Mendelian Randomization: A Powerful Tool to Illuminate Pathophysiologic Mechanisms

Assessing the causal relationship between obesity and ankylosing spondylitis: A two-sample Mendelian randomization study

This study aims to explore the potential causal relationship between obesity and ankylosing spondylitis (AS) using the Mendelian randomization (MR) approach. Data were derived from a comprehensive genome-wide association study dataset. Genetic loci that demonstrated significant, independent associations with both obesity and AS in populations of European ancestry were selected as instrumental variables. Multiple MR analyses, including MR-Egger, weighted median, and inverse variance weighting, were employed to assess the causal impact of obesity on AS risk. To ensure reliability, heterogeneity, and multiplicity tests were conducted, and the robustness of the findings was evaluated through sensitivity analyses using the "leave-one-out" method. The inverse variance weighting analysis revealed an odds ratio (OR) of 0.95 with a 95% confidence interval of 0.76 to 1.19 and a P value of .653. These results indicated no significant causal link between obesity and AS development. Additionally, the heterogeneity and multiplicity tests showed no significant findings, while sensitivity analyses reinforced the consistency and robustness of the conclusions. This research did not find evidence of a causal relationship between obesity and the development of AS based on two-sample MR analysis and genetic data evaluation. However, the current study's limitations, including sample size and study design, highlight the need for future research with larger cohorts to further explore the intricate relationship between obesity and AS.

Investigating the causal impact of body mass index on meniscus injuries: A 2-sample Mendelian randomization study

The aim of this study was to explore the possible causal association between body mass index (BMI) and meniscal injuries using Mendelian randomization (MR), a genetic research method. Relying on pooled data from a large genome-wide association study, we carefully selected a set of genetic variants as instrumental variables that were significantly associated with BMI and meniscal injuries and were independently distributed in populations of European origin. The potential impact of BMI on meniscal injuries was systematically assessed by implementing multiple MR analysis strategies including MR-Egger, weighted median and inverse variance weighting. In addition, heterogeneity and multiple validity tests were introduced in the study, together with the "leave-one-out" sensitivity analysis to ensure the robustness and reliability of the results. Inverse variance weighting analysis revealed a significant positive causal association between BMI and meniscus injury, as shown by the ratio (OR) and its 95% confidence interval of 1.46 (1.22-1.75), with a P-value of <.001. Further tests did not reveal significant heterogeneity and pleiotropy, and the results of the sensitivity analyses supported the robustness of the study findings. Combined with the use of 2-sample MR analysis, this study strongly confirms that BMI is an independent risk factor for meniscal injuries, and this finding provides a new genetic perspective for meniscal injury prevention and intervention.

Body mass index and risk of lumbar spondylolisthesis: An observational study based on two-sample Mendelian randomization analysis

This study aims to investigate the potential causal relationship between body mass index (BMI) and lumbar spondylolisthesis through the application of Mendelian randomization (MR) analysis. We utilized comprehensive data derived from large-scale genome-wide association studies to examine the association between BMI and lumbar spondylolisthesis in populations of European ancestry. Independent genetic variants with significant correlations to BMI and lumbar spondylolisthesis were selected as instrumental variables to ensure methodological rigor. To evaluate the causal impact of BMI on the risk of developing lumbar spondylolisthesis, 3 distinct MR approaches were employed: MR-Egger regression, Weighted Median analysis, and inverse variance weighted estimation. Robustness and consistency of the findings were assessed through heterogeneity testing, multiplicity analysis, and a leave-one-out sensitivity evaluation to confirm the stability of the results. The inverse variance weighted analysis revealed a significant positive association between BMI and lumbar spondylolisthesis risk, with an odds ratio of 1.66 and a 95% confidence interval of 1.20 to 2.29 (P = .002). This finding indicates that individuals with higher BMI are more predisposed to developing lumbar spondylolisthesis. Complementary results from heterogeneity and multiplicity assessments demonstrated no evidence of significant heterogeneity or horizontal pleiotropy, reinforcing the reliability of the findings. Furthermore, the leave-one-out sensitivity analysis confirmed the stability and robustness of the results, providing additional validation of the causal relationship. This investigation offers valuable insights by leveraging two-sample Mendelian randomization analysis to explore the causal link between BMI and lumbar spondylolisthesis. The evidence strongly suggests that elevated BMI contributes significantly to the risk of lumbar spine slippage. These findings highlight the importance of weight management as a preventive strategy for lumbar spine disorders. Promoting healthy BMI levels may serve as a critical intervention to mitigate the risk of lumbar spondylolisthesis, emphasizing the necessity for targeted public health initiatives focused on weight control to enhance spinal health and overall well-being.

Causal relationship between smoking and spinal stenosis: Two-sample Mendelian randomization

OBJECTIVE

Currently, the number of patients with spinal stenosis is increasing, and most of the patients are found to have a history of smoking in the clinic. In this study, we used the Mendelian randomization (MR) method to investigate the causal relationship between smoking and spinal stenosis.

METHODS

Genetic loci independently associated with smoking and spinal stenosis in people of European ancestry were selected as instrumental variables using pooled data from large-scale genome-wide association studies (GWAS). Three MR analyses, MR-Egger, Weighted median and inverse variance weighting (IVW), were used to investigate the causal relationship between smoking and spinal stenosis. The results were tested for robustness by heterogeneity and multiplicity tests, and sensitivity analyses were performed using the "leave-one-out" method.

RESULTS

The IVW results showed an OR (95% CI) of 2.40 (0.31-18.71), P = .403, indicating that there was no causal relationship between smoking and spinal stenosis. And no heterogeneity and multiplicity were found by the test and sensitivity analysis also showed robust results.

CONCLUSION

In this study, genetic data were analyzed and explored using 2-sample MR analysis, and the results showed that there is a causal relationship between smoking and the occurrence of spinal stenosis, and more studies need to be included.

Causal relationship between multiple sclerosis and spinal stenosis: Two-sample Mendelian randomization

To investigate the causal relationship between multiple sclerosis and spinal stenosis using Mendelian randomization (MR). Genetic loci independently associated with multiple sclerosis and spinal stenosis in people of European origin were selected as instrumental variables using pooled data from genome wide association studies (GWAS). Three MR analyses, MR-Egger, Weighted median and inverse variance weighting (IVW), were used to investigate the causal relationship between multiple sclerosis and spinal stenosis. Heterogeneity and multiplicity tests were performed, and sensitivity analyses were performed using the "leave-one-out" method to explore the robustness of the results. The IVW results showed an OR (95% CI) of 1.05 (1.01-1.08), P = .016, indicating a causal relationship between MS and spinal stenosis. And no heterogeneity and multiplicity were found by the test, and sensitivity analysis also showed robust results. In this study, genetic data were analyzed and explored using 2-sample MR analysis, and the results showed a causal relationship between multiple sclerosis and the occurrence of spinal stenosis.

Causal relationship between rheumatoid arthritis and ankylosing spondylitis: Two-sample Mendelian randomization

To investigate the causal relationship between rheumatoid arthritis (RA) and ankylosing spondylitis using Mendelian randomization (MR). Genetic loci independently associated with RA and ankylosing spondylitis in people of European origin were selected as instrumental variables using pooled data from large-scale genome-wide association studies. Three MR analyses, MR-Egger, weighted median, and inverse variance weighting, were used to investigate the causal relationship between RA and ankylosing spondylitis. Heterogeneity and multiplicity tests were used, and a sensitivity test using the "leave-one-out" method was used to explore the robustness of the results. The inverse variance weighting results showed an OR (95 % CI) of 1.25 (1.11-1.41), P < .001, indicating a causal relationship between RA and ankylosing spondylitis. And no heterogeneity and pleiotropy were found by the test and sensitivity analysis also showed robust results. The present study was conducted to analyze and explore the genetic data using two-sample MR analysis and the results showed that there is a causal relationship between RA and the occurrence of ankylosing spondylitis.

Causal relationship between dried fruit intake and meniscal injuries: Two-sample Mendelian randomization

To investigate the causal relationship between dried fruit intake and meniscal injuries using Mendelian randomization (MR). Data were pooled from large-scale genome wide association studies (GWAS), and genetic loci independently associated with dry fruit intake and meniscal injuries in populations of European origin were selected as instrumental variables. Three MR analyses, inverse variance weighting (IVW), weighted median (WME) and MR-Egger, were used to investigate the causal relationship between dried fruit intake and meniscal injuries. The results were tested for robustness by heterogeneity and multiplicity tests, and sensitivity analyses were performed using the "leave-one-out" method. The IVW results showed an OR (95 % CI) of 0.47 (0.28-0.78), P = .003, indicating a causal relationship between dried fruit intake and meniscus injury. And no heterogeneity and multiplicity were found by the test and sensitivity analysis also showed robust results. The present study used a 2-sample MR analysis, and by analyzing and exploring the genetic data, the study showed that too little intake of dry fruits is a risk factor for meniscal injuries.

Causal relationship between obesity and meniscal injuries: Two-sample Mendelian randomization

To investigate the causal relationship between obesity and meniscal injuries using Mendelian randomization (MR). Genetic loci independently associated with obesity and meniscal injuries in people of European origin were selected as instrumental variables using pooled data from genome-wide association studies. Three MR analyses, MR-Egger, weighted median and inverse variance weighting, were used to investigate the causal relationship between obesity and meniscal injuries. The results were tested for robustness by heterogeneity and multiplicity tests, and sensitivity analyses were performed using the "leave-one-out" method. The inverse variance weighting results showed an OR (95% CI) of 1.13 (1.04-1.22), P = .003, indicating a causal relationship between obesity and the occurrence of meniscal injuries. And no heterogeneity and multiplicity were found by the test and sensitivity analysis also showed robust results. In this study, genetic data were analyzed and explored using 2-sample MR analysis, and the results showed that obesity is a risk factor for meniscal injuries.

Causal relationship between dried fruit intake and frozen shoulder: Two-sample Mendelian randomization

To investigate the causal relationship between dried fruit intake and frozen shoulder using Mendelian randomization (MR). Genome wide association studies were conducted to pool data and select genetic loci independently associated with dried fruit intake and frozen shoulder in people of European ancestry as instrumental variables. Three MR analyses, inverse variance weighting, weighted median and MR-Egger, were used to investigate the causal relationship between dried fruit intake and frozen shoulder. Heterogeneity and multiplicity tests were used, and sensitivity analyses were conducted using the leave-one-out method to explore the robustness of the results. The inverse variance weighting results showed an OR (95 % CI) of 0.52 (0.34-0.80), P = .003, suggesting that there is a causal relationship between dried fruit intake and frozen shoulder. And no heterogeneity and multiplicity were found by the test and sensitivity analysis also showed robust results. The present study used a two-sample MR analysis, and by analyzing and exploring the genetic data, the study showed that too little intake of dry fruits is a risk factor for developing frozen shoulder.

Causal relationship between ADHD and frozen shoulder: Two-sample Mendelian randomization

To investigate the causal relationship between attention deficit and hyperactivity disorder (ADHD) and frozen shoulder using Mendelian randomization (MR). Data were pooled from large-scale genome wide association studies, and genetic loci that were independent of each other and associated with ADHD and frozen shoulder in people of European ancestry were selected as instrumental variables. Three MR analyses, inverse variance weighting, weighted median and MR-Egger, were used to investigate the causal relationship between ADHD and frozen shoulder. Heterogeneity and multiplicity tests were used, and sensitivity analyses were performed using the "leave-one-out" method to explore the robustness of the results. The inverse variance weighting results showed an OR (95 % CI) of 1.12 (1.00-1.25), P = .046, indicating a causal relationship between ADHD and frozen shoulder. And no heterogeneity and multiplicity were found by the test and sensitivity analysis also showed robust results. The present study used a two-sample MR analysis, and by analyzing and exploring the genetic data, the study showed that ADHD is a risk factor for developing frozen shoulder, and patients with ADHD are more likely to suffer from frozen shoulder.

The causal relationship between ever smoked and frozen shoulder: A two-sample Mendelian randomization

To investigate the causal relationship between ever smoked and frozen shoulder using a Mendelian randomization (MR) approach. Pooled data from a large-scale genome-wide association study were used. Genetic loci that were independent of each other and associated with ever smoked and frozen shoulder in populations of European ancestry were selected as instrumental variables. Inverse variance weighting was used as the primary analysis method. Weighted median and MR-Egger were used as complementary analysis methods to assess causal effects. To explore the causal relationship between ever smoked and frozen shoulder. Sensitivity test analysis was performed using heterogeneity test, multiple validity test, and leave-one-out analysis to explore the robustness of the results. Inverse variance weighting results of ever smoked showed an OR = 2.49, 95% CI = 1.05-5.91, P = .038, indicating that ever smoked is a risk factor for a frozen shoulder. And the test revealed no heterogeneity and pleiotropy, and the sensitivity analysis also showed robust results. This study used two-sample MR analysis to analyze and explore the genetic data, and the results showed a higher prevalence of frozen shoulder in patients with ever smoked, suggesting that active control of ever smoked may reduce the occurrence of frozen shoulder.

The causal relationship between breast cancer and frozen shoulder: A two-sample Mendelian randomization

To investigate the causal relationship between breast cancer and frozen shoulder using a Mendelian randomization (MR) approach. Pooled data from a large-scale genome-wide association study were used. Genetic loci that were independent of each other and associated with breast cancer and frozen shoulder in populations of European ancestry were selected as instrumental variables. Inverse variance weighting was used as the primary analysis method. Weighted median (WME) and MR-Egger were used as complementary analysis methods to assess causal effects. To explore the causal relationship between breast cancer and frozen shoulder. Sensitivity test analysis was performed using heterogeneity test, multiple validity test, and leave-one-out analysis to explore the robustness of the results. Inverse variance weighting results showed an OR (95% CI) of 1.02 (1.00-1.04), P = .048, indicating that breast cancer is a risk factor for a frozen shoulder. And the test revealed no heterogeneity and pleiotropy, and the sensitivity analysis also showed robust results. In this study, genetic data were analyzed and explored using two-sample MR analysis, and the results showed that the incidence of frozen shoulder was higher in breast cancer patients, suggesting that screening for frozen shoulder in breast cancer patients should be increased.

The causal relationship between depression and frozen shoulder: A two-sample Mendelian randomization

To investigate the causal relationship between depression and frozen shoulder using a Mendelian randomization (MR) approach. Pooled data from a large-scale genome-wide association study were used. Genetic loci that were independent of each other and associated with depression and frozen shoulder in populations of European ancestry were selected as instrumental variables. Inverse variance weighting was used as the primary analysis method. Weighted median and MR-Egger were used as complementary analysis methods to assess causal effects. To explore the causal relationship between depression and frozen shoulder. Sensitivity test analysis was performed using heterogeneity test, multiple validity test, and leave-one-out analysis to explore the robustness of the results. Inverse variance weighting results showed an odds ratio (95% confidence interval) of 1.18 (0.91-1.53), P = .204, indicating that depression was not causally related to the development of frozen shoulder. And the test revealed no heterogeneity and pleiotropy, and the sensitivity analysis also showed robust results. In this study, genetic data were analyzed and explored using a two-sample MR analysis, and the results showed no causal relationship between depression and the occurrence of frozen shoulder, requiring the inclusion of a larger sample for the study.

The causal relationship between hypothyroidism and frozen shoulder: A two-sample Mendelian randomization

To investigate the causal relationship between hypothyroidism and frozen shoulder using a Mendelian randomization (MR) approach. Pooled data from a large-scale genome-wide association study (GWAS) were used. Genetic loci that were independent of each other and associated with hypothyroidism and frozen shoulder in populations of European ancestry were selected as instrumental variables. Inverse variance weighting (IVW) was used as the primary analysis method. Weighted median (WME) and MR-Egger were used as complementary analysis methods to assess causal effects. To explore the causal relationship between hypothyroidism and frozen shoulder. Sensitivity test analysis was performed using heterogeneity test, multiple validity test, and leave-one-out analysis to explore the robustness of the results. IVW results showed an OR (95% CI) of 1.07 (1.01-1.14), P = .024, indicating that hypothyroidism is a risk factor for a frozen shoulder. And no pleiotropy was found by the test, and sensitivity analysis also showed robust results. This study used 2-sample MR analysis to analyze and explore the genetic data, and the results showed a higher prevalence of frozen shoulder in patients with hypothyroidism, suggesting that active control of hypothyroidism may reduce the occurrence of frozen shoulder.