A bidirectional Mendelian randomization study supports the causal effects of a high basal metabolic rate on colorectal cancer risk

Sex-specific Mendelian randomization phenome-wide association study of basal metabolic rate

Observationally, higher basal metabolic rate (BMR) is associated with metabolism-related disorders, cancer, aging, and mortality. In this Mendelian randomization (MR) phenome-wide association study, using two-sample MR methods, we systematically and comprehensively investigated the health effects of genetically predicted BMR across the phenome sex-specifically. We obtained sex-specific genetic variants strongly (p < 5 × 10- 8) and independently (r2 < 0.001) predicting BMR from the UK Biobank and applied them to over 1,000 phenotypes within the same study. We combined genetic variant-specific Wald estimates using inverse-variance weighting, supplemented by sensitivity analysis. We used a false-discovery rate correction to allow for multiple comparisons as well as multivariable MR adjusted for body mass index and testosterone to investigate the independent effects of BMR on phenotypes with significant univariable associations. We obtained 217/219 genetic variants predicting BMR and applied them to 1,150/1,242 phenotypes in men/women, respectively. BMR was associated with 190/270 phenotypes in univariable analysis and 122/123 phenotypes in multivariable analysis in men/women. Examples of robust associations in multivariable analysis included those with neoplasms, diseases of the circulatory system, and growth and reproductive investment. In conclusion, BMR might affect a wide range of health-related outcomes. The underlying mechanisms and interactions between phenotypes warrant further study, as BMR is modifiable.

Basal metabolic rate mediates the causal relationship between gut microbiota and osteoarthritis: a two-step bidirectional Mendelian randomization study

Background

The relationship between gut microbiota and osteoarthritis (OA) occurrence remains unclear. Existing research needs to clearly understand how basal metabolic rate (BMR) regulates this relationship. Therefore, using a two-step bidirectional Mendelian Randomization approach, our study aims to investigate whether BMR levels mediate the causal relationship between gut microbiota and OA.

Methods

In this study, we examined publicly available summary statistics from Genome-Wide Association Studies (GWAS) to determine the correlation between gut microbiota and OA. The analysis included one primary dataset and two secondary datasets. Initially, a two-step, two-sample, and reverse MR analysis was performed to identify the causal relationship between gut microbiota and OA. Subsequently, a two-step MR analysis revealed that the relationship between microbiota and OA is mediated by BMR. Sensitivity analyses confirmed the robustness of the study results.

Results

In our analysis of the primary dataset, we discovered a positive correlation between three taxa and the outcome of OA, and eight taxa exhibited a negative correlation with the OA outcome. Through comparisons with the secondary dataset and multiple testing corrections, we found a negative association between the class Actinobacteria (OR=0.992886277, p-value = 0.003) and the likelihood of OA occurrence. Notably, knee osteoarthritis (KOA) and hip osteoarthritis (HOA) had a strong negative correlation (OR = 0.927237553/0.892581219). Our analysis suggests that BMR significantly mediates the causal pathway from Actinobacteria to OA, with a mediated effect of 2.59%. Additionally, BMR mediates 3.98% of the impact in the path from the order Bifidobacteriales and the family Bifidobacteriaceae to OA. Besides these findings, our reverse analysis did not indicate any significant effect of OA on gut microbiota or BMR.

Conclusion

Our research results indicate that an increase in the abundance of specific gut microbial taxa is associated with a reduced incidence of OA, and BMR levels mediate this causal relationship. Further large-scale randomized controlled trials are necessary to validate the causal impact of gut microbiota on the risk of OA. This study provides new insights into the potential prevention of OA by modulating the gut microbiota.

The causal relationship of serum uric acid on colorectal cancer: A Mendelian randomization study

Colorectal cancer (CRC) is a significant public health issue owing to its widespread occurrence and substantial morbidity and mortality rates. Recent studies have highlighted serum uric acid (SUA) level as a probable risk factor for CRC; however, the inconsistency in these findings has created doubt. We performed a Mendelian randomization (MR) study utilizing extensive cohort data from the UK BioBank and the NHGRI-EBI Genome-Wide Association Study (GWAS) Catalog to investigate the causal connection between SUA levels and CRC incidence. Our MR study addresses the constraints of earlier studies, including limited sample sizes and inconsistent results. Considering SUA levels as the exposure and CRC as the outcome, the inverse variance-weighted (IVW) approach in MR showed that the odds ratios (ORs) for CRC for each unit increase in SUA were 0.232 (95% confidence interval [CI] of OR 0.094-0.570; P = .001) and 0.551 (95% CI of OR 0.325-0.934; P = .027). Pleiotropic tests and sensitivity analysis confirmed minimal horizontal pleiotropy and the robustness of causality. Our research deepens the understanding of the association between SUA levels and CRC, offering insights into prevention strategies and patient outcomes prediction.

Anthropometric indicators may explain the high incidence of follicular lymphoma in Europeans: Results from a bidirectional two-sample two-step Mendelian randomisation

BACKGROUND

Non-Hodgkin's lymphoma incidence rates vary between European and Asian populations. The reasons remain unclear. This two-sample two-step Mendelian randomisation (MR) study aimed to investigate the causal relationship between anthropometric indicators (AIs) and diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) and the possible mediating role of basal metabolic rate (BMR) in Europe.

METHODS

We used the following AIs as exposures: body mass index (BMI), whole-body fat mass (WBFM), whole-body fat-free mass (WBFFM), waist circumference(WC), hip circumference(HC), standing height (SH), and weight(Wt). DLBCL and FL represented the outcomes, and BMR was a mediator. A two-sample MR analysis was performed to examine the association between AIs and DLBCL and FL onset. We performed reverse-MR analysis to determine whether DLBCL and FL interfered with the AIs. A two-step MR analysis was performed to determine whether BMR mediated the causality.

FINDINGS

WBFFM and SH had causal relationships with FL. A causal association between AIs and DLBCL was not observed. Reverse-MR analysis indicated the causal relationships were not bidirectional. Two-step MR suggested BMR may mediate the causal effect of WBFFM and SH on FL.

CONCLUSIONS

We observed a causal relationship between WBFFM and SH and the onset of FL in Europeans, Which may explain the high incidence of follicular lymphoma in Europeans.

Causal Effects of Basal Metabolic Rate on Cardiovascular Disease: A Bidirectional Mendelian Randomization Study

BACKGROUND

Despite the health effects of basal metabolic rate (BMR), the causal effect of BMR on cardiovascular diseases (CVDs) remains undetermined. To elucidate the causal nature, Mendelian randomization (MR) analyses were performed.

METHODS AND RESULTS

Summary genome-wide association statistics regarding BMR and 5 CVDs were obtained from European databases. A 2-sample bidirectional MR was performed to assess the causal association between BMR and CVDs. The causal effects were estimated using inverse variance weighting. Simultaneously, multiple sensitivity analyses were performed to validate the robustness and reliability of the results. Our results indicated that genetically predicted BMR was significantly positively associated with the risk of heart failure (odds ratio, 1.53 [95% CI, 1.39-1.67]; P<0.001), atrial fibrillation and flutter (odds ratio, 2.12 [95% CI, 1.87-2.40]; P<0.001), and aortic aneurysm (odds ratio, 1.64 [95% CI, 1.41-1.92]; P<0.001). Genetically predicted BMR may not be causally associated with coronary artery disease and ischemic stroke risk. Furthermore, a significant causal effect of CVDs on BMR was not found in the reverse MR analysis. Multivariable MR was applied to further assess the direct effect of BMR on CVDs. Multivariable MR indicated that a high level of BMR still increased the risk of heart failure and atrial fibrillation and flutter after adjustment independent of possible confounders. However, the P value of aortic aneurysm was not significant.

CONCLUSIONS

The present study provides robust evidence that genetically predicted BMR is independently causally associated with heart failure and atrial fibrillation and flutter but not vice versa. These findings have implications for the prevention and treatment of CVDs in clinical practice.

Genetically predicted basal metabolic rate and venous thromboembolism risk: a Mendelian randomization study

Background

Basal metabolic rate (BMR) is the minimum amount of energy needed by the body to carry out essential physiological functions. The goal of this study was to evaluate whether BMR causally influences venous thromboembolism (VTE) and its subtypes in European individuals.

Methods

A two-sample Mendelian randomization (MR) was performed. Within a genome-wide association study (GWAS) involving 454,874 people, genetic variants were chosen as instrumental variables based on their significant associations (p < 5 × 10-8) with BMR and their limited linkage disequilibrium (r2 < 0.001). The FinnGen project served as sources for summary statistics of VTE, encompassing different subtypes.

Results

Using the multiplicative random-effect inverse variance weighted method, our investigation revealed that one standard deviation higher BMR was associated with VTE (odds ratio [OR] = 1.684, 95% confidence interval [CI]: 1.465-1.936, p = 2.339 × 10-13), PE (OR = 1.824, 95% CI: 1.512-2.200, p = 3.399 × 10-10), and DVT of lower extremities (OR = 1.887, 95% CI: 1.562-2.280, p = 4.778 × 10-11). The consistency of these associations was observed in sensitivity analyses using various MR techniques like Mendelian randomization pleiotropy residual sum and outlier, MR-Egger, weighted median, and contamination mixture method. In addition, multivariable MR revealed direct effects of BMR on VTE and its subtypes when taking body mass index and current tobacco smoking into account.

Conclusion

Higher BMR may increase the risk of VTE and its subtypes including PE and DVT of lower extremities.

The association between basal metabolic rate and osteoarthritis: a Mendelian randomization study

BACKGROUND

The role of the basal metabolic rate (BMR) in osteoarthritis (OA) remains unclear, as previous retrospective studies have produced inconsistent results. Therefore, we performed a Mendelian randomization (MR) study to systematically investigate the causal relationship between the BMR and OA.

METHODS

Single-nucleotide polymorphism (SNP) data related to BMR and OA were collected in a genome-wide association study. Using OA as the outcome variable and BMR as the exposure factor, SNPs with strong correlation with the BMR as the tool variable were screened. The correlation between the BMR and OA risk was evaluated using the inverse-variance weighted method, and heterogeneity and pleiotropy were evaluated using a sensitivity analysis.

RESULTS

There was a potential causal relationship between the BMR and OA risk (odds ratio [OR], 1.014; 95% confidence interval [CI], 1.008-1.020; P = 2.29e - 6). A causal relationship was also revealed between the BMR and knee OA (OR, 1.876; 95% CI, 1.677-2.098; P = 2.98e - 28) and hip OA (OR, 1.475; 95% CI, 1.290-1.686; P = 1.26e - 8). Sensitivity analysis confirmed the robustness of these results.

CONCLUSION

Here, we identified a latent causal relationship between the BMR and the risk of OA. These results suggest that the risk of OA in the hip or knee joint may be reduced by controlling the BMR.