Assessment of the association between genetic factors regulating thyroid function and microvascular complications in diabetes: A two-sample Mendelian randomization study in the European population

Causal associations between childhood obesity and delayed puberty or height: a bidirectional two-sample Mendelian randomization study

OBJECTIVES

Childhood obesity is thought to influence pubertal development, according to observational studies. However, the exact causal relationship remains unclear due to the complexity of factors affecting pubertal development.

METHODS

To explore the association between exposure (childhood obesity) and outcome (delayed puberty, height), we utilized various methods, including inverse-variance weighted (IVW), weighted median, weighted mode, and MR Egger regression. Additionally, sensitivity analyses were conducted using MR-Egger, MR-PRESSO, Cochran's Q, and leave-one-out techniques to ensure the robustness of the results. Additionally, reverse MR analysis was conducted to explore potential reverse causation.

RESULTS

The IVW analysis revealed no significant genetic causal link between childhood obesity and delayed puberty or height (all p>0.05). In the reverse analysis, height had a causal association with childhood obesity (OR=0.85, 95 % CI=0.76-0.96). The Cochran's Q test highlighted heterogeneity in the results concerning childhood obesity and height (p<0.05). But the MR-Egger intercept and MR-PRESSO test confirmed no impact the results pleiotropic bias, supported by leave-one-out sensitivity analysis.

CONCLUSIONS

Our study found no significant genetic causal association between childhood obesity and delayed puberty or height. However, height was causally associated with childhood obesity. Future research should utilize advanced analytical methods to better understand the determinants of pubertal development.

Causal Relationship Between Emotional Disorders and Thyroid Disorders: A Bidirectional Two-Sample Mendelian Randomization Study

INTRODUCTION

The interplay between emotional disorders and thyroid disorders has been subject to numerous observational studies, which have consistently reported associations but have failed to establish clear causal links due to the multifactorial etiology and influences. We conducted a bidirectional two-sample Mendelian randomization (MR) analysis to explore the genetic causal association between emotional disorders and thyroid disorders.

METHODS

We employed several methods, including inverse-variance weighted (IVW), weighted median, weighted mode, and MR Egger regression. Additionally, sensitivity analyses were conducted using MR-Egger, MR Pleiotropy Residual Sum and Outlier (MR-PRESSO), Cochran's Q, and leave-one-out methods.

RESULTS

IVW results showed negative causal relationships between bidirectional emotional disorders and hypothyroidism, toxic single thyroid nodules in thyrotoxicosis, and hyperthyroidism/toxicity. Additionally, there was a positive causal relationship between anxiety disorders and hypothyroidism. IVW results of reverse MR analysis estimates revealed a positive causal relationship between hypothyroidism, autoimmune thyroiditis, and recurrent or chronic depression. Additionally, there was a negative causal relationship between hyperthyroidism/toxicity and bipolar disorder.

CONCLUSION

This bidirectional two-sample MR study preliminarily reveals a complex, bidirectional causal relationship between emotional disorders and thyroid disorders, particularly highlighting the role of thyroid dysfunction in the development of certain emotional disorders and vice versa.

Causal Relationship Between Emotional Disorders and Thyroid Disorders: A Bidirectional Two‐Sample Mendelian Randomization Study

Introduction

The interplay between emotional disorders and thyroid disorders has been subject to numerous observational studies, which have consistently reported associations but have failed to establish clear causal links due to the multifactorial etiology and influences. We conducted a bidirectional two‐sample Mendelian randomization (MR) analysis to explore the genetic causal association between emotional disorders and thyroid disorders.

Methods

We employed several methods, including inverse‐variance weighted (IVW), weighted median, weighted mode, and MR Egger regression. Additionally, sensitivity analyses were conducted using MR‐Egger, MR Pleiotropy Residual Sum and Outlier (MR‐PRESSO), Cochran's Q, and leave‐one‐out methods.

Results

IVW results showed negative causal relationships between bidirectional emotional disorders and hypothyroidism, toxic single thyroid nodules in thyrotoxicosis, and hyperthyroidism/toxicity. Additionally, there was a positive causal relationship between anxiety disorders and hypothyroidism. IVW results of reverse MR analysis estimates revealed a positive causal relationship between hypothyroidism, autoimmune thyroiditis, and recurrent or chronic depression. Additionally, there was a negative causal relationship between hyperthyroidism/toxicity and bipolar disorder.

Conclusion

This bidirectional two‐sample MR study preliminarily reveals a complex, bidirectional causal relationship between emotional disorders and thyroid disorders, particularly highlighting the role of thyroid dysfunction in the development of certain emotional disorders and vice versa.

Association between sensitivity to thyroid hormone indices and type 2 diabetic microvascular complications in euthyroid patients

The correlation between thyroid hormone (TH) sensitivity and microvascular complications of type 2 diabetes mellitus (T2DM) remains uncertain. This study aimed to explore the association between TH sensitivity and the risk of diabetic kidney disease (DKD), diabetic retinopathy (DR), and diabetic neuropathy (DNP) in euthyroid T2DM patients. This study included a total of 946 hospitalized T2DM patients and calculated their sensitivity to the TH index, and each patient completed screenings for DKD, DR, and DNP. Multivariate logistic regression, generalized additive modeling, and subgroup analysis were used to assess the association between TH index sensitivity and the risks of DKD, DR, and DNP. After adjusting for confounding factors, a significant linear correlation was observed between the sensitivity of the thyroid feedback quartile index 3 (TFQI3) and DKD risk. However, the sensitivities of thyroid-stimulating hormone index (TSHI), thyrotropin thyroxine resistance index (TT4RI) and partial thyroid feedback quartile index (PTFQI) exhibited nonlinear correlations with the risk of developing DKD. The effect sizes to the left of the inflection point for TSHI, TT4RI and PTFQI were (odd ratio [OR] = 0.53, 95% confidence interval [CI]: 0.288-0.977), (OR = 0.863, 95%Cl: 0.751-0.992) and (OR = 0.007, 95%Cl: 0-0.724), respectively. However, there was no significant correlation between TH index sensitivity and DR/DNP risk. This study provides valuable insights into the relationship between TH sensitivity and the risks of DKD, DR, and DNP, with substantial clinical implications for individual prediction among T2DM patients.

Application of Mendelian randomization in thyroid diseases: a review

Thyroid diseases are increasingly prevalent, posing significant challenges to patients' quality of life and placing substantial financial burdens on families and society. Despite these impacts, the underlying pathophysiology of many thyroid conditions remains poorly understood, complicating efforts in treatment, management, and prevention. Observational studies can identify associations between exposure variables and disease; however, they often struggle to account for confounding factors and reverse causation. Understanding disease occurrence, epidemiological trends, and clinical diagnosis, prevention, and treatment relies heavily on robust etiological research. Mendelian randomization, a method grounded in genetics and epidemiology, has been widely employed in studying the etiology of thyroid diseases, offering a solution to some of these challenges. This paper categorizes thyroid diseases into thyroid dysfunction and thyroid cancer, reviewing related Mendelian randomization studies. It further provides novel perspectives and approaches for investigating the mechanisms underlying thyroid diseases and designing intervention strategies.

Mendelian randomization analysis reveals causal factors behind diabetic nephropathy: evidence, opportunities, and challenges

Diabetic nephropathy (DN), as the most serious minor vascular complication of diabetes, imposes a significant socioeconomic and medical cost around the world, and its prevention and treatment are a major challenge in the current medical community. Observational studies and randomized controlled trials have revealed protective and risk factors for some DN. However, the conclusions of these researches may be influenced by several types of confounding. Mendelian randomization is a new epidemiological method mainly used to infer the causal relationship between exposure and outcome. Many Mendelian randomization studies have found potential causal relationships between DN and some diseases and lifestyle habits, thus providing valuable data for future mechanistic studies as well as the development and implementation of clinical prevention strategies. As a result, the purpose of this review is to evaluate the published Mendelian randomization study of DN, using the bibliometric research method, analyze the current research status and hot spots, and further summarize the genetic evidence about the potential protection of DN and risk factors to provide new inspiration for the etiology of DN and as a reference for clinical intervention.

Thyroid Function, Diabetes, and Common Age-Related Eye Diseases: A Mendelian Randomization Study

Background: Previous Mendelian randomization (MR) studies showed an association between hypothyroidism and cataract and between high-normal free thyroxine (FT4) and late age-related macular degeneration (AMD), but not between FT4, thyroid stimulating hormone (TSH), or hyperthyroidism and diabetic retinopathy or cataract. These studies included a limited number of genetic variants for thyroid function and did not investigate autoimmune thyroid disease (AITD) or glaucoma, include bidirectional and multivariable MR (MVMR), and examine sex differences or potential mediation effects of diabetes. We aimed to address this knowledge gap. Methods: We examined the causality and directionality of the associations of AITD, and FT4 and TSH within the reference range with common age-related eye diseases (diabetic retinopathy, cataract, early and late AMD, and primary open-angle glaucoma). We conducted a bidirectional two-sample MR study utilizing publicly available genome-wide association study (GWAS) summary statistics from international consortia (ThyroidOmics, International AMD Genetics Consortium, deCODE, UK Biobank, FinnGen, and DIAGRAM). Bidirectional MR tested directionality, whereas MVMR estimated independent causal effects. Furthermore, we investigated type 1 diabetes (T1D) and type 2 diabetes (T2D) as potential mediators. Results: Genetic predisposition to AITD was associated with increased risk of diabetic retinopathy (p = 3 × 10-4), cataract (p = 3 × 10-3), and T1D (p = 1 × 10-3), but less likely T2D (p = 0.01). MVMR showed attenuated estimates for diabetic retinopathy and cataract when adjusting for T1D, but not T2D. We found pairwise bidirectional associations between AITD, T1D, and diabetic retinopathy. Genetic predisposition to both T1D and T2D increased the risk of diabetic retinopathy and cataract (p < 4 × 10-4). Moreover, genetically predicted higher FT4 within the reference range was associated with an increased risk of late AMD (p = 0.01), particularly in women (p = 7 × 10-3). However, we neither found any association between FT4 and early AMD nor between TSH and early and late AMD. No other associations were observed. Conclusions: Genetic predisposition to AITD is associated with risk of diabetic retinopathy and cataract, mostly mediated through increased T1D risk. Reciprocal associations between AITD, diabetic retinopathy, and T1D imply a shared autoimmune origin. The role of FT4 in AMD and potential sex discrepancies needs further investigation.

Genetically mimicked effects of thyroid dysfunction on diabetic retinopathy risk: a 2-sample univariable and multivariable Mendelian randomization study

Background

Thyroid dysfunction exhibits a heightened prevalence among people with diabetes compared to those without diabetes. Furthermore, TD emerges as a notable correlated risk factor for the onset of diabetic retinopathy.

Methods

Using data from the FinnGen database (R9), we investigated the causal relationship between thyroid dysfunction (TD) and four stages of diabetic retinopathy (DR). A two-sample univariable Mendelian randomization (UVMR) approach was employed to estimate the total causal effect of TD on four stages of DR, while multivariable Mendelian randomization (MVMR) was used to assess the direct causal effect. The meta-analysis was conducted to summarize the collective effect of TD on four stages of DR. The inverse variance weighted (IVW) method was the primary approach for Mendelian randomization analysis, with heterogeneity, horizontal pleiotropy, and leave-one-out sensitivity analyses performed to validate the robustness of the findings.

Results

In UVMR analysis, thyrotoxicosis (TOS) was significantly associated with an increased risk of diabetic retinopathy across four stages (OR, 1.10-1.19; P<0.025). However, MVMR analysis, after adjusting for Graves' disease (GD) and/or rheumatoid arthritis (RA), revealed no significant association between TOS and the four stages of diabetic retinopathy. The Meta-analysis demonstrated the collective effect of TOS on diabetic retinopathy across all stages [OR=1.11; 95% CI (1.08-1.15); P<0.01]. In UVMR analysis, the estimates for hypothyroidism (HPT) and GD were similar to those for TOS. In the MVMR analysis, after adjusting for RA, the significant effect of HPT on DR and non-proliferative diabetic retinopathy (NPDR) remained. Additionally, MVMR analysis suggested that the estimates for GD on DR were not affected by TOS, except for GD-proliferative diabetic retinopathy (PDR). However, no significant correlation persisted after adjusting for RA, including for GD-PDR.

Conclusion

Our study demonstrated a significant association between thyroid dysfunction TD and DR, with the relationship being particularly pronounced in HPT-DR.

Thyroid Hormone Signaling in Retinal Development and Function: Implications for Diabetic Retinopathy and Age-Related Macular Degeneration

Thyroid Hormones (THs) play a central role in the development, cell growth, differentiation, and metabolic homeostasis of neurosensory systems, including the retina. The coordinated activity of various components of TH signaling, such as TH receptors (THRs) and the TH processing enzymes deiodinases 2 and 3 (DIO2, DIO3), is required for proper retinal maturation and function of the adult photoreceptors, Müller glial cells, and pigmented epithelial cells. Alterations of TH homeostasis, as observed both in frank or subclinical thyroid disorders, have been associated with sight-threatening diseases leading to irreversible vision loss i.e., diabetic retinopathy (DR), and age-related macular degeneration (AMD). Although observational studies do not allow causal inference, emerging data from preclinical models suggest a possible correlation between TH signaling imbalance and the development of retina disease. In this review, we analyze the most important features of TH signaling relevant to retinal development and function and its possible implication in DR and AMD etiology. A better understanding of TH pathways in these pathological settings might help identify novel targets and therapeutic strategies for the prevention and management of retinal disease.

Advancements in the Management of Endocrine System Disorders and Arrhythmias: A Comprehensive Narrative Review

In recent years, notable advancements have been made in managing endocrine system disorders and arrhythmias. These advancements have brought about significant changes in healthcare providers' approach towards these complex medical conditions. Endocrine system disorders encompass a diverse range of conditions, including but not limited to diabetes mellitus, thyroid dysfunction, and adrenal disorders. Significant advancements in comprehending the molecular underpinnings of these disorders have laid the foundation for implementing personalized medicine. Advancements in genomic profiling and biomarker identification have facilitated achieving more accurate diagnoses and developing customized treatment plans. Furthermore, the utilization of cutting-edge pharmaceuticals and advanced delivery systems presents a significant advancement in achieving enhanced glycemic control and minimizing adverse effects for individuals afflicted with endocrine disorders. Arrhythmias, characterized by irregular heart rhythms, present a substantial risk to cardiovascular well-being. Innovative strategies for managing arrhythmia encompass catheter-based ablation techniques, wearable cardiac monitoring devices, and predictive algorithms powered by artificial intelligence. These advancements facilitate the early detection, stratification of risks, and implementation of targeted interventions, ultimately leading to improved patient outcomes. Incorporating technology and telemedicine has been instrumental in enhancing the accessibility and continuity of care for individuals diagnosed with endocrine disorders and arrhythmias. The utilization of remote patient monitoring and telehealth consultations enables prompt modifications to treatment regimens and alleviates the need for frequent visits to the clinic. This is particularly significant in light of the current global health crisis. This review highlights the interdisciplinary nature of managing endocrine disorders and arrhythmias, underscoring the significance of collaboration among endocrinologists, cardiologists, electrophysiologists, and other healthcare professionals. Multidisciplinary care teams have enhanced their capabilities to effectively address the intricate relationship between the endocrine and cardiovascular systems. In summary, endocrine system disorders and arrhythmias management have undergone significant advancements due to groundbreaking research, technological advancements, and collaborative healthcare approaches. This narrative review provides a comprehensive overview of the advancements, showcasing their potential to enhance patient care, improve quality of life, and decrease healthcare expenses. Healthcare providers must comprehend and integrate these advancements into their clinical practice to enhance outcomes for individuals with endocrine system disorders and arrhythmias.