Causal associations between thyroid dysfunction and COVID-19 susceptibility and severity: A bidirectional Mendelian randomization study

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.

Comparative analysis of clinical profile, laboratory profile and outcome in COVID-19 patients with and without hypothyroidism

Objectives

Previous studies suggest that patients' thyroid status might directly impact the course of Coronavirus disease 2019 (COVID-19). The objective of the study was to determine the clinical profile of COVID-19 patients with hypothyroidism and compare it with that of COVID-19 patients without hypothyroidism.

Design

Retrospective observational study.

Setting

The study was conducted in a tertiary healthcare centre in Tamil Nadu between May and June 2021.

Participants

The study included 117 patients admitted with hypothyroidism and COVID-19 as well as 117 age and Gender matched COVID-19 patients without hypothyroidism.

Main outcome measures

Data regarding the demography, comorbidities, presenting symptoms, method of diagnosis of COVID-19, computed tomography (CT) severity score, Interleukin 6 (IL-6), D-dimer, oxygen requirement, number of days in hospital and outcome were collected for both groups. Data analysis was conducted, and p<0.05 was considered statistically significant.

Results

The study comprised 234 patients over two months, from May to June 2021. Distribution of presenting symptoms showed that the hypothyroidism group presented with a higher incidence of fever (66.67%), loose stool (18.80%) and myalgia (7.69%). Results show that RTPCR+, O2 Requirement, death, D-dimer, IL-6, number of days admitted as well as CT-severity did not show any statistically significant differences (p>0.05) between both groups. The outcomes also showed that both groups reported four mortalities.

Conclusions

The results of the study help conclude that the hypothyroidism status of a COVID-19 patient is not associated with higher severity of clinical symptoms, deranged laboratory values as well as mortality.

Funding

None declared.

Causal associations between severe COVID-19 and diseases of seven organs: a proteome-wide mendelian randomization study

The coronavirus disease 2019 (COVID-19) pandemic poses an enormous threat to public health worldwide. Many retrospective studies and case reports to date have shown associations between severe COVID-19 and diseases of multi-organs. However, the research on the causal mechanisms behind this phenomenon is neither extensive nor comprehensive. We conducted a proteome-wide Mendelian randomization (MR) study using summary statistics from a Genome-Wide Association Studies (GWAS) of severe COVID-19 and diseases related to seven organs: lung, spleen, liver, heart, kidney, testis, and thyroid, based on the European ancestry. The primary analytical method used is the radial inverse variance-weighted (radial IVW) method, supplemented with the inverse variance-weighted (IVW), weighted-median (WM), MR-Egger methods. Our findings have confirmed the association between severe COVID-19 and multiple organ-related diseases, such as Hypothyroidism, strict autoimmune (HTCBSA), Thyroid disorders (TD), and Graves' disease (GD). And we have also identified certain proteins that are associated with organ-related diseases, such as Superoxide Dismutase 2 (SOD2) and TEK Receptor Tyrosine Kinase (TEK), which are also considered potential drug targets. Phenotype scanning and sensitivity analyses were implemented to consolidate the results for Mendelian randomization. This study provides a compelling foundation for investigating COVID-19 caused diseases in future studies.

Determining the frequency of thyroid involvement in chest CT scans of COVID-19 patients and its correlation with the severity of lung involvement and survival of patients in 2020

Introduction

This study aimed to determine the frequency of thyroid gland involvement in chest CT scans of patients with COVID-19 admitted to university-affiliated hospitals and assess its relationship with the severity of lung involvement and patient survival in 2020.

Material and methods

In this retrospective cross-sectional study, 1000 PCR-positive patients with COVID-19 who were referred to University-affiliated Hospital in 2020 and had chest CT performed within 72 hours of admission to the hospital were examined. The data was collected by patient file information and CT findings recorded in the PACS system, including thyroid involvement, the severity of lung involvement, and findings related to the death and recovery of patients.

Results

The mean age of the examined patients was 56 years. 525 people (52.5%) were men, and 475 (47.5%) were women. 14% had severe pulmonary involvement, and 9.3% had very severe involvement. Moreover, 15.9 percent of them had deceased. 19.7% had focal thyroid involvement, 14% had diffuse involvement, and 66.3% were healthy subjects. Male gender and older age showed a significant relationship with thyroid gland involvement. The severity of lung involvement, the death rate in patients, and hospitalization in ICU were also significantly related to thyroid gland involvement in patients with COVID.

Discussion and conclusion

This study highlights the importance of considering thyroid-gland involvement in the comprehensive management of COVID-19 patients. Routine screening and monitoring of thyroid-function may facilitate earlier detection and appropriate management of thyroid-related complications, potentially improving clinical outcomes. This study suggests that in COVID-19 infection the monitoring of thyroid function is prudent, particularly in cases of more serious disease.

Thyroid Density in CT Imaging as a Potential Marker of Lung Involvement in COVID-19: A Retrospective Analysis

Background The SARS-CoV-2 pandemic has underscored the multifaceted impact of the virus on human health, extending beyond the respiratory system to involve other organ systems, including the endocrine system. Emerging evidence suggests a notable interaction between COVID-19 and thyroid function, characterized by alterations in thyroid hormone levels and structural changes within the gland. This study aims to explore the association between thyroid density on CT imaging and lung involvement in patients with COVID-19, potentially offering new insights into the systemic effects of the virus. Methodology A retrospective cross-sectional analysis was conducted on 1,066 patients with COVID-19 who underwent chest CT scans without contrast at Government Medical College, Omandurar Government Estate, Chennai, which was designated as the COVID-19 care center from April to June 2021. Thyroid density and lung involvement were quantitatively assessed, and their correlation was analyzed using descriptive and inferential statistics, including the Kruskal-Wallis H test and Shapiro-Wilk test for normality. Results The study population predominantly exhibited normal thyroid density (749, 70.3%), followed by altered (212, 19.9%), nodular (104, 9.8%), and a single instance (0.1%) of absent thyroid density. Despite variability in lung involvement across different thyroid density categories, statistical analysis revealed no significant association between thyroid density and the extent of lung involvement in patients with COVID-19. Conclusions This study found no significant correlation between thyroid density and lung involvement in patients with COVID-19, suggesting that thyroid density on CT imaging may not serve as a reliable marker for lung involvement in this population. Further research is warranted to explore the complex interactions between COVID-19 and thyroid function, as well as the potential implications for patient management and prognosis.

The Aftermath of COVID-19: Exploring the Long-Term Effects on Organ Systems

BACKGROUND

Post-acute sequelae of SARS-CoV-2 infection (PASC) is a complicated disease that affects millions of people all over the world. Previous studies have shown that PASC impacts 10% of SARS-CoV-2 infected patients of which 50-70% are hospitalised. It has also been shown that 10-12% of those vaccinated against COVID-19 were affected by PASC and its complications. The severity and the later development of PASC symptoms are positively associated with the early intensity of the infection.

RESULTS

The generated health complications caused by PASC involve a vast variety of organ systems. Patients affected by PASC have been diagnosed with neuropsychiatric and neurological symptoms. The cardiovascular system also has been involved and several diseases such as myocarditis, pericarditis, and coronary artery diseases were reported. Chronic hematological problems such as thrombotic endothelialitis and hypercoagulability were described as conditions that could increase the risk of clotting disorders and coagulopathy in PASC patients. Chest pain, breathlessness, and cough in PASC patients were associated with the respiratory system in long-COVID causing respiratory distress syndrome. The observed immune complications were notable, involving several diseases. The renal system also was impacted, which resulted in raising the risk of diseases such as thrombotic issues, fibrosis, and sepsis. Endocrine gland malfunction can lead to diabetes, thyroiditis, and male infertility. Symptoms such as diarrhea, nausea, loss of appetite, and taste were also among reported observations due to several gastrointestinal disorders. Skin abnormalities might be an indication of infection and long-term implications such as persistent cutaneous complaints linked to PASC.

CONCLUSIONS

Long-COVID is a multidimensional syndrome with considerable public health implications, affecting several physiological systems and demanding thorough medical therapy, and more study to address its underlying causes and long-term effects is needed.

The association between COVID-19 and infertility: Mendelian randomization analysis

Since December 2019, COVID-19 has triggered a global pandemic. The association of COVID-19 with the long-term reproductive situation of women and males is not clear. Thus, our aim was to assess the causal association between COVID-19 and infertility using Mendelian randomization (MR) analysis based on the OpenGWAS database. Two-sample MR analysis was conducted using one genome-wide association study (GWAS) on COVID-19 and infertility in individuals of European ancestry. The summary data of genetic variation come from the GWAS in European populations. We applied several MR methods, including MR Egger, weighted median, inverse variance weighted, simple mode, weighted mode, to test causal relationships. After observing the statistical analysis results of MR, we conducted sensitivity analysis to test robustness. After gene prediction, it was found that there was no clear causal relationship between COVID-19 and male infertility in MR analysis [OR 0.4702 (95% CI, 0.1569-1.4093), P = .178]. Moreover, COVID-19 was not associated with female infertility [OR 0.9981 (95% CI, 0.763-1.544), P = .646]. Sensitivity analysis showed that the MR results were robust [level pleiotropy, male: (MR-Egger, intercept = 0.1967434; se = 0.1186876; P = .2392406); female: (MR-Egger, intercept = -0.05902506; se = 0.05362049; P = .3211367)]. To further validate the impact of COVID-19 on infertility, we added a covariate (sex hormone binding global levels, abortion) to the MR analysis, which is a multivariate MR analysis. According to univariate and multivariate MR analyses, the evidence does not support that COVID-19 is a causal risk factor for infertility in European population. This information can provide information for doctors in reproductive centers when managing infertility patients.

Mendelian randomization supports genetic liability to hospitalization for COVID-19 as a risk factor of pre-eclampsia

Background

Pre-eclampsia and eclampsia are among the major threats to pregnant women and fetuses, but they can be mitigated by prevention and early screening. Existing observational research presents conflicting evidence regarding the causal effects of coronavirus disease 2019 (COVID-19) on pre-eclampsia risk. Through Mendelian randomization (MR), this study aims to investigate the causal effect of three COVID-19 severity phenotypes on the risk of pre-eclampsia and eclampsia to provide more rigorous evidence.

Methods

Two-sample MR was utilized to examine causal effects. Summary-level data from genome-wide association studies (GWAS) of individuals of European ancestry were acquired from the GWAS catalog and FinnGen databases. Single-nucleotide polymorphisms associated with COVID-19 traits at p < 5 × -8 were obtained and pruned for linkage disequilibrium to generate instrumental variables for COVID-19. Inverse variance weighted estimates were used as the primary MR results, with weighted median and MR-Egger as auxiliary analyses. The robustness of the MR findings was also evaluated through sensitivity analyses. Bonferroni correction was applied to primary results, with a p < 0.0083 considered significant evidence and a p within 0.083-0.05 considered suggestive evidence.

Results

Critical ill COVID-19 [defined as hospitalization for COVID-19 with either a death outcome or respiratory support, OR (95% CI): 1.17 (1.03-1.33), p = 0.020] and hospitalized COVID-19 [defined as hospitalization for COVID-19, OR (95% CI): 1.10 (1.01-1.19), p = 0.026] demonstrated suggestive causal effects on pre-eclampsia, while general severe acute respiratory syndrome coronavirus 2 infection did not exhibit a significant causal effect on pre-eclampsia. None of the three COVID-19 severity phenotypes exhibited a significant causal effect on eclampsia.

Conclusions

Our investigation demonstrates a suggestive causal effect of genetic susceptibility to critical ill COVID-19 and hospitalized COVID-19 on pre-eclampsia. The COVID-19 severity exhibited a suggestive positive dose-response relationship with the risk of pre-eclampsia. Augmented attention should be paid to pregnant women hospitalized for COVID-19, especially those needing respiratory support.

Causal effect of systemic lupus erythematosus on psychiatric disorders: A two-sample Mendelian randomization study

BACKGROUND

This study aims to investigate the association between systemic lupus erythematosus (SLE) and the risk of seven psychiatric disorders through the application of Mendelian randomization (MR) analysis due to previous observational studies that have suggested a potential link between SLE and psychiatric disorders.

METHODS

We collected genetic instruments for SLE from a genome-wide association study (GWAS) involving 23,210 individuals. Seven psychiatric traits were enrolled from the recent largest GWAS, including major depression disorder (MDD), generalized anxiety disorder (GAD), schizophrenia (SCZ), bipolar disorder (BID), autism spectrum disorder (ASD), attention deficit/hyperactivity disorder (ADHD), and insomnia. Summary statistics for psychiatric disorders were obtained from different GWAS meta-analysis studies. The inverse variance weighted (IVW) method was used as the main MR analysis.

RESULTS

The IVW method indicated that SLE is associated with a higher risk of GAD (OR = 1.072, 95 % CI [1.017-1.129], P = 0.008) and SCZ (OR = 3.242, 95 % CI [1.578-6.660], P = 0.007). However, no evidence was found for the causal associations between SLE and other psychiatric disorders. Further analyses found no evidence of pleiotropy and heterogeneity.

CONCLUSIONS

This two-sample MR analysis provides evidence that genetically predicted SLE may increase the risk of GAD and SCZ in a European population. Future studies are needed to elucidate and investigate the mechanisms underlying these causal relationships. Considering the existence of racial genomic heterogeneity, our findings must be viewed with caution.

The Influence of Autoimmune Thyroid Diseases on Viral Pneumonia Development, Including COVID-19: A Two-Sample Mendelian Randomization Study

The association between thyroid function and viral pneumonia has undergone extensive examination, yet the presence of a causal link remains uncertain. The objective of this paper was to employ Two-Sample Mendelian Randomization (MR) analysis to investigate the connections between three thyroid diseases and thyroid hormone indicators with viral pneumonia and COVID-19. We obtained summary statistics datasets from seven genome-wide association studies (GWASs). The primary method used for estimating relationships was inverse-variance weighting (IVW). In addition, we employed weighted median, weighted mode, MR-Egger, and MR-PRESSO as supplementary analytical tools. Sensitivity analyses encompassed Cochran's Q test, MR-Egger intercept test, and MR-PRESSO. Our study revealed significant causal relationships between having a genetic predisposition to autoimmune thyroid disease (AITD) and an increased susceptibility to viral pneumonia (odds ratio [OR]: 1.096; 95% confidence interval [CI]: 1.022-1.176). Moreover, it demonstrated a heightened susceptibility and severity of COVID-19 (OR for COVID-19 susceptibility, COVID-19 hospitalization, and COVID-19 critical illness, with 95% CIs of 1.016, 1.001-1.032; 1.058, 1.003-1.116; 1.045, 1.010-1.081). However, no statistically significant associations were found between TSH, FT4, subclinical hypo- or hyperthyroidism, and the risk of viral pneumonia incidence, or the susceptibility and severity of COVID-19 (all p > 0.05). This study establishes a cause-and-effect relationship between AITD and the development of viral pneumonia, as well as the susceptibility and severity of COVID-19.

Exploring the Potential Association between COVID-19 and Thyroid Cancer: A Mendelian Randomization Study

In order to address the ongoing debate surrounding the potential link between COVID-19 and thyroid cancer, our study was specifically designed to investigate the association between these two factors. We acquired summary data from a genome-wide association study (GWAS) concerning COVID-19 susceptibility and severity of COVID-19 in the European population, with a focus on their relationship with thyroid cancer. We applied three distinct methodologies to evaluate the causality between COVID-19 and thyroid cancer, employing Mendelian randomization (MR)-Egger, weighted median (WM), and inverse variance-weighted (IVW) approaches. Furthermore, we utilized a variety of techniques to assess pleiotropy and heterogeneity, including the MR-Egger intercept, MR-pleiotropy residual sum and outlier method (PRESSO), and Cochran's Q test. The MR analysis revealed associations between the susceptibility of COVID-19 and thyroid cancer (IVW odds ratio [OR]: 2.826, 95% confidence interval [CI]: [0.842, 9.483], P = 0.093) as well as between the risk of COVID-19 hospitalization and thyroid cancer (IVW OR: 1.630, 95% CI: [1.050, 2.529], P = 0.029). However, the relationship between COVID-19 and the occurrence of severe thyroid cancer cases was less evident (IVW OR: 1.061, 95% CI: [0.575, 1.956], P = 0.850). Our sensitivity analyses did not reveal any signs of horizontal pleiotropy or heterogeneity. Our MR study provided compelling evidence supporting a causal connection between the risk of COVID-19 hospitalization and thyroid cancer. Nevertheless, the MR results derived from genetic data do not support a causal link between susceptibility to COVID-19 and the risk of thyroid cancer or between very severe cases of COVID-19 and the risk of thyroid cancer. These findings have significant implications for further investigations into the impact of COVID-19 on health and the etiology of thyroid cancer.

Association between COVID-19 and myasthenia gravis (MG): A genetic correlation and Mendelian randomization study

BACKGROUND

Observational studies have suggested an association between coronavirus disease 2019 (COVID-19) and myasthenia gravis (MG). Here, we aimed to estimate the genetic correlation and causal relationship between COVID-19 susceptibility, hospitalization, severity, and MG phenotypes using linkage disequilibrium score regression (LDSC) and Mendelian randomization (MR) approach.

METHODS

Summary statistics of COVID-19 susceptibility, hospitalization, and severity were used as instrumental variables for exposure traits. Large-scale genome-wide association study (GWAS) data for MG were used as outcome traits. The inverse variance weighted approach was used for the main MR analysis, complemented by MR-Egger, weighted median, simple mode, and weighted mode methods. Sensitivity analysis was implemented using Cochran's Q test, MR-PRESSO method, and MR-Egger intercept test.

RESULTS

LDSC analysis did not reveal any genetic correlation among COVID-19 susceptibility, hospitalization, severity, and MG phenotypes, including MG, early-onset MG, and late-onset MG (p > .05). Our MR analysis did not provide evidence supporting a causal effect of COVID-19 susceptibility, hospitalization, or severity on MG phenotypes (p > .05). Extensive sensitivity analysis strengthened the robustness and consistency of the MR estimates.

CONCLUSION

Our study did not find evidence of a genetic correlation or causal relationship among COVID-19 susceptibility, hospitalization, severity, and MG. Future studies with more GWAS data are needed to evaluate the association between COVID-19 phenotypes and MG and its subgroups.

The causal relationship between gut microbiota and bone mineral density: a Mendelian randomization study

Background

The gut microbiota has emerged as an intriguing and potentially influential factor in regulating bone health. However, the causal effect of the gut microbiota on bone mineral density (BMD) appears to differ throughout various life stages.

Methods

We conducted a Mendelian randomization (MR) analysis to investigate the potential causal relationship between gut microbiota and BMD in five distinct age groups: 0-15, 15-30, 30-45, 45-60, and 60 years and older. The analysis employed three different methods, namely MR-Egger, weighted median, and Inverse-variance weighting, to ensure the robustness of our findings, a series of sensitivity analyses were also conducted, such as horizontal pleiotropy tests, heterogeneity tests, and leave-one-out sensitivity tests.

Results

In the age group of 0-15 years, Eubacterium_fissicatena_group and Eubacterium_hallii_group were identified as risk factors for BMD. During the 15-30 age group, Phascolarctobacterium, Roseburia, and Ruminococcaceae_UCG_003 were found to be protective factors for BMD. In the 30-45 age group, Lachnospira genus demonstrated a protective effect on BMD, while Barnesiella and Lactococcus were identified as risk factors for BMD. Moving on to the 45-60 age group, Eubacterium_ventriosum_group, Lachnospiraceae_UCG_004, and Subdoligranulum were observed to be protective factors for BMD, while Eubacterium_coprostanoligenes_group, Fusicatenibacter, and Lactococcus were associated with an increased risk of BMD. In individuals aged 60 years and older, Fusicatenibacter and Ruminococcaceae_UCG_002 were also noted as risk factors for BMD. Conversely, Eubacterium_ruminantium_group, Ruminococcus_gauvreauii_group, Alistipes, and Coprococcus_3 were found to be protective factors for BMD, whereas Barnesiella and Sellimonas were identified as risk factors for BMD.

Conclusion

A robust causal relationship between gut microbiota and bone mineral density (BMD) exists throughout all stages of life, with Firmicutes phylum being the primary group associated with BMD across age groups. Gut microbiota linked with BMD primarily belong to the Firmicutes phylum across age groups. The diversity of gut microbiota phyla associated with BMD depicts relatively stable patterns during the ages of 0-45 years. However, for individuals aged 45 years and above, there is an observed increase in the number of gut microbiota species linked with BMD, and by the age of 60 years, a trend toward an increase in the Bacteroidetes phylum categories is proposed.

Effect of genetic liability to migraine and its subtypes on breast cancer: a mendelian randomization study

BACKGROUND

The relationship between migraine and breast cancer risk has generated conflicting findings. We attempted to assess the association between migraine and breast cancer risk using Mendelian randomization (MR) analysis.

METHODS

We selected genetic instruments associated with migraine from a recently published genome-wide association studies (GWAS). Inverse variant weighted (IVW) analysis was adopted as the main method, and we also performed the weighted-median method and the MR‒Egger, MR pleiotropy residual sum and outlier (MR-PRESSO), and MR Robust Adjusted Profile Score (MR-RAPS) methods as supplements.

RESULTS

Our MR suggested that any migraine (AM) was a risk factor for overall breast cancer (IVW: odds ratio (OR) = 1.072, 95% confidence intervals (CI) = 1.035-1.110, P = 8.78 × 10- 5, false discovery rate (FDR) = 7.36 × 10- 4) and estrogen receptor-positive (ER+) breast cancer (IVW: OR = 1.066, 95% CI = 1.023-1.111, P = 0.0024; FDR = 0.0108) but not estrogen receptor-negative (ER-) breast cancer. In its subtype analysis, women with a history of migraine without aura (MO) had an increased risk of ER- breast cancer (IVW: OR = 1.089, 95% CI = 1.019-1.163, P = 0.0118, FDR = 0.0354), and MO was suggestively associated with the risk of overall breast cancer (FDR > 0.05 and IVW P < 0.05). No significant heterogeneity or horizontal pleiotropy was found in the sensitivity analysis.

CONCLUSION

This study suggested that women with AM have an increased risk of overall breast cancer and ER + breast cancer. MO was suggestively associated with the risk of overall breast cancer and ER- breast cancer.

Assessing causal relationship between circulating cytokines and age-related neurodegenerative diseases: a bidirectional two-sample Mendelian randomization analysis

Numerous studies have reported that circulating cytokines (CCs) are linked to age-related neurodegenerative diseases (ANDDs); however, there is a lack of systematic investigation for the causal association. A two-sample bidirectional Mendelian Randomisation (MR) method was utilized to evaluate the causal effect. We applied genetic variants correlated with concentrations of CCs from a genome-wide association study meta-analysis (n = 8293) as instrumental variables. Summary data of three major ANDDs [Alzheimer's disease (AD), Parkinson's disease (PD), and Amyotrophic lateral sclerosis (ALS)] were identified from the IEU OpenGWAS platform (n = 627, 266). Inverse-variance weighted method is the main approach to analyse causal effect, and MR results are verified by several sensitivity and pleiotropy analyses. In directional MR, it suggested that several CCs were nominally correlated with the risk of ANDDs, with a causal odds ratio (OR) of Interleukin (IL)-5 of 0.909 for AD; OR of IL-2 of 1.169 for PD; and OR of Beta nerve growth factor of 1.142 for ALS). In reverse MR, there were some suggestively causal effects of ANDDs on CCs (AD on increased Basic fibroblast growth factor and IL-12 and decreased Stem cell growth factor beta; PD on decreased Monokine induced by interferon-gamma; ALS on decreased Basic fibroblast growth factor and IL-17). The findings were stable across sensitivity and pleiotropy analyses. However, after Bonferroni correction, there is no statistically significant association between CCs and ANDDs. Through the genetic epidemiological approach, our study assessed the role and presented possible causal associations between CCs and ANDDs. Further studies are warranted to verify the causal associations.