Birth weight, childhood obesity, adulthood obesity and body composition, and gastrointestinal diseases: a Mendelian randomization study

Life-course obesity and heart failure: a two-sample Mendelian randomization study

Heart failure is a multifaceted clinical syndrome, with obesity identified as a significant modifiable risk factor. This study employed a two-sample Mendelian randomization (MR) design, incorporating obesity data across life stages, to elucidate the causal link between obesity and heart failure. Data on heart failure from the 2023 Finngen database and genetic predictors of obesity from the IEU OpenGWAS project were analyzed using the IVW method, MR-Egger regression, weighted median, simple mode, weighted mode, and scatter plots. Heterogeneity was assessed with Cochran's Q test, and horizontal pleiotropy with MR-Egger intercept test. Sensitivity to single-nucleotide polymorphisms (SNPs) was tested via leave-one-out analysis, and funnel plots were utilized for visual inspection of horizontal pleiotropy. Statistical powers were also calculated. The MR analysis findings indicate a significant relationship between birth weight and the likelihood of developing heart failure (Odds Ratio [OR] 1.134, 95% Confidence Interval [CI] 1.033-1.245, P = 0.008). In addition, a heightened childhood BMI was found to be a significant predictor of heart failure risk (OR 1.307, 95% CI 1.144-1.494, P = 8.51E-05), as was childhood obesity (OR 1.123, 95% CI 1.074-1.173, P = 2.37E-07). Furthermore, adult BMI sex-combined exhibited a strong correlation with the risk of heart failure (OR 2.365, 95% CI 2.128-2.629, P = 1.91E-57). Sensitivity analyses provided further support for the reliability of these results, with no significant indication of horizontal pleiotropy observed. This study shows that obesity, including childhood obesity, is linked to a higher risk of heart failure. These findings highlight the urgent need for early weight management interventions in public health and clinical settings to reduce heart failure rates.

Determinants of childhood obesity in China

Over the past four decades, China has witnessed an important nutritional transition, characterised by a heightened overnutrition burden among children. The country now has the largest population of children with obesity globally. In this paper, we review the epidemiology of childhood obesity in China, its determinants, and risk factors, with a particular focus on school-aged children. Evidence unveils substantial variations across age, gender, and region. We describe multilevel obesogenic determinants, including macro-level social, cultural, and environmental factors; meso-level factors related to schools and communities; and micro-level factors tied to families and individuals from the perinatal-infant stage to childhood and adolescence. The primary drivers of childhood obesity appear to be rooted in the broader macro-level social, economic, and technological environment; obesogenic factors, which have affected school, community, and family environments; and accelerated unhealthy behaviour uptake. Identifying and characterising the catalysts behind the rise in childhood obesity in China is imperative for the development of scalable, effective, and tailored prevention, control, and intervention strategies.

Childhood obesity and risk of inflammatory bowel disease in adulthood: A Mendelian randomization study

It is well-known that childhood obesity is associated with various adult gastrointestinal diseases, inflammatory bowel disease (IBD) being no exception. However, previous epidemiological observational studies, while reporting a correlation between the 2, have left the question of a causal relationship inconclusive. This study aims to use a 2-sample Mendelian randomization (MR) analysis to assess the causal relationship between childhood obesity and IBD as well as its subtypes (ulcerative colitis [UC] and Crohn disease [CD]). Data on childhood obesity, IBD, and its subtypes (UC and CD) were sourced from IEU OpenGWAS (https://gwas.mrcieu.ac.uk/datasets/ieu-a-1096/) and IIBDGC (https://www.ibdgenetics.org/). The data were analyzed using the inverse variance weighted (IVW), MR-Egger, weighted median, simple mode, and weighted mode methods. The MR analysis indicates no causal relationship between childhood obesity and IBD or its subtypes (UC and CD). The consistency of the results across the IVW, MR-Egger, weighted median, simple mode, and weighted mode methods suggests the reliability of the findings. We found that childhood obesity is not causally related to IBD or its subtypes (UC and CD). This differs from prior studies. The observed discrepancies may be due to common biological or environmental confounding factors.

Birth weight and risk of cerebral aneurysm: A multivariable Mendelian randomization study

BACKGROUND

Birth weight has been linked with various health outcomes. The association between birth weight and cerebral aneurysm remains unknown.

METHODS

The two-sample Mendelian randomization (MR) approach was used to evaluate the causal effect of birth weight on cerebral aneurysm based on genome-wide association studies (GWAS), comprising 261,932 UKB participants for birth weight and 204,060 FinnGen participants for cerebral aneurysm. The inverse variance weighted (IVW) method was used as the primary method. Alternative methods were used for comparison. Sensitivity analysis was conducted to evaluate the robustness of the results. Multivariable MR (MVMR) was further conducted to evaluate the direct effect of the birth weight on cerebral aneurysm.

RESULTS

The IVW detected a causal association between higher birth weight and increased risk of cerebral aneurysm (OR = 0.521, 95% CI = 0.356 ∼ 0.763, P = 7.88 × 10-4), which was supported by alternative MR models. Sensitivity analysis did not find any evidence of heterogeneity or pleiotropy. MVMR further identified a direct effect of birth weight on cerebral aneurysm, independent of obesity-related traits or smoking.

CONCLUSION

This MR study found evidence of the association between birth weight and cerebral aneurysm, providing novel insight into the etiology of cerebral aneurysm, indicating the promising role of birth weight as a marker for screening populations at higher risk of cerebral aneurysm.

Birthweight influences liver structure, function and disease risk: Evidence of a causal association

AIM

Low birthweight is an issue during pregnancy associated with an increased risk of developing liver disease later in life. Previous Mendelian randomisation (MR) studies which explored this issue have not isolated the direct impact of the foetus on birthweight. In the present study, MR was used to assess whether direct foetal effects on birthweight were causally associated with liver structure, function and disease risk independent of intrauterine effects.

MATERIALS AND METHODS

We extracted single nucleotide polymorphisms (SNPs) from genome-wide association studies (GWAS) about direct foetal-affected birthweight (321 223 cases) to conduct univariable and multivariable MR analyses to explore the relationships between birthweight and 4 liver structure measures, 9 liver function measures and 18 liver diseases. A two-step MR analysis was used to further assess and quantify the mediating effects of the mediators.

RESULTS

When isolating direct foetal effects, genetically predicted lower birthweight was associated with a higher risk of non-alcoholic fatty liver disease (NAFLD) (odds ratios [OR], 95% confidence interval [CI]: 1.61, 1.29-2.02, p < 0.001), higher magnetic resonance imaging [MRI] proton density fat fraction (PDFF) and higher serum gamma glutamyltransferase (GGT). Two-step MR identified two candidate mediators that partially mediate the direct foetal effect of lower birthweight on NAFLD, including fasting insulin (proportion mediated: 22.29%) and triglycerides (6.50%).

CONCLUSIONS

Our MR analysis reveals a direct causal association between lower birthweight and liver MRI PDFF, as well as the development of NAFLD, which persisted even after accounting for the potential influence of maternal factors. In addition, we identified fasting insulin and triglycerides as mediators linking birthweight and hepatic outcomes, providing insights for early clinical interventions.

Causal Relationship Between Gastroesophageal Reflux Disease and the Risk of Chronic Rhinosinusitis: Insights from Multivariable and Mediation Mendelian Randomization Analysis

Background: Previous studies have shown an association between chronic rhinosinusitis (CRS) and gastroesophageal reflux disease (GERD). However, the findings of these studies are controversial, and evaluating this association could help in the treatment of CRS. Thus, we aimed to clarify the relationship between GERD and CRS. Methods: We conducted a Mendelian randomization (MR) study. Pooled data on CRS, GERD, and their associated risk factors were extracted from large genome-wide association studies. Independent single-nucleotide polymorphisms were rigorously screened as instrumental variables. Causal associations between GERD and CRS were assessed, and mediation analyses were performed using multivariate and 2-step MR. Asthma served as a mediator because of its association with both CRS and GERD. Sensitivity tests were also performed. Results: MR analysis showed that genetically predicted GERD was associated with an increased risk of CRS (P < .001). Multivariate MR analysis showed that the effect of GERD on CRS was relatively independent. Mediation analysis showed that asthma mediated the association with a mediation effect of 21.07% (95% CI, 2.70%-40.18%). Sensitivity analyses did not reveal any significant effects of pleiotropy and heterogeneity. Conclusions: We found a causal relationship between genetically predicted GERD and an increase in the risk of CRS. As a mediator, asthma contributed to the effect of GERD on CRS. This study provides high-quality causal evidence for the prevention of CRS.

Unravel the distinct effects of adiposity at different life stages on COVID-19 susceptibility and severity: A life-course Mendelian randomization study

Childhood obesity is widely recognized as a risk factor for numerous health conditions, particularly cardiovascular disease. However, it remains unclear whether childhood adiposity directly affects the risk of COVID-19 in later life. We aimed to investigate the causal effects of early life adiposity on COVID-19 susceptibility and severity. We used genetic instruments from large-scale genome-wide association studies to examine the relationships between birth weight, childhood and adulthood adiposity indicators (including body mass index [BMI], obesity, and body size), and COVID-19 outcomes. Univariable and multivariable Mendelian randomization (MR) analyses were used to obtain the causal estimates. Univariable MR analyses found that childhood BMI and obesity were positively associated with COVID-19 risk and severity in adulthood, however, the significant associations were attenuated to null after further adjusting for adulthood adiposity indicators in multivariable MR analyses. In contrast, our analysis revealed strong evidence of a genetically predicted effect of childhood obesity on COVID-19 hospitalization (OR 1.08, 95% CI: 1.01-1.15, p = 2.12E-2), which remained robust even after adjusting for adulthood obesity and potential lifestyle confounders. Our results highlight the importance of promoting healthy weight management throughout life to reduce the risk of COVID-19.

Body shape from birth to adulthood is associated with skeletal development: A Mendelian randomization study

BACKGROUND

Observational studies have shown that childhood obesity is associated with adult bone health but yield inconsistent results. We aimed to explore the potential causal association between body shape and skeletal development.

METHODS

We used two-sample Mendelian randomization (MR) to estimate causal relationships between body shape from birth to adulthood and skeletal phenotypes, with exposures including placental weight, birth weight, childhood obesity, BMI, lean mass, fat mass, waist circumference, and hip circumference. Independent genetic instruments associated with the exposures at the genome-wide significance level (P < 5 × 10-8) were selected from corresponding large-scale genome-wide association studies. The inverse-variance weighted analysis was chosen as the primary method, and complementary MR analyses included the weighted median, MR-Egger, weighted mode, and simple mode.

RESULTS

The MR analysis shows strong evidence that childhood (β = -1.29 × 10-3, P = 8.61 × 10-5) and adulthood BMI (β = -1.28 × 10-3, P = 1.45 × 10-10) were associated with humerus length. Tibiofemoral angle was negatively associated with childhood BMI (β = -3.60 × 10-1, P = 3.00 × 10-5) and adolescent BMI (β = -3.62 × 10-1, P = 2.68 × 10-3). In addition, genetically predicted levels of appendicular lean mass (β = 1.16 × 10-3, P = 1.49 × 10-13), whole body fat mass (β = 1.66 × 10-3, P = 1.35 × 10-9), waist circumference (β = 1.72 × 10-3, P = 6.93 × 10-8) and hip circumference (β =1.28 × 10-3, P = 4.34 × 10-6) were all associated with tibia length. However, we found no causal association between placental weight, birth weight and bone length/width.

CONCLUSIONS

This large-scale MR analysis explores changes in growth patterns in the length/width of major bone sites, highlighting the important role of childhood body shape in bone development and providing insights into factors that may drive bone maturation.

Association of body composition indicators with colorectal cancer: a hospital-based case-control study

PURPOSE

Colorectal cancer (CRC) is a common malignancy that affects adults worldwide, causing a high disease burden. Few studies have examined the relationship between body composition (BC) measures and the prevalence of CRC. Our purpose was to investigate the relationship between pertinent BC indicators and CRC.

METHODS

Bioelectrical impedance analysis, laboratory test results, face-to-face questionnaire investigation, and nutritional risk assessment (Nutritional Risk Screening 2002 and Patient-Generated Subjective Global Assessment) were used in this case-control study. Bioelectrical impedance analysis in the case group was performed prior to antitumor therapy/surgery.

RESULTS

From June 2018 to January 2019, a total of 303 cases and 286 controls were included. The results showed that low body fat percentage (BFP) and high visceral adiposity index (VAI) groups had a higher risk of developing CRC in comparison to the normal BFP and normal VAI groups. The risk of CRC decreased with the increase of BFP. The group with a normal BC had a lower risk of developing CRC compared to those with a greater VAI and a lower BFP, as indicated by the results of the pairwise and total combinations of VAI, fat-free mass index (FFMI), and BFP. Additionally, FFMI and VAI had positive correlations with prealbumin, serum albumin, and nutritional risk scores.

CONCLUSION

Low BFP and high VAI are associated with higher CRC risk. FFMI and VAI are positively correlated with prealbumin, serum albumin, and nutritional risk scores in CRC patients.

Mendelian randomisation analysis for intestinal disease: achievement and future

Intestinal disease is a group of complex digestive system diseases imposing a significant burden globally. Identifying the risk factors and potential complications of intestinal disease is important for its prevention and treatment. However, traditional observational clinical studies are limited by confounding factors and reverse causation, making causal inference challenging. Mendelian randomisation (MR) method has been developed to effectively mitigate these constraints and assess the causal relationships. This review briefly introduces the MR method, summarises MR research on intestinal disease and delineates the prospective avenues for future research. Conventional risk factors, such as lifestyle behaviours (eg, physical activity, smoking and alcohol consumption), nutrients (eg, selenium), obesity markers (eg, body mass index and waist-to-hip ratio) and inflammatory biomarkers, have been validated in MR studies. Multiomics MR studies are becoming novel hotspots, which provide a theoretical foundation for the exploration of pathogenesis and the investigation of new drug targets. However, most of the recent studies are based on European individuals, and thus it is necessary to replicate the results in other ancestries. Moreover, triangulation integrating MR and other epidemiology methods is suggested as a validated paradigm for causal inference in future MR studies.

Multidisciplinary combined treatment based on bariatric surgery for metabolic syndrome: a review article

As a chronic, multifactorial disease, obesity is associated with a global social and economic burden. This condition significantly affects normal daily life and healthy social interactions, and shortens the life expectancy of patients. Compared with traditional weight-loss methods, the emergence of bariatric surgery has effectively improved the management of obesity. Furthermore, bariatric surgery can also inhibit the progression of multiple metabolic diseases. Despite its potential advantages, bariatric surgery cannot completely eliminate the possibility of weight regain and inadequate weight loss following the procedure. For super-obese patients, bariatric surgery still remains a surgical risk. In addition, the psychological problems and poor eating habits of obese patients also affect the weight loss effect and daily life. Thus, various adjuvant therapies involving multiple disciplines have attracted people's attention. Recently, it has been recognized that the combination of multiple interventions based on bariatric surgery is more advantageous than a single intervention in alleviating the complex and diverse metabolic diseases associated with obesity. The combined therapy considerably enhances the long-term efficacy of bariatric surgery and plays a positive role in the mental health and social lives of patients. In this article, the authors review this multidisciplinary combination therapy to enhance the current understanding of the treatment of obesity.

Independent associations of education, intelligence, and cognition with gastrointestinal diseases and the mediating effects of risk factors: a Mendelian randomization study

Background

Education, intelligence and cognition affect occupational performance and socioeconomic status and may influence virous diseases development. However, the impact of these factors on gastrointestinal diseases and their mediating risk factors remains unclear.

Methods

We utilized genome-wide association studies from European ancestry populations to perform two-sample Mendelian randomization analyses, aiming to estimate genetic instruments associated with education, intelligence, or cognition in relation to 24 gastrointestinal diseases Subsequently, we evaluated 14 potential mediators of this association and calculated the corresponding mediated proportions through two-step Mendelian randomization analyses.

Result

As the dominant factor in gastrointestinal diseases, education had a statistically significant association with 2 gastrointestinal diseases (acute pancreatitis, gastroesophageal reflux) and a suggestive association with 6 diseases (cirrhosis, alcoholic liver disease, cholecystitis, cholelithiasis, chronic gastritis and gastric ulcer). Of the 14 mediators, smoking and adiposity traits played a major role in mediating the effects.

Conclusion

The study demonstrated the causal, independent impact of education on specific gastrointestinal diseases. Smoking and adiposity traits emerged as primary mediators, illuminating potential avenues for targeted interventions for prevention of them.

Older age of celiac disease diagnosis and risk of autoimmune disease: A nationwide matched case-control study

OBJECTIVES

Celiac disease (CeD) has been linked to an increased risk of other autoimmune diseases, yet the impact of delayed CeD diagnosis on risk of developing additional autoimmune diseases remains uncertain. We investigated this through a nationwide matched case-control study.

METHODS

Using the ESPRESSO cohort with histophatology data from Sweden's 28 pathology departments, we assessed 46,575 biopsy-confirmed CeD cases from 1964 to 2017. We extracted 225,295 matched controls without histopathology information from the Swedish Total Population Register. Autoimmune disease was defined through diagnostic codes in the National Patient Register. Through conditional logistic regression we estimated odds ratio (OR) of autoimmune disease up until CeD diagnosis/matching date comparing CeD cases to controls across different age strata.

RESULTS

A total of 3059 (6.6 %) CeD patients and 4076 (1.8 %) controls had earlier autoimmune disease. The overall OR for autoimmune disease in CeD was 3.50 (95%CI 3.32-3.70). The risk of autoimmune disease did not escalate with increasing age at CeD diagnosis. Compared with controls, the OR of autoimmune disease in CeD patients was 7.70 (95%CI 4.71-12.57) in those diagnosed with CeD in 0-4 years, 19.02 (95%CI 13.80-26.23) in 5-9 years, 6.18 (95%CI 5.14-7.44) in 10-14 years, 4.80 (95%CI 3.97-5.79) in 15-19 years, 4.24 (95%CI 3.55-5.07) in 20-29 years, 4.65 (95%CI 3.93-5.51) in 30-39 years, 3.67 (95%CI 3.30-4.09) in 40-59 years, and 1.67 (95%CI 1.50-1.85) in ≥60 years.

CONCLUSIONS

This study revealed an increased risk of autoimmune disease among CeD patients compared with controls. However, older age at CeD diagnosis did not seem to escalate the risk of autoimmune diseases.