Using genetic instruments to estimate the causal effect of hormonal reproductive factors on osteoarthritis

The U-curve associations of birth interval with prevalence of osteoarthritis in postmenopausal women

BACKGROUND

To explore associations of birth interval, age at first birth (AFB), age at last birth (ALB) with prevalence of osteoarthritis (OA) in United States (U.S.) postmenopausal women with two deliveries.

METHODS

Cross-sectional analysis of 3088 postmenopausal women with two deliveries from the National Health and Nutrition Examination Survey (1999-2018). Weighted multivariable logistic regression, subgroup analysis and restricted cubic spline (RCS) models were used to examine association of reproductive factors (birth interval, AFB and ALB) with OA risk.

RESULTS

The prevalence of OA was 30.6%. According to RCS, we found the U-shaped relationships were observed between AFB, ALB, birth interval and risk or OA in postmenopausal women. 24-25 years for AFB, 25-30 years for ALB, and 4-6 years for birth interval were associated with lowest OA risk. These associations persisted across various subgroups.

CONCLUSIONS

AFB, ALB and birth interval shown the U-shaped associations with OA prevalence in postmenopausal women with two deliveries. These findings highlight the potential long-term impacts of reproductive history on musculoskeletal health and may inform strategies for OA prevention in U.S. postmenopausal women.

Causal factors for osteoarthritis risk revealed by mendelian randomization analysis

Osteoarthritis (OA), a prevalent chronic disease among the elderly, presents a complex pathogenesis and currently lacks effective treatment. Traditional observational studies are time-consuming, labor-intensive, susceptible to confounding factors, and cannot establish causal relationships. Mendelian randomization (MR) analysis, leveraging genetic variation to assess causal associations between exposures and outcomes, offers a cost-effective and efficient alternative. Over the past decade, large-scale genome-wide association studies have identified numerous genetic variants linked to OA risk factors, facilitating MR study design. In this review, we systematically identified 52 MR studies meeting specific criteria and evaluated their quality, exploring the impact of lifestyle, nutrition, comorbidities, circulating metabolites, plasma proteins, and other health factors on OA risk. We discuss the results and potential mechanisms of MR findings, addressing conflicting evidence based on existing literature and our prior research. With the ongoing expansion of genome-wide association data, we anticipate MR's role in future OA studies to broaden, particularly in drug development research using targeted MR approaches. We thus aim for this paper to offer valuable insights for researchers and clinicians in related fields.

Causal relationship from heart failure to kidney function and CKD: A bidirectional two-sample mendelian randomization study

BACKGROUND

Heart Failure (HF) is a widespread condition that affects millions of people, and it is caused by issues with the heart and blood vessels. Even though we know hypertension, coronary artery disease, obesity, diabetes, and genetics can increase the risk of HF and Chronic Kidney Disease (CKD), the exact cause of these conditions remains a mystery. To bridge this gap, we adopted Mendelian Randomization (MR), which relies on genetic variants as proxies.

METHODS

We used data from European populations for our Bidirectional Two-Sample MR Study, which included 930,014 controls and 47,309 cases of HF from the HERMES consortium, as well as 736,396 controls and 51,256 cases of CKD. We also employed several MR variations, including MR-Egger, Inverse Variance Weighted (IVW), and Weighted Median Estimator (WME), to guarantee the results were accurate and comprehensive.).

RESULTS

In this study, the MR analysis found that individuals with a genetic predisposition for HF have an elevated risk of CKD. Our study revealed a significant association between the genetic prediction of HF and the risk of CKD, as evidenced by the IVW method [with an odds ratio (OR) of 1.12 (95% CI, 1.03-1.21), p = 0.009] and the WME [with an OR of 1.14 (95% CI, 1.03-1.26), p = 0.008]. This causal relationship remained robust even after conducting MR analysis while adjusting for the effects of diabetes and hypertension, yielding ORs of 1.13 (IVW:95% CI, 1.03-1.23), 1.12 (MR-Egger: 95% CI, 0.85-1.48), and 1.15 (WME:95% CI, 1.04-1.27) (p = 0.008). However, in the reverse analysis aiming to explore CKD and renal function as exposures and HF as the outcome, we did not observe a statistically significant causal link between CKD and HF.

CONCLUSION

Our study demonstrates the significance of HF in CKD progression, thus having meaningful implications for treatment and the potential for discovering new therapies. To better understand the relationship between HF and CKD, we need to conduct research in a variety of populations.

Causal effect of gallstone disease on the risk of coronary heart disease or acute myocardial infarction: a Mendelian randomization study

Gallstone disease (GSD) is thought to be associated with the risk of coronary heart disease (CHD) or acute myocardial infarction (AMI), which may be due to abnormal cholesterol metabolism. We used multiple Mendelian randomization (MR) methods based on publicly available genome-wide association study data to assess whether this association is genetically causal and to search for loci driving causality. Pooled data for GSD were obtained from FinnGen Biobank and Biobank Japan, while CHD and AMI were obtained as pooled data from the CARDIoGRAMplusC4D consortium. In this MR study, we found a significant negative causal effect of genetic susceptibility to GSD on AMI in the Finnish population, but no causal effect was found on CHD. This causal effect was not confounded by reverse causality and the same findings were obtained in the Japanese population. Furthermore, the negative causal effect of GSD on AMI risk may be driven by the rs4245791-regulated ABCG5/8 protein. In conclusion, the results of this MR study support a negative causal effect of GSD on AMI and suggest that rs4245791 is the causal driver locus of this effect, which provides new ideas and evidence for the prevention and etiologic study of AMI in patients with GSD.

Review of mendelian randomization studies on age at natural menopause

Menopause marks the end of the reproductive phase of life. Based on epidemiological studies, abnormal age at natural menopause (ANM) is thought to contribute to a number of adverse outcomes, such as osteoporosis, cardiovascular disease, and cancer. However, the causality of these associations remains unclear. A powerful epidemiological method known as Mendelian randomization (MR) can be used to clarify the causality between ANM and other diseases or traits. The present review describes MR studies that included ANM as an exposure, outcome and mediator. The findings of MR analyses on ANM have revealed that higher body mass index, poor educational level, early age at menarche, early age at first live birth, early age at first sexual intercourse, and autoimmune thyroid disease appear to be involved in early ANM etiology. The etiology of late ANM appears to be influenced by higher free thyroxine 4 and methylene tetrahydrofolate reductase gene mutations. Furthermore, early ANM has been found to be causally associated with an increased risk of osteoporosis, fracture, type 2 diabetes mellitus, glycosylated hemoglobin, and the homeostasis model of insulin resistance level. In addition, late ANM has been found to be causally associated with an increased systolic blood pressure, higher risk of breast cancer, endometrial cancer, endometrioid ovarian carcinoma, lung cancer, longevity, airflow obstruction, and lower risk of Parkinson's disease. ANM is also a mediator for breast cancer caused by birth weight and childhood body size. However, due to the different instrumental variables used, some results of studies are inconsistent. Future studies with more valid genetic variants are needed for traits with discrepancies between MRs or between MR and other types of epidemiological studies.