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Genetic overlap between depression and C-reactive protein levels: Evidence from a cross-trait analysis.

Inflammation and depression have been consistently associated, with elevated C-reactive protein (CRP) levels observed in a significant subset of affected individuals. However, the genetic mechanisms underlying this association remain poorly understood. We integrated results from large-scale genome-wide association studies (GWAS) of depression and CRP levels in a cross-trait analysis specifically focusing on identifying horizontally pleiotropic loci. Identified variants were stratified as concordant versus discordant based on their direction of effects on the two traits and followed up using functional annotation, gene set enrichment, and colocalization analyses. We also explored causal relationships using Mendelian Randomization (MR) analysis with extensive sensitivity analyses, including adjustment for body mass index (BMI). We identified 9 novel loci. Functional analyses revealed that concordant loci were enriched in genes linked to immune and inflammatory processes, while discordant loci mostly mapped to metabolic pathways, including lipid regulation. MR provided strong evidence for body mass index driving a causal relationship between the genetic liability of depression on CRP levels. Our findings suggest that the association between depression and CRP levels is partly driven by shared genetic influences, pointing to different biological pathways depending on whether genetic effects are concordant or discordant. These results underscore the importance of considering effect direction when assessing the genetic overlap between depression and inflammatory processes. In addition, they highlight BMI as a key factor in the causal relationship between depression and systemic inflammation.

C-Reactive Protein↗

Molecular mechanisms of human carcinogenesis.

Intensive research efforts during the last several decades have increased our understanding of carcinogenesis, and have identified a genetic basis for the multi-step process of cancer development. Tumors grow through a process of clonal expansion driven by mutation. Several forms of molecular alteration have been described in human cancers, and these can be generally classified as chromosomal abnormalities and nucleotide sequence abnormalities. Most cancer cells display a phenotype characterized by genomic hypermutability, suggesting that genomic instability may precede the acquisition of transforming mutations in critical target genes. Reduced to its essence, cancer is a disease of abnormal gene expression, and these genetic abnormalities contribute to cancer pathogenesis through inactivation of negative mediators of cell proliferation (including tumor suppressor genes) and activation of positive mediators of cell proliferation (including proto-oncogenes). In several human tumor systems, specific genetic alterations have been shown to correlate with well-defined histopathological stages of tumor development and progression. Although the significance of mutations to the etiological mechanisms of tumor development has been debated, a causal role for such genetic lesions is now commonly accepted for most human cancers. Thus, genetic lesions represent an integral part of the processes of neoplastic transformation, tumorigenesis, and tumor progression, and as such represent potentially valuable markers for cancer detection and staging.

Cell Transformation, Neoplastic↗

[Empirical, free of genetic model, estimation of recurrence risks in multifactorial diseases: conditional probability approach].

Conditional probability approach in estimation of recurrence risks in sibships of different parental phenotypic matings with the different set of affected and normal siblings is considered. The formulae are presented for calculation of recurrence risks in cases of equal and different susceptibility of two sexes under different ways of sampling of family data: direct selection of offsprings through the parents; indirect selection of offsprings through affected siblings--the probands, under different ascertainment probability--from pi = 1.0 ("exhaustive selection") up to pi----0 ("single selection"); for the case of different susceptibility of the two sexes a possibility of the differences in the ascertainment probabilities of men (pi m) and of women (pi w) is allowed, unlike "independent ascertainment model", which requires the constancy of pi. The case of multiple incompatible subforms is considered for estimation of the recurrence risks of the specified subforms. The methods of the risks estimation proposed are free of genetic models being universal both for classical mendelian traits (with the constant risks) and for multifactorial ones (with variable risks).

Causality↗

Causality of myelodysplasia and acute myeloid leukemia and their genetic abnormalities.

New insights into causative factors for the development of myelodysplasia (MDS) and acute myeloid leukemia (AML), with associations to specific cytogenetic and genetic abnormalities have been obtained primarily from studies of patients with the therapy-related subsets of the two diseases. Current knowledge now makes it possible to distinguish between at least seven major genetic subgroups of MDS and AML, and has directed research towards more specific causative factors also for de novo MDS and AML.

Acute Disease↗

Personality and psychopathology: genetic perspectives.

Genetic factors exert an important influence on adult personality traits, accounting for anywhere between 30% and 60% of the variance. Heredity is also important for most forms of psychopathology and plays a major role in several theories that relate personality to psychopathology. Despite this, there has been surprisingly little multivariate genetic research reported on joint analyses of personality and psychopathology. The small amount of available data suggests that genes may account for over 50% of the observed correlation between neuroticism and state symptoms of anxiety and depression. The mechanisms behind such strong genetic correlations are crucial for understanding the causal relationship between a personality trait and a disorder because genetically influenced biological systems may operate as exogenous "third-party" factors that are responsible for what appear to be phenotypic cause-effect relationships. We illustrate how recent analytical advances in behavior genetics can use multivariate family data to address questions about the causal role of personality in psychopathology.

Diseases in Twins↗

[Some aspects of individual susceptibility to cancer and approach to its prevention].

Article covers methodic approaches to tackle problems of individual propensity to malignancies. Genetic propensity to pulmonary cancer and gastric carcinoma was supported by studies using genetic markers: HLA antigens and dermatoglyphics. Dermatoglyphic picture was proved to predict possibility of malignancy more reliably than antigens.

Causality↗

[The renin-angiotensin system as the basic principle for hypertension and coronary heart diseases--role of genetic factors].

Since the discovery of renin by Tigerstedt and Bergmann, the renin angiotensin system (RAS) has been recognized as an important modulator of blood pressure and volume homeostasis. Based on these functions a pathophysiological role of the RAS in the pathogenesis of hypertension and other cardiovascular disorders has been postulated. The therapeutic benefit of RAS inhibition by angiotensin converting enzyme (ACE) inhibitors and angiotensin II (ANG II) antagonists in these conditions has been shown. It remains unclear, however, whether the changes in RAS activity associated with cardiovascular disease are primary or secondary factors. It is well known that hypertension and hypertensive end-organ disease is influenced by genetic factors. Gene polymorphisms for virtually all components of the RAS have been described and investigated in clinical studies. It remains to be determined, however, how relevant these findings are for disease etiology. This review, therefore, will attempt to discuss the causal implications of these genetic studies for cardiovascular disease. The role of angiotensinogen and ACE for hypertension, coronary artery disease and other cardiovascular disorders is discussed in this context in an exemplary fashion.

Angiotensinogen↗

Association of inflammatory bowel disease with indicators for childhood antigen and infection exposure.

BACKGROUND AND AIMS: Genetic susceptibility plays an important role in the predisposition to inflammatory bowel disease (IBD), but genetics alone cannot explain the six- to eightfold rise in incidence accompanying postwar socioeconomic changes in developed countries. It is presently unclear how environmental factors either trigger or modify the risk for and course of IBD in the presence of genetic susceptibility. PATIENTS AND METHODS: We evaluated 2,351 consecutive responses from IBD patients and from 3,364 of their unaffected first-degree relatives (parents/siblings) who completed a multi-item questionnaire with their physicians as part of a study of IBD genetics. All single-patient families were excluded from the analysis to avoid ascertainment bias, resulting in 120-133 independent cases for the analysis of environmental factors and 1,685 patients to be included in the analysis of birth rank. RESULTS: No statistically significant association was observed between the presence of IBD and the availability of either (warm) tap water, water toilets, or central heating during childhood. However, higher birth rank (> or =3) was significantly associated with a lower risk of IBD (odds ratio 0.68). CONCLUSION: Lower birth rank as a possible indicator of increased childhood infection exposure was associated with a higher risk for IBD. Future studies need to address the interaction of known genetic variations (e.g., in the NOD2 gene) with environmental factors potentially mediating this effect.

Birth Order↗

Male infertility: Y-chromosome deletion and testicular aetiology in cases of azoo-/oligospermia.

The spermatogenesis locus azoospermia factor (AZF) in Yq11 has been delineated into three microdeletion intervals designated as AZFa, AZFb andAZFc. AZFc is the most frequently deleted region. We have studied 270 male infertile patients for various genetic disorders associated with infertile phenotype. In this study, we have presented results of our studies on Y-chromosome deletions, chromosomal abnormalities (Klinefelter syndrome) and histology of testis with the objective of seeing whether there were cases of gonosomic mosaicism and a causal correlation between the genetic disorder; and testicular aetiology could be drawn. In all the 13 cases of Y-chromosome microdeletion, AZFc region and DAZ gene were deleted, while no case of AZFa deletion was detected. This result was at variance with other reports from India, where a considerable fraction of cases showed deletion in AZFa region of the Y-chromosome. Both Y-deleted and non-Y-deleted cases revealed heterogeneous testicular phenotype with comparable severity. This disparity among testicular phenotype in cases with known genetic aetiology and even in cases of unknown aetiology can be attributed to different genetic backgrounds and effect of modifiers. Since male infertility is a multifactorial disorder, the contributions of environmental and occupational insults may not be underestimated.

Biopsy↗

Causal relationships between oral-gut microbiome and bone neoplasm-related phenotypes: Insights from bidirectional Mendelian randomization.

The human oral and gut microbiota are the 4 largest microbial communities in the body and play crucial roles in maintaining homeostasis and influencing disease. Observational studies have suggested links between these microbiota and bone neoplasm-related phenotypes, but establishing causality has been challenging due to confounding factors and reverse causality. We conducted a bidirectional, 2-sample Mendelian randomization (MR) study to investigate evidence consistent with a potential causal association between the saliva and gut microbiota and various bone neoplasm-related phenotypes. Genetic instruments for saliva and gut microbiota were sourced from large genome-wide association studies. Inverse variance weighted was the primary MR method, supplemented by 4 other MR techniques. Sensitivity analyses, including MR-Egger regression, were performed to assess pleiotropy and heterogeneity. In the forward MR analysis, Veillonella parvula from the saliva microbiota was associated with a decreased risk of bone and connective tissue neoplasms (β: -0.236, 95% CI: [-0.275, -0.197], P = 8.20E-33). MR analyses identified genetically predicted associations between several microbial taxa and bone neoplasm-related phenotypes. Reverse MR analyses showed that genetic liability to bone neoplasm-related phenotypes was associated with variation in the composition of the oral (e.g., Order Bacteroidales, Rothia mucilaginosa) and gut microbiota (e.g., Class Methanobacteria, Genus Eubacterium oxidoreducens group). Sensitivity analyses confirmed the robustness of these findings, as no statistical evidence of substantial heterogeneity or directional horizontal pleiotropy was detected. This study provides genetic evidence supporting a bidirectional causal relationship between specific saliva and gut microbiota and bone neoplasm-related phenotypes. Our findings identify several microbial taxa as potential candidates for future biomarker development and therapeutic investigation in bone neoplasm-related phenotypes. However, these genetically informed associations require further mechanistic, experimental, and prospective clinical validation before clinical application.

Humans↗

Febrile seizures and mesial temporal sclerosis.

PURPOSE OF REVIEW: The sequence of febrile seizures followed by intractable temporal lobe epilepsy is rarely seen from a population perspective. However, several studies have shown a significant relationship between a history of prolonged febrile seizures in early childhood and mesial temporal sclerosis. The interpretation of these observations remains quite controversial. One possibility is that the early febrile seizure damages the hippocampus and is therefore a cause of mesial temporal sclerosis. Another possibility is that the child has a prolonged febrile seizure because the hippocampus was previously damaged by a prenatal or perinatal insult or by genetic predisposition. RECENT FINDINGS: Imaging studies have shown that prolonged and focal febrile seizures can produce acute hippocampal injury that evolves to hippocampal atrophy, and that complex febrile seizures can originate in the temporal lobes in some children. Several lines of evidence now indicate that genetic predisposition is an important causal factor of febrile seizures and mesial temporal sclerosis. From recent clinical and molecular genetic studies, it appears that the relationship between febrile seizures and later epilepsy is frequently genetic, and there are several syndrome-specific genes for febrile seizures. SUMMARY: Mesial temporal sclerosis probably has different causes. A number of retrospective studies showed that complex febrile seizures are a causative factor for the later development of mesial temporal sclerosis and temporal lobe epilepsy. However, contradictory results have come from several prospective and retrospective studies. The association between febrile seizures and temporal lobe epilepsy probably results from complex interactions between several genetic and environmental factors.

Atrophy↗

The role of tau (MAPT) in frontotemporal dementia and related tauopathies.

Tau is a multifunctional protein that was originally identified as a microtubule-associated protein. In patients diagnosed with frontotemporal dementia and parkinsonism linked to chromosome 17, mutations in the gene encoding tau (MAPT) have been identified that disrupt the normal binding of tau to tubulin resulting in pathological deposits of hyperphosphorylated tau. Abnormal filamentous tau deposits have been reported as a pathological characteristic in several other neurodegenerative diseases, including frontotemporal dementia, Pick Disease, Alzheimer disease, argyrophilic grain disease, progressive supranuclear palsy, and corticobasal degeneration. In the last five years, extensive research has identified 34 different pathogenic MAPT mutations in 101 families worldwide. In vitro, cell-free and transfected cell studies have provided valuable information on tau dysfunction and transgenic mice carrying human MAPT mutations are being generated to study the influence of MAPT mutations in vivo. This mutation update describes the considerable differences in clinical and pathological presentation of patients with MAPT mutations and summarizes the effect of the different mutations on tau functioning. In addition, the role of tau as a genetic susceptibility factor is discussed, together with the genetic evidence for additional causal genes for tau-positive as well as tau-negative dementia.

Alzheimer Disease↗

Uncovering metabolite-immune interactions in the pathogenesis of psoriatic arthritis: A 2-sample Mendelian randomization study.

PsA is a chronic inflammatory joint condition associated with psoriasis, and its underlying mechanisms are not fully elucidated. Serum metabolites, as direct reflections of metabolic status, may influence disease progression by regulating immune cell function; however, the causal relationships and specific pathways require further investigation. The present investigation utilized a 2-sample bidirectional MR methodology, leveraging extensive pooled GWAS data to thoroughly evaluate the causal relationships between 1440 serum metabolites and PsA. Additionally, mediation MR analysis was performed to explore the possible mediating effects of 731 immune cell characteristics. In the primary analysis, inverse-variance weighted was employed, and this was further supported by various sensitivity analyses to confirm the reliability of the findings. The genetic method to infer causality analysis revealed significant positive causal associations between 10 serum metabolites and PsA risk, with quinolinate levels demonstrating the most significant correlation (OR = 1.56, 95% CI: 1.26-1.93); while 4 metabolites (e.g., citrate levels, OR = 0.74, 95% CI: 0.61-0.89) exhibited protective effects. Regarding immune cells, 6 cellular features (e.g., CD20 on B cells) were positively correlated with disease risk, whereas 5 features (primarily HLA-DR expression on monocyte subsets) showed negative correlations. Mediation analysis identified 3 significant pathways,the percentage of the effect explained by the mediator: N6,N6,N6-trimethyllysine levels mediated via B cells (CD20 on IgD+ CD38br), with a proportion of 33.2%; 1-stearoyl-2-docosahexaenoyl-GPE (18:0/22:6) levels mediated through monocytes (HLA-DR on CD14- CD16-) with a 32.0% proportion; the unknown metabolite X-24736 also mediated 42.1% of the protective effect via the same monocyte phenotype. This study revealed that elevated amino acid-related metabolites and glycerophospholipids significantly increase PsA risk through immune cell effects. These are closely associated with PsA pathogenesis and may serve as potential biomarkers. The novel findings underscore metabolic-immune interactions as targets for biomarkers and therapies in PsA, advancing personalized medicine.

Humans↗

[Genetic markers of individual predisposition to lung cancer].

The investigation concerning the dependence of cancer incidence on genetic HLA-markers and character of dermatoglyphs was carried out. The use of the pattern recognition method for multifactorial estimation of the above markers as well as the elimination of the main non-genetic oncogenic risk factors allowed obtaining the proof of the existence of the genetic predisposition to lung cancer. It was estimated that the character of dermatoglyphic prints is the most adequate marker for the investigated predisposition, and the reliable prediction of the genetic risk of the lung cancer development can be given as based on the joint evaluation of both markers.

Causality↗

Comparing genome-wide significant and chemosensory variants as instruments for dietary patterns in Mendelian randomization.

BACKGROUND: Diet is a modifiable risk factor for cardiometabolic disease, yet establishing causality remains challenging. Mendelian randomization (MR) leverages genetic variants as instrumental variables (IVs) to enable causal inference. METHOD: Using two-sample MR, we assessed the causal effects of four principal component-derived dietary patterns (DPs)-Unhealthy, Healthy, Meat-based, Pescatarian-on cardiometabolic outcomes including body mass index, coronary artery disease, blood lipids, blood pressures, type 2 diabetes, fasting glucose and insulin, and glycated haemoglobin. Two sets of IVs were employed: conventional genome-wide significant variants associated with each DP, filtered for pleiotropy and directionality; and biologically informed variants in chemosensory receptor genes, given the role of taste and smell perception in food choice. RESULTS: Using conventional IVs, the Pescatarian DP was associated with reduced fasting insulin (βIVW = -0.10 pmol/L per SD increase in the Pescatarian DP score, 95% confidence interval -0.15, -0.04; P = 1.19 × 10-3), surviving multiple sensitivity analyses. Associations between the Unhealthy DP and elevated blood pressure and glycated haemoglobin should be interpreted cautiously; one of the two filtered IVs was strongly associated with caffeine intake, limiting the attribution of these findings to the DP itself. Chemosensory Receptor IVs yielded null findings, reflecting insufficient power. CONCLUSION: Evidence for causal effects of DPs on cardiometabolic traits was limited, with the strongest support for a protective effect of the Pescatarian DP on fasting insulin. Chemosensory IVs demonstrated limited utility for DPs, likely reflecting the heterogeneous and complex sensory profiles of overall diets. Future efforts should consider guideline-based dietary indices to facilitate interpretability and translation.

Humans↗

Rat genetics: the next episode.

More than a thousand quantitative trait loci (QTLs) relevant to many aspects of complex human disease have been identified in a wide range of rat inbred lines over the past few decades. With the complete rat genome available, it is now time for the next stage in rat genetic research: the identification and causal confirmation of underlying polymorphisms and genes. Recent developments in single nucleotide polymorphism-based genetic markers and technologies to manipulate the rat genome will undoubtedly be important tools in this next episode.

Animals↗

Genes, environment, and cardiovascular disease.

In this essay, we call to attention what every medical researcher knows about the etiology of cardiovascular disease but most deny, or choose to ignore, when designing, carrying out, and reporting genetic studies. Medical research is entering an era of synthesis that will take advantage of the successes of reductionism over the past decade in defining and describing human genome variations. Meaningful insights into the role of such variation requires a biological model of genome-phenotype relationships that incorporates interactions between subsets of possible genetic and environmental agents as causations in particular contexts indexed by time and space. We make recommendations for what needs to be done to cope with these complexities.

Cardiovascular Diseases↗

Stress, behavior and experimental hypertension.

Over the past twenty-five years, several animal models of human essential hypertension have been produced through the development of inbred strains or lines of laboratory rats. The general availability of laboratory rats with genetically determined increases in arterial blood pressure has stimulated an impressive volume of research in the pathophysiology of experimental hypertension. In contrast, relatively little attention has been devoted to the study of behavioral correlates of experimental hypertension. In this review, I will evaluate the advantages and limitations of studying animal models of essential hypertension. Emphasis will then be placed on the relationship between stressful stimulation and behavioral and physiological responsiveness in two animal models of essential hypertension. Specifically, studies from my laboratory have examined sympathetic nervous system activity and behaviors of rats under basal conditions and following acute or chronic exposure to stressful stimulation. These findings indicate that the spontaneously hypertensive (SHR) strain is excessively responsive behaviorally and physiologically to a variety of stressful stimuli when compared to its Wistar-Kyoto (WKY) normotensive control strain. In contrast, the behavioral and physiological responses of New Zealand genetically hypertensive (GH) and normotensive (N) rats do not differ following acute exposure to stress. Thus, the hyperreactivity of SHR rats to stressful stimulation is not necessarily related to the development of hypertension but may be a valuable marker of the predisposition to develop high blood pressure in rats of the SHR strain. An experimental approach is outlined for examining the causal relationship between a genetically determined physiological or behavioral marker and the development of hypertension.

Adrenal Medulla↗