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PubMed2003

Accuracy of marker-assisted selection with auxiliary traits.

Genetic information on molecular markers is increasingly being used in plant and animal improvement programmes particularly as indirect means to improve a metric trait by selection either on an individual basis or on the basis of an index incorporating such information. This paper examines the utility of an index of selection that not only combines phenotypic and molecular information on the trait under improvement but also combines similar information on one or more auxiliary traits. The accuracy of such a selection procedure has been theoretically studied for sufficiently large populations so that the effects of detected quantitative trait loci can be perfectly estimated. The theory is illustrated numerically by considering one auxiliary trait. It is shown that the use of an auxiliary trait improves the selection accuracy; and, hence, the relative efficiency of index selection compared to individual selection which is based on the same intensity of selection. This is particularly so for higher magnitudes of residual genetic correlation and environmental correlation having opposite signs, lower values of the proportion of genetic variation in the main trait associated with the markers, negligible proportion of genetic variation in the auxiliary trait associated with the markers, and lower values of the heritability of the main trait but higher values of the heritability of the auxiliary trait.

Animals↗
PubMed2002

The power and statistical behaviour of allele-sharing statistics when applied to models with two disease loci.

We have evaluated the power for detecting a common trait determined by two loci, using seven statistics, of which five are implemented in the computer program SimWalk2, and two are implemented in GENEHUNTER. Unlike most previous reports which involve evaluations of the power of allele-sharing statistics for a single disease locus, we have used a simulated data set of general pedigrees in which a two-locus disease is segregating and evaluated several nonparametric linkage statistics implemented in the two programs. We found that the power for detecting linkage using the S(all) statistic in GENEHUNTER (GH, version 2.1), implemented as statistic E in SimWalk2 (version 2.82), is different in the two. The P values associated with statistic E output by SimWalk2 are consistently more conservative than those from GENEHUNTER except when the underlying model includes heterogeneity at a level of 50% where the P values output are very comparable. On the other hand, when the thresholds are determined empirically under the null hypothesis, S(all) in GENEHUNTER and statistic E have similar power.

Alleles↗
PubMed1999

The 677T genotype of the common MTHFR thermolabile variant and fasting homocysteine in childhood venous thrombosis.

Controlled data on the association of MTHFR genotypes, hyperhomocysteinaemia and their interaction with factor V G1691A with childhood thrombosis are not yet available. Therefore we conducted a case-control study comparing 141 childhood patients with venous thrombosis with 345 healthy controls. The MTHFR C677T genotypes, FV G1691A and prothrombin G20210A were evaluated; in addition, fasting homocysteine concentrations were measured in a subgroup of 60 children and 80 healthy controls. 10.4% of the healthy control population showed the MTHFR TT genotype, 34.2% the CT genotype and 55.4% the CC variant. MTHFR genotypes account for fasting homocysteine concentrations in healthy controls (CC: 5.5 micromol/l (4-7.2); CT: 7 micromol/l (3.9-9.8); TT: 12.1 micromol/l (7.7-13.3)) with an upper age-specific 95th percentile of 8.3 micromol/l. The following frequencies (patients versus controls), odds ratios (OR) and 95% confidence intervals (CI) were found for single defects: MTHFR 677TT genotype (10.6% vs. 10.4%; OR/CI: 1.02/0.54-1.93; P = 0.99) and CT genotype (43.8% vs. 34.2%; OR/CI: 2.12/1.42-3.16; P = 0.0000). A combination of FV G1691A mutation and MTHFR 677CT genotype was found in 9.9% of patients and in 2.9% of the controls (OR/CI: 3.8/1.64-8.75; P = 0.027). Fasting homocysteine median (range) concentrations in the patient group were significantly higher than in the controls (7 micromol/l (3-23) vs. 5.5 micromol/l (3-8.4): P = 0.0004), and homocysteine concentrations >8.3 micromol/l were found in 40% of patients vs. 2.5% of the controls (OR/CI: 22/2.64-183; P = 0.0003). Conclusion Data of this childhood case-control study suggest that mildly elevated fasting homocysteine concentrations >8.3 micromol/l and the CT genotype of the MTHFR C677T variant are significant risk factors for venous vascular occlusion in children.

Adolescent↗
PubMed2004

SLC22A4 and RUNX1: identification of RA susceptible genes.

Recently we reported that SLC22A4 and RUNX1 are associated with rheumatoid arthritis (RA). SLC22A4 is an organic cation transporter with unknown physiological function, and RUNX1 is a hematological transcriptional regulator that has been shown to be responsible for acute myelogenic leukemia. It is suggested that the association of RUNX1 with RA is due to its regulation of expression of SLC22A4. Because the physiological function of SLC22A4 is still unclear, further investigation is needed into how SLC22A4 affects RA susceptibility. Although the association of RUNX1 with RA was identified as a regulatory factor of SLC22A4, it is possible that RUNX1 is a key molecule in autoimmunity, as it has been reported to be associated with systemic lupus erythematosus and psoriasis, two other autoimmune diseases.

Animals↗
PubMed2003

Loci on chromosomes 2, 4, 9, and 16 for body weight, body length, and adiposity identified in a genome scan of an F2 intercross between the 129P3/J and C57BL/6ByJ mouse strains.

Mice have proved to be a powerful model organism for understanding obesity in humans. Single gene mutants and genetically modified mice have been used to identify obesity genes, and the discovery of loci for polygenic forms of obesity in the mouse is an important next step. To pursue this goal, the inbred mouse strains 129P3/J (129) and C57BL/6ByJ (B6), which differ in body weight, body length, and adiposity, were used in an F2 cross to identify loci affecting these phenotypes. Linkages were determined in a two-phase process. In the first phase, 169 randomly selected F2 mice were genotyped for 134 markers that covered all autosomes and the X Chromosome (Chr). Significant linkages were found for body weight and body length on Chr 2. In addition, we detected several suggestive linkages on Chr 2 (adiposity), 9 (body weight, body length, and adiposity), and 16 (adiposity), as well as two suggestive sex-dependent linkages for body length on Chrs 4 and 9. In the second phase, 288 additional F2 mice were genotyped for markers near these regions of linkage. In the combined set of 457 F2 mice, six significant linkages were found: Chr 2 (Bwq5, body weight and Bdln3, body length), Chr 4 (Bdln6, body length, males only), Chr 9 (Bwq6, body weight and Adip5, adiposity), and Chr 16 (Adip9, adiposity), as well as several suggestive linkages (Adip2, adiposity on Chr 2, Bdln4 and Bdln5, body length on Chr 9). In addition, there was a suggestive linkage to body length in males on Chr 9 (Bdln4). For adiposity, there was evidence for epistatic interactions between loci on Chr 9 (Adip5) and 16 (Adip9). These results reinforce the concept that obesity is a complex trait. Genetic loci and their interactions, in conjunction with sex, age, and diet, determine body size and adiposity in mice.

Animals↗
PubMed2004

A large-sample QTL study in mice: II. Body composition.

Using lines of mice having undergone long-term selection for high and low growth, a large-sample (n = approximately 1,000 F2) experiment was conducted to gain further understanding of the genetic architecture of complex polygenic traits. Composite interval mapping on data from male F2 mice (n = 552) detected 50 QTL on 15 chromosomes impacting weights of various organ and adipose subcomponents of growth, including heart, liver, kidney, spleen, testis, and subcutaneous and epididymal fat depots. Nearly all aggregate growth QTL could be interpreted in terms of the organ and fat subcomponents measured. More than 25% of QTL detected map to MMU2, accentuating the relevance of this chromosome to growth and fatness in the context of this cross. Regions of MMU7, 15, and 17 also emerged as important obesity "hot-spots." Average degrees of directional dominance are close to additivity, matching expectations for body composition traits. A strong QTL congruency is evident among heart, liver, kidney, and spleen weights. Liver and testis are organs whose genetic architectures are, respectively, most and least aligned with that for aggregate body weight. In this study, growth and body weight are interpreted in terms of organ subcomponents underlying the macro aggregate traits, and anchored on the corresponding genomic locations.

Animals↗
PubMed2004

A large-sample QTL study in mice: I. Growth.

By use of long-term selection lines for high and low growth, a large-sample (n = approximately 1,000 F2) experiment was conducted in mice to further understand the genetic architecture of complex polygenic traits. In combination with previous work, we conclude that QTL analysis has reinforced classic polygenic paradigms put in place prior to molecular analysis. Composite interval mapping revealed large numbers of QTL for growth traits with an exponential distribution of magnitudes of effects and validated theoretical expectations regarding gene action. Of particular significance, large effects were detected on Chromosome (Chr) 2. Regions on Chrs 1, 3, 6, 10, 11, and 17 also harbor loci with significant contributions to phenotypic variation for growth. Despite the large sample size, average confidence intervals of approximately 20 cM exhibit the poor resolution for initial estimates of QTL location. Analysis with genome-wide and chromosomal polygenic models revealed that, under certain assumptions, large fractions of the genome may contribute little to phenotypic variation for growth. Only a few epistatic interactions among detected QTL, little statistical support for gender-specific QTL, and significant age effects on genetic architecture were other primary observations from this study.

Animals↗
PubMed2004

Quasi-linkage: a confounding factor in linkage analysis of complex diseases?

Human linkage analysis is based on the assumption that unlinked genomic loci, particularly loci located on non-homologous chromosomes, segregate independently during meiosis. An exception to this rule is the phenomenon of quasi-linkage (QL) that describes the non-random segregation of non-homologous chromosomes, which can undermine the basic concept of linkage. Molecular mechanisms of QL are not clear; however, observations in mice and plants suggest a possible affinity between non-homologous chromosomal regions containing repetitive or like sequences. QL has not been investigated in humans. As QL may generate false linkages in genome scans of complex diseases, we sought to determine whether genomic loci detected in such genome scans exhibit QL. A number of individual markers showing linkage to schizophrenia, asthma, multiple sclerosis, inflammatory bowel disease and type-1 diabetes were tested for QL in a pairwise linkage analysis against all other markers exhibiting evidence for linkage in each specific study. The Marshfield genotype dataset of eight CEPH families was used for this purpose. The best QL lod scores generated from the analysis were within the range of the "lukewarm" lod scores reported in the majority of linkage studies for complex disorders. In addition, we performed a genome-wide QL analysis on the Marshfield family database which detected eight QL lod scores >6. The replication of the best Marshfield QL scores was performed using the deCODE families and although none of the eight pairs demonstrated independent evidence for QL, three pairs generated maximal lod scores of 0.11, 0.3, and 1.51. In conclusion, although complex disease relevant markers did not produce high QL lod scores, the general phenomenon of QL in humans cannot be excluded and potentially can be a confounding factor in genetic studies of complex traits.

Asthma↗
PubMed2004

High throughput multiple combination extraction from large scale polymorphism data by exact tree method.

Single nucleotide polymorphisms (SNPs) are increasingly becoming important in clinical settings as useful genetic markers. For the evaluation of genetic risk factors of multifactorial diseases, it is not sufficient to focus on individual SNPs. It is preferable to evaluate combinations of multiple markers, because it allows us to examine the interactions between multiple factors. If all the combinations possible were evaluated round-robin, the number of calculations would rapidly explode as the number of markers analyzed increased. To overcome this limitation, we devised the exact tree method based on decision tree analysis and applied it to 14 SNP data from 68 Japanese stroke patients and 189 healthy controls. From the obtained tree models, we succeeded in extracting multiple statistically significant combinations that elevate the risk of stroke. From this result, we inferred that this method would work more efficiently in the whole genome study, which handles thousands of genetic markers. This exploratory data mining method will facilitate the extraction of combinations from large-scale genetic data and provide a good foothold for further verificatory research.

Adult↗
PubMed1999

Association of diffuse panbronchiolitis with microsatellite polymorphism of the human interleukin 8 (IL-8) gene.

Diffuse panbronchiolitis (DPB) is a distinctive chronic inflammatory lung disease predominantly found in Asian populations. Although its etiology is unknown, DPB is considered to be a multifactorial disease of whose susceptibility is determined by genetic predisposition unique to Asians. We and others have previously reported that the B*5401 allele of the human leukocyte antigen (HLA)-B gene or a closely linked gene in the HLA region on 6p21.3 is one of the major genetic factors in susceptibility to this disease. However, the association with B*5401 is not absolute and the contribution of other genetic or environmental factors should also be considered. Here, four candidate genes that are postulated to play a role in the pathophysiology of DPB, namely, RON-kinase, CYP3A4, motilin, and interleukin (IL)-8, were chosen, and association studies between microsatellite markers at these loci and DPB were conducted. We demonstrated the presence of a specific allele at the IL-8 locus was associated with the disease (c2 = 9.13; P = 0.0025; corrected P [Pc] < 0.05). Although further studies are needed to examine whether neutrophil accumulation in the airways of patients with DPB is controlled by a possible genetic variation of IL-8 or other chemokine genes located in the region 4q12-q13, our data suggest that genes other than those of the HLA system may also contribute to a genetic predisposition to DPB.

Asian People↗
PubMed2026

Advancing genetic evaluation of milk yield and composition using a genomic-polygenic model in smallholder dairy cattle farms in Thailand.

Improving the accuracy of genetic evaluation in smallholder dairy systems is essential for sustainable productivity. However, traditional polygenic models (PM) are often constrained by incomplete pedigree, heterogeneous management, and limited genotyping resources. This study evaluated a genomic-polygenic model (GPM) relative to a PM using data from a multibreed dairy population raised under Thai tropical smallholder conditions. Phenotypic records for 305-day milk yield (MY), fat percentage (FP), protein percentage (PP), and somatic cell count (SCC) from 14,417 first-lactation cows across 1,321 farms were analyzed together with genotypes from 5,479 animals generated using GeneSeek Genomic Profiler (GGP) arrays ranging from 9&#xa0;K to 150&#xa0;K SNPs. Both models included herd-year-season of calving, age at first calving, and heterosis as fixed effects, and additive genetic and residual components treated as random. The GPM yielded higher additive genetic variances and heritability estimates and produced more biologically consistent antagonistic correlations among traits than the PM. Prediction accuracy was improved for all animal groups under the GPM, with the largest gain observed in genotyped young sires (18.36%). Pedigree connectedness analysis indicated that genotyping animals with low to moderate relationships enhances accuracy cost-effectively. Despite persistent challenges associated with heterogeneous management and limited pedigree depth, the results demonstrate the practical value of genomic-polygenic evaluation for smallholder multibreed dairy populations in tropical environments.

Animals↗
PubMed2000

Genetic contributions to left ventricular hypertrophy.

Left ventricular (LV) hypertrophy is a common condition that profoundly affects morbidity and mortality from cardiovascular diseases, including myocardial infarction, congestive heart failure, and stroke. Noninvasive imaging methods have greatly expanded our ability to evaluate cardiac structural and functional characteristics, and enhanced our understanding of the natural history of LV hypertrophy. The etiology of LV hypertrophy is likely due to the effects of multiple genes interacting with other genes and the environment. Although hypertension is recognized as a strong determinant of LV hypertrophy, blood pressure explains only a limited amount of the interindividual variation in LV mass. Moreover, LV hypertrophy occurs in the absence of hypertension, and in some cases precedes its development. Genes encoding proteins involved in the structure of the LV, as well as genes encoding cell signal transduction, hormones, growth factors, calcium homeostasis, and blood pressure, are likely candidates for the development of common forms of LV hypertrophy. An overview of the epidemiology and pathophysiology of LV hypertrophy and dysfunction is provided, in addition to evidence of the genetic basis for LV hypertrophy.

Black People↗
PubMed2026

Advancements in the Understanding of the Genetics of Obsessive-Compulsive Disorder (OCD).

PURPOSE OF REVIEW: This review summarizes recent advances in the genetics of Obsessive-Compulsive Disorder (OCD), their contribution to understanding disorder biology, and implication for clinical translation. RECENT FINDINGS: Recent GWAS identified 30 genome-wide significant loci and prioritized 25 putatively causal genes. Rare variant studies implicated specific genes, including CHD8, CELSR3, SLITRK5, and QRICH1. Evidence from common and rare variants support brain- and immune-related pathways. Genetic overlap with obsessive compulsive symptoms and other psychiatric disorders indicate shared underlying biology. Current evidence is largely based on individuals of European ancestry, although global efforts are underway to improve ancestral diversity in OCD genetics. Given the urgent need for improved treatment, genetically informed clinical translation approaches hold promise, including pharmacogenetics and drug repurposing. Recent advances in OCD genetics support a highly polygenic architecture, implicate specific neuro-biological and immune pathways, and provide new opportunities for clinical translation.

Humans↗
PubMed2025

Exploring depression treatment response by using polygenic risk scoring across diverse populations.

Treatment-resistant depression (TRD), usually defined as limited or no response to at least two antidepressants, occurs in approximately one-third of individuals diagnosed with major depressive disorder (MDD). Studies of individuals of European ancestry highlight a genetic overlap between TRD and MDD. We analyzed two large and diverse biobanks, the UCLA ATLAS Community Health Study (ATLAS) and the All of Us Research Program (AoU), to test for associations between a polygenic score for major depression (MDD-PGS) and TRD. Compared to treatment responders, TRD individuals have higher MDD-PGS across all ancestries. MDD-PGS was significantly associated with response to selective serotonin reuptake inhibitors in individuals of European and Hispanic/Latin American genetic ancestries in both biobanks. In AoU, a decreased MDD-PGS was observed in response to tricyclics or serotonin modulators in individuals of European American ancestry and in response to serotonin and norepinephrine reuptake inhibitors in individuals of African American ancestry. ATLAS found that MDD-PGS showed lower odds of responding to atypical agents than did TRD in MDD-affected individuals belonging to the Hispanic/Latin American group, MDD-PGS was associated with atypical agents. Overall, by leveraging larger sample sizes from two diverse biobanks, we provide new insights into antidepressant response and treatment specificity for MDD in individuals of diverse genetic ancestries.

Adult↗
PubMed2025

Leveraging local ancestry and cross-ancestry genetic architecture to improve genetic prediction of complex traits in admixed populations.

The broader application of polygenic risk score (PRS) is hindered by the limited transferability of PRS developed in Europeans to non-European populations. While many statistical methods have been developed to improve the performance of PRS in non-European populations, most of them focused on discrete genetic ancestry clusters and did not consider admixed individuals. Admixed individuals pose a unique challenge for PRS calculation due to the complexity of local ancestry and cross-ancestry effect sizes. Here, we present a statistical method called SDPR_admix for calculating PRS in admixed individuals. SDPR_admix characterizes the joint distribution of the effect sizes of a genetic variant with two ancestries to be both zero, ancestry enriched, or shared with correlation. SDPR_admix outperformed other methods in simulations and improved the prediction of real traits in European-African admixed individuals in UK Biobank when trained on the Population Architecture using Genomics and Epidemiology (PAGE) dataset (N = 13,000). Deployment of SDPR_admix on All of Us (N = 52,000) further increased the prediction accuracy by approximately 5-fold on average compared with training on PAGE. This enhancement was achieved with manageable computational time and cost, demonstrating the feasibility of training PRS models on large-scale All of Us data. We provided several examples demonstrating that both ancestral-enriched and shared effects, as included in the SDPR_admix prediction model, are helpful for improving polygenic prediction in admixed populations. We also applied SDPR_admix to construct PRS for admixed Americans with mixture of European and Amerindigenous ancestries and showed that SDPR_admix overall outperformed other methods.

Humans↗
PubMed2026

Additive value of polygenic risk and family history for coronary heart disease risk stratification in two diverse US cohorts.

Whether polygenic risk, monogenic familial hypercholesterolemia (FH), and family history (FamHx) are additively informative for coronary heart disease (CHD) risk prediction across self-identified race/ethnicity (SIRE) groups has not been established. In two diverse cohorts-Electronic Medical Records and Genomics (eMERGE) phase IV (eIV; n = 19,348) and All of Us (AoU; n = 239,645)-we quantified the associations of a polygenic risk score (PRSCHD), pathogenic/likely pathogenic variants in genes associated with FH, and FamHx with CHD and evaluated their incremental value when added to the pooled cohort equations (PCEs). CHD was defined as myocardial infarction, unstable angina, or coronary revascularization. We modeled associations with multivariable logistic regression (prevalent CHD in eIV) and Cox proportional hazards (incident CHD in AoU) and characterized predictive performance with the c-statistic and reclassification and decision-curve net benefits across actionable 10-year risk thresholds. The effects of PRSCHD and FamHx were independent and additive in both cohorts and consistent across White, Black, and Latino SIRE groups. In eIV, adding PRSCHD and FamHx to the PCE increased the c-statistic for prevalent CHD from 0.719 to 0.753 (p-diff = 9.1 &#xd7; 10-3) and reclassified 18.8% of participants at the 7.5% 10-year threshold, yielding approximately 4 additional true-positive CHD identifications per 1,000 screened. Net benefit gains were observed between the 7.5% and 10% thresholds across all three SIRE groups. In conclusion, PRSCHD and FamHx were independently and additively associated with CHD across major SIRE groups in two diverse cohorts in the United States (US), motivating the addition of these factors to clinical risk algorithms.

Humans↗
PubMed2026

Shared genetic architecture and therapeutic targets across paediatric immune-mediated diseases.

OBJECTIVES: Paediatric-onset immune-mediated inflammatory diseases (IMIDs), including juvenile idiopathic arthritis and related rheumatic diseases, remain genetically undercharacterised. We aimed to define shared and category-specific genetic architecture across paediatric IMIDs, compare signals with adult IMIDs, and identify therapeutic opportunities. METHODS: We analysed 24 paediatric IMIDs classified as autoimmune, polygenic-autoinflammatory, mixed-pattern, or allergic. Genome-wide association analyses included 18,086 cases and 131,019 controls of European ancestry. We estimated single nucleotide polymorphism (SNP)-based heritability, genetic correlations, and polygenic overlap; performed subset-based meta-analysis; and conducted functional annotation, gene prioritisation, pathway and protein network analyses, adult-IMID comparison, and drug-target prioritisation. RESULTS: SNP-based heritability ranged from 28.9% for allergic IMIDs to 61.9% for autoimmune IMIDs. Genetic correlation and polygenic modelling supported partial sharing across categories with category-specific components. Meta-analysis identified 39 genome-wide significant loci outside the Major Histocompatibility Complex (MHC) region, including 15 previously unreported loci; 19 loci were shared between categories. Gene-prioritisation and protein interaction analyses identified a core MHC-centred antigen-presentation network, with category-enriched modules involving complement, innate/barrier pathways, epithelial biology, and type 2 immunity. Enriched pathways included nuclear factor &#x3ba;B signalling, T helper 17 related pathways, Janus kinase-signal transducer and activator of transcription signalling, programmed cell death protein 1/programmed death&#x2011;ligand 1, cytotoxic T&#x2011;lymphocyte associated protein 4 regulation, and osteoclast differentiation, several of which are relevant to rheumatic diseases. Paediatric IMIDs shared broad polygenic architecture with adult IMIDs, whereas top-ranked genes converged strongly with adult rheumatic diseases. Priority Index analysis identified 178 high-scoring genes, including 43 approved or investigational IMID drug targets. CONCLUSIONS: Paediatric-onset IMIDs share core pathways with adult forms but exhibit distinct genetic architecture shaped by age-specific immune and neurodevelopmental biology. These findings provide a genomic framework for paediatric precision medicine, guiding classification, risk prediction, and therapeutic development.

Humans↗