the study does not show evidence for linkage in this chromosomal region in our Italian cohort, we cannot a priori exclude the possibility of an allelic or genotypic association. Nevertheless, we may conclude that GCR does not play a major role in the pathogenesis of T2DM in Italians.

Diabetes Mellitus, Type 2↗
PubMed2005

Shortened telomeres in murine scid cells expressing mutant hRAD54 coincide with reduction in recombination at telomeres.

Murine severe combined immunodeficiency (scid) cells are characterized by defective Prkdc (DNA-PKcs), one of the key genes involved in the repair of DNA double-strand breaks. Interestingly, scid mice are not null mutants and their cells are likely to show low DNA-PKcs activity. Prkdc is also involved in telomere maintenance and in contrast to mice genetically engineered to lack Prkdc (i.e. null mutants), which show complete absence of DNA-PKcs activity, loss of telomere capping function and normal telomere length, cells from scid mice show not only loss of telomere capping function but also abnormally elongated telomeres. Here we demonstrate that telomere elongation observed in murine scid cells can be reversed by expressing mutant hRAD54, a protein involved in homologous recombination. In addition, we measured recombination rates at telomeres using chromosome orientation fluorescence in situ hybridization (CO-FISH) and found that these are elevated in scid cells in comparison with control cells, or significantly reduced in scid cells expressing mutant hRAD54. Similarly, recombination rates at telomeres are reduced in scid cells following introduction of functional Prkdc. Since expression of mutant hRAD54 and restoration of functional Prkdc in scid cells cause the same effects, i.e. telomere shortening and reduced recombination rates at telomeres, these results argue that telomere elongation in scid cells is a complex trait resulting from interactions between homologous recombination mechanisms and DNA-PKcs.

Alkylating Agents↗