Using human genetics to understand the disease impacts of testosterone in men and women

Causal relationship between sex hormones and cutaneous melanoma: a two-sample Mendelian randomized study

This study aimed to elucidate the genetic aspects of the relationship between sex hormones and cutaneous melanoma risk, providing valuable insights into this complex association. In this study, we used estradiol, bioavailable testosterone, sex hormone-binding globulin, and total testosterone as the exposure and melanoma as the outcome for two-sample Mendelian randomization analysis. In this study, a random-effects inverse-variance weighting (IVW) model was used as the main analysis model, and the corresponding weighted median, simple mode, weighted mode, and Mendelian randomization‒Egger methods were used as supplementary methods. We assessed both heterogeneity and horizontal pleiotropy in our study, scrutinizing whether the analysis results were affected by any individual single nucleotide polymorphism. The random-effects IVW method indicated that estradiol [odds ratio (OR), 1.000; 95% confidence interval (CI), 0.998-1.003; P  = 0.658], bioavailable testosterone (OR = 1.001, 95% CI, 0.999-1.003; P  = 0.294), sex hormone-binding globulin (IVW: OR, 1.000; 95% CI, 0.998-1.003; P  = 0.658), and total testosterone (IVW: OR, 1.002; 95% CI, 0.999-1.005; P  = 0.135) were not genetically linked to cutaneous melanoma. No analyses exhibited heterogeneity, horizontal pleiotropy, or deviations. We were unable to find genetic evidence for a causal relationship between sex hormones and the occurrence of cutaneous melanoma in this study. These results are limited by sample size and population, so the causal relationship between sex hormones and cutaneous melanoma needs to be further studied.

Assessing the causal relationship between frailty and sex hormone-binding globulin or insulin-like growth factor-1 levels: A sex-stratified bidirectional Mendelian Randomization study

BACKGROUND

The association between frailty and sex hormone-binding globulin (SHBG) or insulin-like growth factor-1(IGF-1) levels demonstrates sex differences with inconsistent conclusions. This study aims to explore the causal relationship between frailty and SHBG or IGF-1 levels through bidirectional Mendelian randomization (MR).

METHODS

We conducted two-sample bidirectional sex-stratified MR analyses using summary-level data from genome-wide association studies (GWASs) to examine the causal relationship between frailty and IGF-1 or SHBG levels, as measured by frailty index (FI) and frailty phenotype (FP). We use the random-effects inverse-variance weighted (IVW), weighted median, MR-Egger, MR-Egger intercept, and leave-one-out approaches.

RESULT

The relationship between frailty and SHBG or IGF-1 levels is inversely related, with a significant decrease in SHBG levels in females. Specifically, SHBG levels significantly decrease with FI (β = -5.49; 95 % CI: -9.67 to -1.32; FDR = 0.02) and more pronounced with FP (β = -10.14; 95 % CI: -16.16 to -4.13; FDR = 0.01), as determined by the IVW approach. However, reverse analysis shows no significant effect of IGF-1 or SHBG levels on either FI or FP (p > 0.05).

CONCLUSION

Our study indicates a negative correlation between frailty and the levels of SHBG and IGF-1. It is suggested that further research is required to establish cut-off values for SHBG and IGF-1 levels in the frailty population. This is particularly important for females at higher risk, such as those undergoing menopause, to enable comprehensive assessment and early prevention efforts. While the findings imply that reduced IGF-1 and SHBG levels may not directly contribute to frailty, it is important not to overlook the underlying mechanisms through which they may indirectly influence frailty.

Di-(2-ethylhexyl) phthalate exposure induces premature testicular senescence by disrupting mitochondrial respiratory chain through STAT5B-mitoSTAT3 in Leydig cell

Di-(2-ethylhexyl) phthalate (DEHP), a prevalent plasticizer, is known to have endocrine-disrupting effects on males and cause reproductive toxicity. There were causal effects of DEHP on testosterone levels in the real world by Mendelian randomization analysis. Exposure to DEHP during the preadult stage might lead to premature testicular senescence, but the mechanisms responsible for this have yet to be determined. In this study, we administered DEHP (300 mg/kg/day) to male C57BL/6 mice from postnatal days 21 to 49. The mice were kept for 6 months without DEHP. RNA sequencing was conducted on testicular tissue at PNM6. The results indicated that DEHP hindered testicular development, lowered serum testosterone levels in male mice, and induced premature testicular senescence. TM3 Leydig cells were exposed to 300 μM of mono(2-ethylhexyl) phthalate (MEHP), the bioactive metabolite of DEHP, for 72 h. The results also found that DEHP/MEHP induced senescence in vivo and in vitro. The mitochondrial respiratory chain was disrupted in Leydig cells. The expression and stability of STAT5B were elevated by MEHP treatment in TM3 cells. Furthermore, p-ERK1/2 was significantly decreased by STAT5B, and mitochondria-STAT3 (p-STAT3 ser727) was significantly decreased due to the decrease of p-ERK1/2. Additionally, the senescence level of TM3 cells was decreased and treated with 5 mM NAC for 1 h after MEHP treatment. In conclusion, these findings provided a novel mechanistic understanding of Leydig cells by disrupting the mitochondrial respiratory chain through STAT5B-mitoSTAT3.

Association between phthalates exposure and all-cause mortality among diabetic cases: A prospective study

The aim of this study was to explore the association between phthalates (PAEs) exposure and all-cause mortality among diabetic cases, and potential molecular mechanisms of the effect. We followed 2806 diabetes cases from 2008 to the end of 2018 based on the Dongfeng-Tongji study, of which 446 cases died. We measured serum levels of six PAEs (DMP, DEP, DiBP, DnBP, BBP, and DEHP). Cox models were used to investigate the associations between PAEs and all-cause mortality. Genes related to PAEs are obtained from the Comparative Toxicogenomics Database. We constructed polygenic scores for sex hormone-binding globulin (SHBG) and testosterone, and functional SNPs for IL-6, PPARG, and GPX1 from genotyping data, and further analyzed the environment-gene interactions. The positive associations of PAEs (DMP, DiBP, DnBP, DEHP) with mortality were only observed in males but not in females. Comparing with the extreme quartile 1, the HRs (95% CI) for quartile 4 were 1.63 (0.17, 2.26) for DMP, 1.82 (1.29, 2.56) for DiBP, 1.68 (1.18, 2.40) for DnBP, 1.66 (1.17, 2.36) for DEHP. Enrichment analysis showed that PAEs-related genes were mainly associated with hormones and IL-6-related pathways. Genetic variants of SHBG, testosterone, and IL-6 modified the association between PAEs mixture and all-cause mortality. PAEs exposure are associated with all-cause mortality among diabetic cases, and PAE exposure increases the risk of all-cause mortality only in males. Effects on the hormonal system and IL6-related pathways may be potential mechanisms.

Joint models reveal genetic architecture of pubertal stage transitions and their association with BMI in admixed Chilean population

Early or late pubertal onset can lead to disease in adulthood, including cancer, obesity, type 2 diabetes, metabolic disorders, bone fractures, and psychopathologies. Thus, knowing the age at which puberty is attained is crucial as it can serve as a risk factor for future diseases. Pubertal development is divided into five stages of sexual maturation in boys and girls according to the standardized Tanner scale. We performed genome-wide association studies (GWAS) on the "Growth and Obesity Chilean Cohort Study" cohort composed of admixed children with mainly European and Native American ancestry. Using joint models that integrate time-to-event data with longitudinal trajectories of body mass index (BMI), we identified genetic variants associated with phenotypic transitions between pairs of Tanner stages. We identified $42$ novel significant associations, most of them in boys. The GWAS on Tanner $3\rightarrow 4$ transition in boys captured an association peak around the growth-related genes LARS2 and LIMD1 genes, the former of which causes ovarian dysfunction when mutated. The associated variants are expression and splicing Quantitative Trait Loci regulating gene expression and alternative splicing in multiple tissues. Further, higher individual Native American genetic ancestry proportions predicted a significantly earlier puberty onset in boys but not in girls. Finally, the joint models identified a longitudinal BMI parameter significantly associated with several Tanner stages' transitions, confirming the association of BMI with pubertal timing.

Genetic Causal Relationship Between Sex Hormones and Basal Cell Carcinoma: A Two-Sample Mendelian Randomization Study

Background

The primary aim of this study was to explore whether sex hormones affect the occurrence of basal cell carcinoma (BCC) from a genetic perspective using a two-sample Mendelian randomization (MR) study.

Methods

Exposure and outcome data for this MR analysis were derived from previously published GWAS studies. In this study, estradiol, sex hormone-binding globulin (SHBG), bioavailable testosterone, and total testosterone were used as exposures, and BCC was used as the outcome for the two-sample MR analysis. The random effects inverse variance weighted (IVW) model was the primary analytical model, and the simple mode, weighted median, MR-Egger, and weighted mode methods were applied as complementary approaches. Furthermore, the "leave-one-out" sensitivity analysis was performed to assess stability, Cochran's Q test to evaluate heterogeneity, and the MR-Egger intercept test to analyze horizontal multiplicity.

Results

The two-sample MR analysis of the sex hormone and BCC showed that estradiol, sex hormone-binding globulin (SHBG), bioavailable testosterone, and total testosterone were not a causal factor in BCC (P>0.05). The results of the heterogeneity test and horizontal pleiotropic analysis showed that no heterogeneity or horizontal pleiotropic existed in all MR analyses (Cochran's Q-P>0.05, Egger intercept-P>0.05).

Conclusion

The two-sample MR analysis showed that estrogen and testosterone did not affect the occurrence and development of BCC at the genetic level.

The impact of sex hormones on metabolic syndrome: univariable and multivariable Mendelian randomization studies

BACKGROUND

Observational studies have found associations between sex hormones and metabolic syndrome(Mets), but the causal relationships remains unclear. This study utilizes univariable and multivariable Mendelian randomization (MR) to elucidate the associations between sex hormones (including sex hormone-binding globulin(SHBG), estradiol(E2), testosterone(T)) and Mets and its subtypes (including waist circumference(WC), fasting blood glucose(FBG), high blood pressure(HBP), high-density lipoprotein(HDL-C), triglycerides(TG)).

METHODS

We utilized summary data from large-scale genome-wide association studies. Univariable Mendelian randomization (UMVMR) analysis was primarily conducted using the inverse variance weighted method (IVW), with secondary analyses employing the weighted median, MR-Egger regression, simple mode method, and weighted mode method. Subsequently, multivariable Mendelian randomization (MVMR) was employed to assess the causal relationships between SHBG, T, E2, and MetS and its components: WC, FPG, HBP, HDL-C, and TG. Sensitivity analyses were conducted to assess result reliability.

RESULTS

Genetically predicted SHBG was significantly negatively associated with MetS (UMVMR: β=-0.72; 95% CI = 0.41 to 0.57; P = 1.28e-17; MVMR: β=-0.60; 95% CI=-0.83 to -0.38; P < 0.001). Positive causal relationships were observed between SHBG and WC(MVMR: β = 0.10; 95% CI = 0.03 to 0.17; P = 0.01) and HDL-C (MVMR: β = 0.41; 95% CI = 0.21 to 0.60; P < 0.001), while negative causal relationships were found between SHBG and HBP (MVMR: β=-0.02; 95% CI=-0.04 to -0.00; P = 0.02), TG (MVMR: β=-0.48; 95% CI=-0.70 to -0.26; P < 0.001). Genetically predicted E2 exhibited a negative association with TG (MVMR: β=-1.49; 95% CI=-2.48 to -0.50; P = 0.003). Genetically predicted T was negatively associated with TG (MVMR: β=-0.36; 95% CI=-0.71 to -0.00; P = 0.049) and WC (MVMR: β=-0.13; 95% CI=-0.24 to -0.02; P = 0.02), with inconsistent sensitivity analyses. Additionally, No other causal associations were found.

CONCLUSION

Our study indicates that SHBG is a protective factor for MetS, potentially delaying its onset and progression through improvements in HBP and TG. Furthermore, T and E2 may improve TG levels, with T also reducing WC levels. Importantly, our study provides new insights for the prevention and treatment of MetS.

Sex hormones and neuromyelitis optica spectrum disorder: a bidirectional Mendelian randomization study

BACKGROUND

Females are considered to have an increased susceptibility to neuromyelitis optica spectrum disorder (NMOSD) than males, especially aquaporin-4 (AQP4) antibody positive NMOSD, indicating that sex hormones may be involved in the NMOSD pathogenesis. However, the causality between sex hormones and NMOSD still remains unclear.

METHODS

Based on the genome-wide association study (GWAS) data of three sex hormones (estradiol (E2), progesterone (PROG) and bioavailable testosterone (BAT)), sex hormone-binding globulin (SHBG), age of menarche, age of menopause, and NMOSD (total, AQP4 + and AQP4 -), we performed a two-sample bidirectional Mendelian randomization (MR) study. Sex-stratified GWAS data of E2, PROG, BAT, and SHBG was obtained for gender-specific MR analysis. Causal inferences were based on the inverse variance weighted method, MR-Egger regression, and weighted median method. The reverse MR analysis was also performed to assess the impact of NMOSD on hormone levels.

RESULTS

PROG in females had aggravative effects on NMOSD (P < 0.001), especially AQP4 - NMOSD (P < 0.001). In the reverse MR analysis, total NMOSD was found to decrease the level of BAT (P < 0.001) and increase the level of SHBG (P = 0.001) in females.

CONCLUSION

Findings of this MR analysis revealed mutual causal associations between sex hormones and NMOSD, which provided novel perspectives about the gender-related pathogenesis of NMOSD.

High bioavailable testosterone levels increase the incidence of isolated REM sleep behavior disorder: Results from multivariable and network Mendelian randomization analysis

OBJECTIVES

To explore the causal relationships between sex hormone levels and incidence of isolated REM sleep behavior disorder (iRBD).

METHODS

In our study, we utilized Genome-Wide Association Studies (GWAS) data for iRBD, including 9447 samples with 1061 cases of iRBD provided by the International RBD Study Group. Initially, we conducted a two-sample univariate MR analysis to explore the impact of sex hormone-related indicators on iRBD. This was followed by the application of multivariable MR methods to adjust for other hormone levels and potential confounders. Finally, we undertook a network MR analysis, employing brain structure Magnetic Resonance Imaging (MRI) characteristics as potential mediators, to examine whether sex hormones could indirectly influence the incidence of iRBD by affecting brain structure.

RESULTS

Bioavailable testosterone (BioT) is an independent risk factor for iRBD (Odds Ratio [95 % Confidence Interval] = 2.437 [1.308, 4.539], P = 0.005, corrected-P = 0.020), a finding that remained consistent even after adjusting for other sex hormone levels and potential confounders. Additionally, BioT appears to indirectly increase the risk of iRBD by reducing axial diffusivity and increasing the orientation dispersion index in the left cingulum and cingulate gyrus.

CONCLUSIONS

Our research reveals that elevated levels of BioT contribute to the development of iRBD. However, the specific impact of BioT on different sexes remains unclear. Furthermore, high BioT may indirectly lead to iRBD by impairing normal pathways in the left cingulum and cingulate gyrus and fostering abnormal pathway formation.

The influence of body composition on the response to dynamic stimulation of the endocrine pituitary-testis axis

BACKGROUND

Testosterone treatment is generally not recommended in men with obesity induced low serum testosterone. However, distinguishing this condition from overt testosterone deficiency in men with obesity where treatment should be initiated is a diagnostic challenge and tools to differentiate these conditions are scarce but could be of important clinical relevance.

OBJECTIVES

To investigate the association between body composition and dynamic responses of the pituitary-testis axis in men.

METHODS

Single-center cross-sectional study including 112 healthy men. Participants went through a full biochemical assessment of the pituitary-testis axis, and dynamic stimulatory tests of luteinizing hormone (LH) secretion (gonadotropin-releasing hormone (GnRH)-test) and testosterone secretion (choriogonadotropin (hCG)-test). A subset (N = 78) further had a DXA-scan performed.

RESULTS

A higher body mass index (BMI) was associated with lower basal serum LH (BU = -0.44, 95% CI: -0.88--0.01, p = 0.04). The GnRH-stimulated LH increase was not significantly associated with BMI (BU = -0.10, 95% CI: -0.72-0.51, p = 0.74). Furthermore, a high BMI was associated with low basal testosterone (BU -0.02, 95% CI: -0.03--0.02, p < 0.001), and free testosterone (BU -15.0, 95% CI: -19.9--10.0, p < 0.001) and men with overweight and obesity had significantly lower testosterone (9%, p = 0.003 and 24%, p < 0.001) and free testosterone (25%, p = 0.006 and 50%, p < 0.001) concentrations compared to men with normal weight. The HCG-stimulated testosterone increase was significantly less dependent on BMI compared to the influence of BMI on basal testosterone concentrations (p = 0.04 for the interaction).

CONCLUSIONS

Dynamic sex hormone responses following pituitary-testis axis stimulation were less dependent on BMI, compared to the influence of BMI on basal hormone concentrations and could potentially assist clinical decision making in patients with obesity suspected of testosterone deficiency.

The implications of hormone treatment for cancer risk, screening and treatment in transgender individuals

There is evidence that gender-affirming hormone treatment (GAHT) for transgender individuals modulates their risk for specific malignancies including breast and prostate cancer, and meningiomas. However, there is insufficient data to make precise risk estimates accounting for age and inherited cancer risk. As such, screening recommendations remain broad. Even less evidence exists for best practice in the management of active or historical cancers in the transgender population. Guidance is therefore mainly extrapolated from cisgender populations but with considerations of the significant benefits of GAHT in the face of any hormonal risk. Clinical experience, the multidisciplinary team and shared decision making with the patient are vital in providing person-centred care, while further research is acquired.

Genetic regulation of ovulation rate and multiple births

Ovulation rate in many mammalian species is controlled to regulate the numbers of offspring and maximise reproductive success. Pathways that regulate ovulation rate still respond to genetic and environmental factors and show considerable variation within and between species. Genetic segregation, positional cloning, and association studies have discovered numerous mutations and genetic risk factors that contribute to this variation. Notable among the discoveries has been the role of mutations in bone morphogenetic protein 15 (BMP15 ), growth differentiation factor 9 (GDF9 ) and bone morphogenetic protein receptor type 1B (BMPR1B ) from the intra-ovarian signalling pathway contributing to the evidence that signalling from the oocyte is the key driver in follicle regulation rather than circulating gonadotrophin concentrations. Multiple variants in different domains of BMP15 and GDF9 result in partial or complete loss of function of the proteins providing insights into their functional roles and differential regulation contributing to species differences in ovulation rate. Early success encouraged many more studies in prolific strains of sheep, cattle and goats providing a valuable catalogue of genetic variants of large effect increasing ovulation rate and litter size. More recently, genetic association studies are beginning to identify genetic risk factors with smaller effects. Most genes implicated are from pathways with defined roles in regulation of the ovarian function. However, some genomic regions suggest regulation by novel genes. Continuing genetic and related functional studies will add further to our understanding of the detailed regulation of ovulation rate and litter size with implications for health and animal production systems.

Uncovering the shared genetic components of thyroid disorders and reproductive health

OBJECTIVE

The aim of the study is to map the shared genetic component and relationships between thyroid and reproductive health traits to improve the understanding of the interplay between those domains.

DESIGN

A large-scale genetic analysis of thyroid traits (hyper- and hypothyroidism, and thyroid-stimulating hormone levels) was conducted in up to 743 088 individuals of European ancestry from various cohorts.

METHODS

We evaluated genetic associations using genome-wide association study (GWAS) meta-analysis, GWAS Catalog lookup, gene prioritization, mouse phenotype lookup, and genetic correlation analysis.

RESULTS

GWAS meta-analysis results for thyroid phenotypes showed that 50 lead variants out of 253 (including 5/52 of the novel hits) were linked to reproductive health in previous literature. Genetic correlation analyses revealed significant correlations between hypothyroidism and reproductive phenotypes. The results showed that 31.9% of thyroid-associated genes also had an impact on reproductive phenotypes, with the most affected functions being related to genitourinary tract issues.

CONCLUSIONS

The study discovers novel genetic loci linked to thyroid phenotypes and highlights the shared genetic determinants between thyroid function and reproductive health, providing evidence for the genetic pleiotropy and shared biological mechanisms between these traits in both sexes.

Hormone and reproductive factors and risk of systemic lupus erythematosus: a Mendelian randomized study

Systemic lupus erythematosus (SLE) is an autoimmune and inflammatory disease with a risk associated with hormonal and reproductive factors. However, the potential causal effects between these factors and SLE remain unclear. A two-sample Mendelian randomization study was conducted using the published summary data from the genome-wide association study database. Five independent genetic variants associated with hormonal and reproductive factors were selected as instrumental variables: age at menarche, age at natural menopause, estradiol, testosterone, and follistatin. To estimate the causal relationship between these exposure factors and disease outcome, we employed the inverse-variance weighted, weighted median, and MR-Egger methods. In addition, we carried out multiple sensitivity analyses to validate model assumptions. Inverse variance weighted showed that there was a causal association between circulating follistatin and SLE risk (OR = 1.38, 95% CI 1.03 to 1.86, P = 0.033). However, no evidence was found that correlation between AAM (OR = 1.04, 95% CI 0.77 to 1.40, P = 0.798), ANM (OR = 0.99, 95% CI 0.92 to 1.06, P = 0.721), E2 (OR = 1.40, 95% CI 0.14 to 13.56, P = 0.772), T (OR = 1.25, 95% CI 0.70 to 2.28, P = 0.459), and SLE risk. Our study revealed that elevated circulating follistatin associates with an increased risk of SLE. This finding suggests that the regulatory signals mediated by circulating follistatin may provide a potential mechanism relevant to the treatment of SLE.

Association between levels of sex hormones and risk of multiple sclerosis: a mendelian randomization study

BACKGROUND

This research aimed to examine the causal connections between multiple sclerosis (MS) and a range of sex hormone-related traits, such as bioavailable testosterone (BT), sex hormone-binding globulin (SHBG), testosterone, and estradiol (E2).

METHODS

A bidirectional two-sample Mendelian randomization (MR) analysis using summary statistics from genome-wide association studies (GWAS) was conducted to investigate the relationship between sex hormone-related traits and MS. Moreover, the Inverse-variance weighted (IVW) method was employed as the primary analysis approach.

RESULTS

The MR analysis, using the IVW method, found a significant correlation between genetically determined SHBG levels and MS (OR = 1.634, 95% CI: 1.029-2.599, p = 0.038). Similarly, the reverse MR analysis suggested a causal link between MS and SHBG (OR = 1.005, 95% CI: 1.001-1.009, P = 0.003). However, no association was observed between MS risk and E2, testosterone, or BT levels.

CONCLUSION

Our MR analysis demonstrated that genetically predicted higher SHBG may be positively correlated with the risk of MS. Moreover, the role of SHBG in MS could be further investigated.

The GG genotype of rs743572 in CYP17A1 gene regulating the decrease of T/E ratio can be an independent risk factor for MetS-BPH: a retrospective cohort study

PURPOSE

To confirm if the CYP17A1 gene regulates the ratio of T/E leading to MetS-BPH.

METHODS

824 men, aged 47-88 years, were recruited into this study through consecutive routine physical examination programs and long-term outpatient screening. Several parameters, including SNPs of CYP17A1 gene, total testosterone, estradiol, and the ratio of total testosterone to estradiol (T/E) were obtained for each participant. Based on the diagnosis of BPH, MetS, and MetS-BPH, the participants were divided into BPH and non-BPH groups, MetS and non-MetS groups, and MetS-BPH and non-MetS-BPH groups. Values of the obtained parameters were evaluated using one-way analysis of variance, Student's t-test, Chi-squared test, and logistic regression analysis.

RESULTS

SNPs of the CYP17A1 gene, including the rs743572 genotypes (GG, GA, and AA), rs3781287 genotypes (GG, GT, TT), and rs4919686 genotypes (CC, CA, and AA), were present in every group. Only the GG genotype of rs743572 was independently associated with BPH (OR = 5.868, 95% CI: 3.363-7.974, P < 0.001), MetS (OR = 7.228, 95% CI: 3.925-11.331, P < 0.001), and MetS-BPH (OR = 3.417, 95% CI: 1.783-5.266, P < 0.001) after adjusting for age. In the population of genotype GG of rs743572, the decrease in T/E ratio was an independent risk factor for BPH (OR = 839.756, 95% CI: 36.978-1334.263, P = 0.001), MetS (OR = 376.988, 95% CI: 12.980-488.976, P < 0.003), and MetS-BPH (OR = 388.236, 95% CI: 24.869-495.363, P = 0.003).

CONCLUSION

The GG genotype of rs743572 in CYP17A1 gene regulating the decrease of T/E ratio can be an independent risk factor for MetS-BPH populations.

TRIAL REGISTRATION NUMBER

ChiCTR2200057632 "retrospectively registered".

DATE OF REGISTRATION

March 15, 2022 "retrospectively registered".

Chromosome X-Wide Common Variant Association Study (XWAS) in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) displays a notable male bias in prevalence. Research into rare (<0.1) genetic variants on the X chromosome has implicated over 20 genes in ASD pathogenesis, such as MECP2, DDX3X, and DMD. The "female protective effect" in ASD suggests that females may require a higher genetic burden to manifest similar symptoms as males, yet the mechanisms remain unclear. Despite technological advances in genomics, the complexity of the biological nature of sex chromosomes leave them underrepresented in genome-wide studies. Here, we conducted an X chromosome-wide association study (XWAS) using whole-genome sequencing data from 6,873 individuals with ASD (82% males) across Autism Speaks MSSNG, Simons Simplex Cohort SSC, and Simons Foundation Powering Autism Research SPARK, alongside 8,981 population controls (43% males). We analyzed 418,652 X-chromosome variants, identifying 59 associated with ASD (p-values 7.9×10-6 to 1.51×10-5), surpassing Bonferroni-corrected thresholds. Key findings include significant regions on chrXp22.2 (lead SNP=rs12687599, p=3.57×10-7) harboring ASB9/ASB11, and another encompassing DDX53/PTCHD1-AS long non-coding RNA (lead SNP=rs5926125, p=9.47×10-6). When mapping genes within 10kb of the 59 most significantly associated SNPs, 91 genes were found, 17 of which yielded association with ASD (GRPR, AP1S2, DDX53, HDAC8, PCDH19, PTCHD1, PCDH11X, PTCHD1-AS, DMD, SYAP1, CNKSR2, GLRA2, OFD1, CDKL5, GPRASP2, NXF5, SH3KBP1). FGF13 emerged as a novel X-linked ASD candidate gene, highlighted by sex-specific differences in minor allele frequencies. These results reveal significant new insights into X chromosome biology in ASD, confirming and nominating genes and pathways for further investigation.

Sex Hormones and Chronic Obstructive Pulmonary Disease: A Cross-Sectional Study and Mendelian Randomization Analysis

Background

Sex steroid hormones, including testosterone and estradiol, play significant roles in various aspects of pulmonary health and diseases. However, although there were a few studies trying to link sex hormones with COPD, their effect remained limited due to small sample size and insufficient causal results. This study aims to investigate the association between sex hormones and chronic obstructive pulmonary disease (COPD) based on the National Health and Nutrition Examination Survey (NHANES) database and evaluate causality via a two-sample Mendelian randomization (MR).

Methods

Data from NHANES 2013-2016 were enrolled for the cross-sectional study. The association between sex hormones and COPD was evaluated via multivariable logistic regression. Sex-stratified analysis, subgroup analyses and interaction tests were performed to further evaluate the correlation. For MR analysis, data were collected from genome-wide association studies and FinnGen datasets. The inverse-variance-weighted (IVW) approach, along with four other approaches, was applied in the analysis. Further sensitivity analysis was conducted to assess the existence of pleiotropy and heterogeneity.

Results

7,617 eligible participants were enrolled in the cross-sectional analysis. Negative associations were observed in both testosterone-COPD (OR 0.770, 95% CI 0.626, 0.948, p = 0.018) and estradiol-COPD (OR 0.794, 95% CI 0.688, 0.915, p = 0.005) relationships after covariate adjustments. However, the results from IVW-MR analysis showed that no causal relationship was observed in either the testosterone-COPD (OR 0.83, 95% CI 0.53, 1.29, p = 0.407) or estradiol-COPD (OR 0.74, 95% CI 0.23, 2.38, p = 0.616) relationship, which was also supported by the other four approaches (all p values > 0.05).

Conclusion

Although a significant negative association was observed between sex hormones and COPD, the results of MR analysis did not support the causality of this relationship. Our study suggested that sex hormones may indirectly rather than directly affect the development of COPD via potential covariates, which warranted further investigations.

Prostate Risk and Monitoring During Testosterone Replacement Therapy

ABSTRACT

Men with hypogonadism have reduced risk of prostate cancer mortality; whether testosterone treatment increases the risk of prostate safety events in men with hypogonadism remains controversial. Several studies including 4 larger randomized trials-the Testosterone Trials, TEstosterone and Atherosclerosis Progression in Aging Men (TEAAM) trial, Testosterone for Diabetes Mellitus trial, and Testosterone Replacement therapy for Assessment of long-term Vascular Events and efficacy ResponSE in hypogonadal men (TRAVERSE) trial-treated men with testosterone or placebo for 1 year or longer and reported prospectively ascertained prostate safety data. The TRAVERSE Trial, because of its large size, longer duration, and adjudication of prostate events, has provided comprehensive data on the risk of adverse prostate events during testosterone replacement therapy (TRT). Among men with hypogonadism, carefully screened to exclude those at high risk of prostate cancer, the incidences of high-grade or any prostate cancer, acute urinary retention, surgical procedure for benign prostatic hyperplasia, prostate biopsy, or new pharmacologic therapy for lower urinary tract symptoms were low and did not differ between the testosterone and placebo groups. Testosterone did not worsen lower urinary tract symptoms. TRT was associated with a greater increase in prostate-specific antigen than placebo in the first year of treatment.

CONCLUSION

Testosterone treatment of men with hypogonadism, screened to exclude those at high risk of prostate cancer, is associated with low risk of adverse prostate events. Baseline evaluation of prostate cancer risk and a standardized monitoring plan can minimize the risk of unnecessary prostate biopsy while enabling the detection of high-grade prostate cancers in men receiving TRT.

A scalable and robust variance components method reveals insights into the architecture of gene-environment interactions underlying complex traits

Understanding the contribution of gene-environment interactions (GxE) to complex trait variation can provide insights into disease mechanisms, explain sources of heritability, and improve genetic risk prediction. While large biobanks with genetic and deep phenotypic data hold promise for obtaining novel insights into GxE, our understanding of GxE architecture in complex traits remains limited. We introduce a method to estimate the proportion of trait variance explained by GxE (GxE heritability) and additive genetic effects (additive heritability) across the genome and within specific genomic annotations. We show that our method is accurate in simulations and computationally efficient for biobank-scale datasets. We applied our method to common array SNPs (MAF ≥1%), fifty quantitative traits, and four environmental variables (smoking, sex, age, and statin usage) in unrelated white British individuals in the UK Biobank. We found 68 trait-E pairs with significant genome-wide GxE heritability (p<0.05/200) with a ratio of GxE to additive heritability of ≈6.8% on average. Analyzing ≈8 million imputed SNPs (MAF ≥0.1%), we documented an approximate 28% increase in genome-wide GxE heritability compared to array SNPs. We partitioned GxE heritability across minor allele frequency (MAF) and local linkage disequilibrium (LD) values, revealing that, like additive allelic effects, GxE allelic effects tend to increase with decreasing MAF and LD. Analyzing GxE heritability near genes highly expressed in specific tissues, we find significant brain-specific enrichment for body mass index (BMI) and basal metabolic rate in the context of smoking and adipose-specific enrichment for waist-hip ratio (WHR) in the context of sex.

The retrotransposon-derived capsid genes PNMA1 and PNMA4 maintain reproductive capacity

The human genome contains 24 gag-like capsid genes derived from deactivated retrotransposons conserved among eutherians. Although some of their encoded proteins retain the ability to form capsids and even transfer cargo, their fitness benefit has remained elusive. Here we show that the gag-like genes PNMA1 and PNMA4 support reproductive capacity during aging. Analysis of donated human ovaries shows that expression of both genes declines normally with age, while several PNMA1 and PNMA4 variants identified in genome-wide association studies are causally associated with low testosterone, altered puberty onset, or obesity. Six-week-old mice lacking either Pnma1 or Pnma4 are indistinguishable from wild-type littermates, but by six months the mutant mice become prematurely subfertile, with precipitous drops in sex hormone levels, gonadal atrophy, and abdominal obesity; overall they produce markedly fewer offspring than controls. These findings expand our understanding of factors that maintain human reproductive health and lend insight into the domestication of retrotransposon-derived genes.

Androgen receptor-mediated pharmacogenomic expression quantitative trait loci: implications for breast cancer response to AR-targeting therapy

BACKGROUND

Endocrine therapy is the most important treatment modality of breast cancer patients whose tumors express the estrogen receptor α (ERα). The androgen receptor (AR) is also expressed in the vast majority (80-90%) of ERα-positive tumors. AR-targeting drugs are not used in clinical practice, but have been evaluated in multiple trials and preclinical studies.

METHODS

We performed a genome-wide study to identify hormone/drug-induced single nucleotide polymorphism (SNP) genotype - dependent gene-expression, known as PGx-eQTL, mediated by either an AR agonist (dihydrotestosterone) or a partial antagonist (enzalutamide), utilizing a previously well characterized lymphoblastic cell line panel. The association of the identified SNPs-gene pairs with breast cancer phenotypes were then examined using three genome-wide association (GWAS) studies that we have published and other studies from the GWAS catalog.

RESULTS

We identified 13 DHT-mediated PGx-eQTL loci and 23 Enz-mediated PGx-eQTL loci that were associated with breast cancer outcomes post ER antagonist or aromatase inhibitors (AI) treatment, or with pharmacodynamic (PD) effects of AIs. An additional 30 loci were found to be associated with cancer risk and sex-hormone binding globulin levels. The top loci involved the genes IDH2 and TMEM9, the expression of which were suppressed by DHT in a PGx-eQTL SNP genotype-dependent manner. Both of these genes were overexpressed in breast cancer and were associated with a poorer prognosis. Therefore, suppression of these genes by AR agonists may benefit patients with minor allele genotypes for these SNPs.

CONCLUSIONS

We identified AR-related PGx-eQTL SNP-gene pairs that were associated with risks, outcomes and PD effects of endocrine therapy that may provide potential biomarkers for individualized treatment of breast cancer.

Association between sex hormones and gout: An analysis of the UK Biobank cohort

OBJECTIVES

To investigate the associations between sex hormones and gout.

METHODS

A total of 448,836 individuals free of gout at baseline were included from the UK Biobank. Cox regression models were used to estimate hazard ratios (HRs) for gout. Besides, we investigated the causal relationship between bioavailable testosterone (BAT) and gout using mendelian randomization (MR).

RESULTS

There were differential effects in different testosterone active states in gout. One-unit higher log-transformed total testosterone (TT) was associated with a 52 % [95 % CI, 0.39-0.58] lower risk of gout in males. In contrast, free testosterone (FT) and BAT were associated with a 74 % [95 % CI, 1.38-2.20] and a 78 % [95 % CI, 1.41-2.25] higher risk of gout in males respectively. For MR, the weighted median [OR, 1.70; 95 % CI, 1.14-2.56;] and inverse variance-weighted [OR, 1.25; 95 % CI, 0.96-1.62; P = 0.09] method revealed significant and approximately significant positive effect of genetic liability to BAT levels on the risk of gout respectively.

CONCLUSIONS

Sex hormones were potentially associated with gout. Notably, we were the first to explore different testosterone states on gout and found that FT and BAT may increase the risk of gout in males, which is opposite to TT. And the former are active states of androgens, may be more accurately reflect the association between androgens and gout.

SHBG, Free Testosterone, and Type 2 Diabetes Risk in Middle-aged African Men: A Longitudinal Study

Objectives

To investigate longitudinal changes in SHBG and free testosterone (free T) levels among Black middle-aged African men, with and without coexistent HIV, and explore associations with incident dysglycaemia and measures of glucose metabolism.

Design

This longitudinal study enrolled 407 Black South African middle-aged men, comprising primarily 322 men living without HIV (MLWOH) and 85 men living with HIV (MLWH), with normal fasting glucose at enrollment. Follow-up assessments were conducted after 3.1 ± 1.5 years.

Methods

At baseline and follow-up, SHBG, albumin, and total testosterone were measured and free T was calculated. An oral glucose tolerance test at follow-up determined dysglycaemia (impaired fasting glucose, impaired glucose tolerance, type 2 diabetes) and glucose metabolism parameters including insulin sensitivity (Matsuda index), insulin resistance (homeostasis model assessment of insulin resistance), and beta(β)-cell function (disposition index). The primary analysis focussed on MLWOH, with a subanalysis on MLWH to explore whether associations in MLWOH differed from MLWH.

Results

The prevalence of dysglycaemia at follow-up was 17% (n = 55) in MLWOH. Higher baseline SHBG was associated with a lower risk of incident dysglycaemia (odds ratio 0.966; 95% confidence interval 0.945-0.987) and positively associated with insulin sensitivity (β = 0.124, P < .001) and β-cell function (β = 0.194, P = .001) at follow-up. Free T did not predict dysglycaemia. In MLWH, dysglycaemia prevalence at follow-up was 12% (n = 10). Neither baseline SHBG nor free T were associated with incident dysglycaemia and glucose metabolism parameters in MLWH.

Conclusion

SHBG levels predict the development of dysglycaemia in middle-aged African men but do not exhibit the same predictive value in MLWH.

Disentangling the relationships of body mass index and circulating sex hormone concentrations in mammographic density using Mendelian randomization

PURPOSE

Mammographic density phenotypes, adjusted for age and body mass index (BMI), are strong predictors of breast cancer risk. BMI is associated with mammographic density measures, but the role of circulating sex hormone concentrations is less clear. We investigated the relationship between BMI, circulating sex hormone concentrations, and mammographic density phenotypes using Mendelian randomization (MR).

METHODS

We applied two-sample MR approaches to assess the association between genetically predicted circulating concentrations of sex hormones [estradiol, testosterone, sex hormone-binding globulin (SHBG)], BMI, and mammographic density phenotypes (dense and non-dense area). We created instrumental variables from large European ancestry-based genome-wide association studies and applied estimates to mammographic density phenotypes in up to 14,000 women of European ancestry. We performed analyses overall and by menopausal status.

RESULTS

Genetically predicted BMI was positively associated with non-dense area (IVW: β = 1.79; 95% CI = 1.58, 2.00; p = 9.57 × 10-63) and inversely associated with dense area (IVW: β = - 0.37; 95% CI = - 0.51,- 0.23; p = 4.7 × 10-7). We observed weak evidence for an association of circulating sex hormone concentrations with mammographic density phenotypes, specifically inverse associations between genetically predicted testosterone concentration and dense area (β = - 0.22; 95% CI = - 0.38, - 0.053; p = 0.009) and between genetically predicted estradiol concentration and non-dense area (β =  - 3.32; 95% CI = - 5.83, - 0.82; p = 0.009), although results were not consistent across a range of MR approaches.

CONCLUSION

Our findings support a positive causal association between BMI and mammographic non-dense area and an inverse association between BMI and dense area. Evidence was weaker and inconsistent for a causal effect of circulating sex hormone concentrations on mammographic density phenotypes. Based on our findings, associations between circulating sex hormone concentrations and mammographic density phenotypes are weak at best.

Folliculogenesis and steroidogenesis alterations after chronic exposure to a human-relevant mixture of environmental toxicants spare the ovarian reserve in the rabbit model

BACKGROUND

Industrial progress has led to the omnipresence of chemicals in the environment of the general population, including reproductive-aged and pregnant women. The reproductive function of females is a well-known target of endocrine-disrupting chemicals. This function holds biological processes that are decisive for the fertility of women themselves and for the health of future generations. However, insufficient research has evaluated the risk of combined mixtures on this function. This study aimed to assess the direct impacts of a realistic exposure to eight combined environmental toxicants on the critical process of folliculogenesis.

METHODS

Female rabbits were exposed daily and orally to either a mixture of eight environmental toxicants (F group) or the solvent mixture (NE group, control) from 2 to 19 weeks of age. The doses were computed from previous toxicokinetic data to reproduce steady-state serum concentrations in rabbits in the range of those encountered in pregnant women. Ovarian function was evaluated through macroscopic and histological analysis of the ovaries, serum hormonal assays and analysis of the expression of steroidogenic enzymes. Cellular dynamics in the ovary were further investigated with Ki67 staining and TUNEL assays.

RESULTS

F rabbits grew similarly as NE rabbits but exhibited higher total and high-density lipoprotein (HDL) cholesterol levels in adulthood. They also presented a significantly elevated serum testosterone concentrations, while estradiol, progesterone, AMH and DHEA levels remained unaffected. The measurement of gonadotropins, androstenedione, pregnenolone and estrone levels yielded values below the limit of quantification. Among the 7 steroidogenic enzymes tested, an isolated higher expression of Cyp19a1 was measured in F rabbits ovaries. Those ovaries presented a significantly greater density/number of antral and atretic follicles and larger antral follicles without any changes in cellular proliferation or DNA fragmentation. No difference was found regarding the count of other follicle stages notably the primordial stage, the corpora lutea or AMH serum levels.

CONCLUSION

Folliculogenesis and steroidogenesis seem to be subtly altered by exposure to a human-like mixture of environmental toxicants. The antral follicle growth appears promoted by the mixture of chemicals both in their number and size, potentially explaining the increase in atretic antral follicles. Reassuringly, the ovarian reserve estimated through primordial follicles number/density and AMH is spared from any alteration. The consequences of these changes on fertility and progeny health have yet to be investigated.

Genetically evaluating the causal role of peripheral immune cells in colorectal cancer: a two-sample Mendelian randomization study

BACKGROUND

Investigating novel therapeutic strategies for colorectal cancer (CRC) is imperative. However, there is limited research on the use of drugs to target peripheral blood immune cells in this context. To address this gap, we performed a two-sample Mendelian randomization (MR) analysis to identify potential therapeutic targets for CRC.

METHODS

We applied two-sample MR to identify the causal relationship between peripheral blood immune cells and CRC. GWAS data were obtained from the IEU OPEN GWAS project. Based on the implications from the MR results, we conducted a comprehensive database search and genetic analysis to explore potential underlying mechanisms. We predicted miRNAs for each gene and employed extensive research for potential therapeutic applications.

RESULTS

We have identified causal associations between two peripheral immune cells and colorectal cancer. Activated & resting Treg %CD4 + cell was positively associated with the risks of CRC, while DN (CD4-CD8-) %leukocyte cell exhibited a protective role in tumor progression. NEK7 (NIMA related kinase 7) and LHX9 (LIM homeobox 9) expressed in Treg cells were positively associated with CRC risks and may play a vital role in carcinogenesis.

CONCLUSIONS

This study identified causal relationship between peripheral immune cell and CRC. Treg and DN T cells were implicated to own promoting and inhibiting effects on CRC progression respectively. NEK7 and LHX9 in Treg cells were identified as potential biotarget for antitumor therapies.

A Mendelian randomization study between metabolic syndrome and its components with prostate cancer

Previous research has produced inconsistent findings concerning the connection between metabolic syndrome and prostate cancer. It is challenging for observational studies to establish a conclusive causal relationship between the two. However, Mendelian randomization can provide stronger evidence of causality in this context. To examine the causal link between a metabolic composite and its components with prostate cancer, we performed a two-sample Mendelian randomization (MR) study utilizing aggregated data from genome-wide association studies, followed by meta-analyses. In our study, we employed inverse variance weighting as the primary method for MR analysis. Additionally, we assessed potential sources of heterogeneity and horizontal pleiotropy through the Cochran's Q test and MR-Egger regression. Moreover, we used multivariate MR to determine whether smoking versus alcohol consumption had an effect on the outcomes. We found no causal relationship between metabolic syndrome and its components and prostate cancer(MetS, odds ratio [OR] = 0.95, 95% confidence interval [CI] = 0.738-1.223, p = 0.691; TG, [OR] = 1.02, 95%[CI] = 0.96-1.08, p = 0.59); HDL, [OR] = 1.02, 95% [CI] = 0.97-1.07, p = 0.47; DBP, [OR] = 1.00, 95%[CI] = 0.99-1.01, p = 0.87; SBP, [OR] = 1.00, 95%[CI] = 0.99-1.00, p = 0.26; FBG [OR] = 0.92, 95%[CI] = 0.81-1.05, p = 0.23; WC, [OR] = 0.93, 95%[CI] = 0.84-1.03, p = 0.16). Finally, the MVMR confirms that the metabolic syndrome and its components are independent of smoking and alcohol consumption in prostate cancer. We didn't find significant evidence to determine a causal relationship between the metabolic syndrome and its components and prostate cancer through MR analysis. Further research is necessary to explore the potential pathogenesis between the two diseases.

Genetically predicted high sex hormone binding globulin was associated with decreased risk of polycystic ovary syndrome

BACKGROUND

Previous observational studies have indicated an inverse correlation between circulating sex hormone binding globulin (SHBG) levels and the incidence of polycystic ovary syndrome (PCOS). Nevertheless, conventional observational studies may be susceptible to bias. Consequently, we conducted a two-sample Mendelian randomization (MR) investigation to delve deeper into the connection between SHBG levels and the risk of PCOS.

METHODS

We employed single-nucleotide polymorphisms (SNPs) linked to serum SHBG levels as instrumental variables (IVs). Genetic associations with PCOS were derived from a meta-analysis of GWAS data. Our primary analytical approach relied on the inverse-variance weighted (IVW) method, complemented by alternative MR techniques, including simple-median, weighted-median, MR-Egger regression, and MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) testing. Additionally, sensitivity analyses were conducted to assess the robustness of the association.

RESULTS

We utilized 289 SNPs associated with serum SHBG levels, achieving genome-wide significance, as instrumental variables (IVs). Our MR analyses revealed that genetically predicted elevated circulating SHBG concentrations were linked to a reduced risk of PCOS (odds ratio (OR) = 0.56, 95% confidence interval (CI): 0.39-0.78, P = 8.30 × 10-4) using the IVW method. MR-Egger regression did not detect any directional pleiotropic effects (P intercept = 0.626). Sensitivity analyses, employing alternative MR methods and IV sets, consistently reaffirmed our results, underscoring the robustness of our findings.

CONCLUSIONS

Through a genetic epidemiological approach, we have substantiated prior observational literature, indicating a potential causal inverse relationship between serum SHBG concentrations and PCOS risk. Nevertheless, further research is needed to elucidate the underlying mechanism of SHBG in the development of PCOS.

Multivariate genetic architecture reveals testosterone-driven sexual antagonism in contemporary humans

Sex difference (SD) is ubiquitous in humans despite shared genetic architecture (SGA) between the sexes. A univariate approach, i.e., studying SD in single traits by estimating genetic correlation, does not provide a complete biological overview, because traits are not independent and are genetically correlated. The multivariate genetic architecture between the sexes can be summarized by estimating the additive genetic (co)variance across shared traits, which, apart from the cross-trait and cross-sex covariances, also includes the cross-sex-cross-trait covariances, e.g., between height in males and weight in females. Using such a multivariate approach, we investigated SD in the genetic architecture of 12 anthropometric, fat depositional, and sex-hormonal phenotypes. We uncovered sexual antagonism (SA) in the cross-sex-cross-trait covariances in humans, most prominently between testosterone and the anthropometric traits - a trend similar to phenotypic correlations. 27% of such cross-sex-cross-trait covariances were of opposite sign, contributing to asymmetry in the SGA. Intriguingly, using multivariate evolutionary simulations, we observed that the SGA acts as a genetic constraint to the evolution of SD in humans only when selection is sexually antagonistic and not concordant. Remarkably, we found that the lifetime reproductive success in both the sexes shows a positive genetic correlation with anthropometric traits, but not with testosterone. Moreover, we demonstrated that genetic variance is depleted along multivariate trait combinations in both the sexes but in different directions, suggesting absolute genetic constraint to evolution. Our results indicate that testosterone drives SA in contemporary humans and emphasize the necessity and significance of using a multivariate framework in studying SD.

Hormonal regulation in diabetes: Special emphasis on sex hormones and metabolic traits

Diabetes constitutes a significant global public health challenge that is rapidly reaching epidemic proportions. Among the non-communicable diseases, the incidence of diabetes is rising at an alarming rate. The International Diabetes Federation has documented a 9.09% prevalence of diabetes among individuals aged between 20 and 79 years. The interplay of gonadal hormones and gender differences is critical in regulating insulin sensitivity and glucose tolerance, and this dynamic is particularly crucial because of the escalating incidence of diabetes. Variations in insulin sensitivity are observed across genders, levels of adiposity, and age groups. Both estrogen and testosterone are seen to influence glucose metabolism and insulin sensitivity. This chapter surveys the present knowledge of sex differences, sex hormones, and chromosomes on insulin imbalance and diabetes development. It further highlights the influence of metabolic traits in diabetes and changes in sex hormones during diabetic pregnancy. Notably, even stressful lifestyles have been acknowledged to induce hormonal imbalances. Furthermore, it discusses the potential of hormonal therapy to help stabilize sex hormones in diabetic individuals and focuses on the most recent research investigating the correlation between sex hormones and diabetes.

The impact of cannabis use on erectile dysfunction and sex hormones: a Mendelian randomization analysis

Previous study has highlighted an association between cannabis use (CU) and an increased risk of erectile dysfunction (ED), potentially due to indirect effects on sex hormonal balance. However, the evidence remains controversial, and the causal relationship is unclear. This study utilized genome-wide association study (GWAS) data to investigate the causal relationships between cannabis use disorder (CUD), lifetime cannabis use (LCU), and ED, as well as levels of sex hormones including estradiol (E2), bioavailable testosterone (BT), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) through Mendelian randomization (MR) analysis. The primary method of analysis was the inverse variance weighted (IVW) method. Data from the FinnGen and UK Biobank were used for replication and meta-analysis. The results indicated no causal relationship between genetically predicted CUD (OR = 0.97, 95% CI 0.87-1.10, P = 0.66) and LCU (OR = 1.13, 95% CI 0.84-1.50, P = 0.42) with the risk of ED. The meta-analysis provided consistent evidence (P > 0.05). No causal relationships were found between CUD and LCU with E2(CUD: β = 0.00, 95% CI 0.00-0.01, P = 0.37; LCU: β = 0.00, 95% CI -0.02-0.01, P = 0.62), BT (CUD: β = 0.00, 95% CI -0.03-0.02, P = 0.90; LCU: β = 0.02, 95% CI -0.04-0.09, P = 0.46), FSH (CUD: β = 0.01, 95% CI -0.18-0.20, P = 0.92; LCU: β = 0.01, 95% CI -0.44-0.47, P = 0.95), and LH (CUD: β = 0.01, 95% CI -0.18-0.21, P = 0.90; LCU: β = 0.13, 95% CI -0.22-0.49, P = 0.46). Sensitivity analyses detected no evidence of horizontal pleiotropy or heterogeneity, ensuring the robustness of the results. In conclusion, this MR analysis did not provide evidence supporting a causal relationship between CU and ED or sex hormone levels.

Causal Relationship between Sex Hormone-Binding Globulin and Risk of Neuroblastoma: A Bidirectional Two-Sample Mendelian Randomization Study

BACKGROUND

The causal relationship between sex hormone-binding globulin (SHBG) and neuroblastoma remains unknown. This study aimed to explore the causality between SHBG and the risk of neuroblastoma using bidirectional two-sample Mendelian randomization (MR) study.

METHODS

Instrumental variables associated with SHBG were obtained from the genome-wide association study (GWAS) of European containing 214,989 females and 185,221 males from the UK Biobank. Summary-level data for neuroblastoma were derived from the IEU OpenGWAS project with 1,627 patients and 3,254 controls. The inverse-variance weighted (IVW) method served as the primary analytic tool.

RESULTS

The IVW method revealed a significant positive causal relationship between male SHBG and the risk of neuroblastoma [OR, 2.169; 95% confidence interval (CI), 1.207-3.897; P = 0.010]. Conversely, female SHBG showed no significant causal link with neuroblastoma (IVW OR, 1.004; 95% CI, 0.542-1.860; P = 0.990). No significant reverse causality was detected. Sensitivity analyses validated these findings.

CONCLUSIONS

Elevated SHBG levels in males, but not in females, can causally increase the risk of neuroblastoma. This gender-specific effect indicates a potential differential role of SHBG in the etiology of neuroblastoma. Further research is needed to elucidate the underlying mechanisms of this gender disparity. Monitoring SHBG levels, especially in males, could be pivotal in neuroblastoma risk assessment and management.

IMPACT

This study highlights a novel gender-specific aspect in the risk of neuroblastoma, emphasizing the potential role of male SHBG levels in neuroblastoma incidence, and sets the stage for targeted preventative strategies and further investigation into gender-based biological mechanisms.

Effects of Testosterone in Mediating the Relationship Between Daytime Napping and Osteoporosis in European Populations: A Mendelian Randomization Study

We aimed to explore the causal effect of daytime napping on the risk of osteoporosis and the mediation role of testosterone in explaining this relationship. Summary data for Mendelian randomization (MR) analysis were obtained from the IEU OpenGWAS database. Univariable MR(UVMR) analysis and multiple sensitivity analyses were applied to explore the casual relationship between daytime napping and bone mineral density (BMD)/osteoporosis. We also conducted multivariable Mendelian randomization (MVMR) analysis to evaluate the correlation between testosterone-associated single-nucleotide variations and BMD/osteoporosis. Then, mediation analysis was performed to explore whether the association between daytime napping and BMD/osteoporosis was mediated via testosterone. Genetically predicted daytime napping was significantly associated with femoral neck BMD (β [95% CI]: 0.2573 [0.0487, 0.4660]; P = 0.0156), lumbar spine BMD (β [95% CI]: 0.2526 [0.0211, 0.4840]; P = 0.0324), and osteoporosis (OR [95% CI]: 0.5063 [0.2578, 0.9942]; P = 0.0481). β and 95%CIs indicate the standard deviation (SD) unit of BMD increase per category increase in daytime napping. OR and 95%CIs represent the change in the odds ratio of osteoporosis per category increase in daytime napping. We observed a potentially causal effect of more frequent daytime napping on higher BMD and a lower risk of osteoporosis. Daytime napping was causally associated with a higher level of bioavailable testosterone (β [95% CI]: 0.1397 [0.0619, 0.2175]; P = 0.0004). β and 95%CIs represent the change in the SD of testosterone per category increase in daytime napping. Furthermore, the causal effects of daytime napping on BMD/osteoporosis were partly mediated by bioavailable testosterone. Daytime napping can efficiently increase BMD and reduce the risk of osteoporosis, and testosterone plays a key mediating role in this process.

Estimating causality between smoking and abdominal obesity by Mendelian randomization

BACKGROUND AND AIMS

Smokers tend to have a lower body weight than non-smokers, but also more abdominal fat. It remains unclear whether or not the relationship between smoking and abdominal obesity is causal. Previous Mendelian randomization (MR) studies have investigated this relationship by relying upon a single genetic variant for smoking heaviness. This approach is sensitive to pleiotropic effects and may produce imprecise causal estimates. We aimed to estimate causality between smoking and abdominal obesity using multiple genetic instruments.

DESIGN

MR study using causal analysis using summary effect estimates (CAUSE) and latent heritable confounder MR (LHC-MR) methods that instrument smoking using genome-wide data, and also two-sample MR (2SMR) methods.

SETTING

Genome-wide association studies (GWAS) summary statistics from participants of European ancestry, obtained from the GWAS and Sequencing Consortium of Alcohol and Nicotine use (GSCAN), Genetic Investigation of Anthropometric Traits (GIANT) Consortium and the UK Biobank.

PARTICIPANTS

We used GWAS results for smoking initiation (n = 1 232 091), life-time smoking (n = 462 690) and smoking heaviness (n = 337 334) as exposure traits, and waist-hip ratio (WHR) and waist and hip circumferences (WC and HC) (n up to 697 734), with and without adjustment for body mass index (adjBMI), as outcome traits.

MEASUREMENTS

Smoking initiation, life-time smoking, smoking heaviness, WHR, WC, HC, WHRadjBMI, WCadjBMI and HCadjBMI.

FINDINGS

Both CAUSE and LHC-MR indicated a positive causal effect of smoking initiation on WHR (0.13 [95% confidence interval (CI) = 0.10, 0.16 and 0.49 (0.41, 0.57), respectively] and WHRadjBMI (0.07 (0.03, 0.10) and 0.31 (0.26, 0.37). Similarly, they indicated a positive causal effect of life-time smoking on WHR [0.35 (0.29, 0.41) and 0.44 (0.38, 0.51)] and WHRadjBMI [0.18 (0.13, 0.24) and 0.26 (0.20, 0.31)]. In follow-up analyses, smoking particularly increased visceral fat. There was no evidence of a mediating role by cortisol or sex hormones.

CONCLUSIONS

Smoking initiation and higher life-time smoking may lead to increased abdominal fat distribution. The increase in abdominal fat due to smoking is characterized by an increase in visceral fat. Thus, efforts to prevent and cease smoking can have the added benefit of reducing abdominal fat.

MRAS in coronary artery disease-Unchartered territory

Genome-wide association studies (GWAS) have identified coronary artery disease (CAD) susceptibility locus on chromosome 3q22.3. This locus contains a cluster of several genes that includes muscle rat sarcoma virus (MRAS). Common MRAS variants are also associated with CAD causing risk factors such as hypertension, dyslipidemia, obesity, and type II diabetes. The MRAS gene is an oncogene that encodes a membrane-bound small GTPase. It is involved in a variety of signaling pathways, regulating cell differentiation and cell survival (mitogen-activated protein kinase [MAPK]/extracellular signal-regulated kinase and phosphatidylinositol 3-kinase) as well as acute phase response signaling (tumor necrosis factor [TNF] and interleukin 6 [IL6] signaling). In this review, we will summarize the role of genetic MRAS variants in the etiology of CAD and its comorbidities with the focus on tissue distribution of MRAS isoforms, cell type/tissue specificity, and mode of action of single nucleotide variants in MRAS associated complex traits. Finally, we postulate that CAD risk variants in the MRAS locus are specific to smooth muscle cells and lead to higher levels of MRAS, particularly in arterial and cardiac tissue, resulting in MAPK-dependent tissue hypertrophy or hyperplasia.

Gut Microbiome and Polycystic Ovary Syndrome: Interplay of Associated Microbial-Metabolite Pathways and Therapeutic Strategies

Polycystic ovary syndrome (PCOS) is a multifaceted disease with an intricate etiology affecting reproductive-aged women. Despite attempts to unravel the pathophysiology, the molecular mechanism of PCOS remains unknown. There are no effective or suitable therapeutic strategies available to ameliorate PCOS; however, the symptoms can be managed. In recent years, a strong association has been found between the gut microbiome and PCOS, leading to the formulation of novel ideas on the genesis and pathological processes of PCOS. Further, gut microbiome dysbiosis involving microbial metabolites may trigger PCOS symptoms via many mechanistic pathways including those associated with carbohydrates, short-chain fatty acids, lipopolysaccharides, bile acids, and gut-brain axis. We present the mechanistic pathways of PCOS-related microbial metabolites and therapeutic opportunities available to treat PCOS, such as prebiotics, probiotics, and fecal microbiota therapy. In addition, the current review highlights the emerging treatment strategies available to alleviate the symptoms of PCOS.

Blood lipid levels mediating the effects of sex hormone-binding globulin on coronary heart disease: Mendelian randomization and mediation analysis

Observational studies indicate that serum sex hormone-binding globulin (SHBG) levels are inversely correlated with blood lipid levels and coronary heart disease (CHD) risk. Given that dyslipidemia is an established risk factor for CHD, we aim to employ Mendelian randomization (MR) in conjunction with mediation analysis to confirm the mediating role of blood lipid levels in the association between SHBG and CHD. First, we assessed the causality between serum SHBG levels and five cardiovascular diseases using univariable MR. The results revealed causality between SHBG levels and reduced risk of CHD, myocardial infarction, as well as hypertension. Specifically, the most significant reduction was observed in CHD risk, with an odds ratio of 0.73 (95% CI 0.63-0.86) for each one-standard-deviation increase in SHBG. The summary-level data of serum SHBG levels and CHD are derived from a sex-specific genome-wide association study (GWAS) conducted by UK Biobank (sample size = 368,929) and a large-scale GWAS meta-analysis (60,801 cases and 123,504 controls), respectively. Subsequently, we further investigated the mediating role of blood lipid level in the association between SHBG and CHD. Mediation analysis clarified the mediation proportions for four mediators: high cholesterol (48%), very low-density lipoprotein cholesterol (25.1%), low-density lipoprotein cholesterol (18.5%), and triglycerides (44.3%). Summary-level data for each mediator were sourced from the UK Biobank and publicly available GWAS. The above results confirm negative causality between serum SHBG levels and the risk of CHD, myocardial infarction, and hypertension, with the causal effect on reducing CHD risk largely mediated by the improvement of blood lipid profiles.

[Genetic Causation Analysis of Hyperandrogenemia Testing Indicators and Preeclampsia]

Objective

Some epidemiological studies have shown that pregnant women who develop preeclampsia (PE) have elevated levels of testosterone in their maternal plasma compared to women with normal blood pressure during pregnancy, revealing a potential association between hyperandrogenism in women and PE. To explore the causal relationship between hyperandrogenism and PE, this study selected total testosterone (TT), bioavailable testosterone (BIOT), and sex hormone binding globulin (SHBG) as exposure factors and PE and chronic hypertension with superimposed PE as disease outcomes. Two-sample Mendelian randomization (MR) analyses were used to genetically dissect the causal relationships between the three exposure factors (TT, BIOT, and SHBG) and the outcomes of PE and chronic hypertension with superimposed PE.

Methods

Two independent genome-wide association study (GWAS) databases were used for the two-sample MR analysis. In the GWAS data of female participants from the UK Biobank cohort, single nucleotide polymorphisms (SNPs) associated with TT, BIOT, and SHBG were analyzed, involving 230454, 188507, and 188908 samples, respectively. GWAS data on PE and chronic hypertension with superimposed PE from the Finnish database were used to calculate SNP, involving 3556 PE cases and 114735 controls, as well as 38 cases of chronic hypertension with superimposed PE and 114735 controls. To meet the assumptions of instrumental relevance and independence in MR analysis, SNPs associated with exposure were identified at the genome-wide level (P<5.0×10-8), and those in linkage disequilibrium interference were excluded based on clustering thresholds of R 2<0.001 and an allele distance greater than 10000 kb. Known confounding factors, including previous PE, chronic kidney disease, chronic hypertension, diabetes, systemic lupus erythematosus, or antiphospholipid syndrome, were also identified and the relevant SNPs were removed. Finally, we extracted the outcome data based on the exposure-related SNPs in the outcome GWAS, integrating exposure and outcome data, and removing palindromic sequences. Five genetic causal analysis methods, including inverse variance-weighted method (IVW), MR-Egger regression, weighted median method, simple mode method, and weighted mode method, were used to infer causal relationships. In the IVW, it was assumed that the selected SNPs satisfied the three assumptions and provided the most ideal estimate of the effect. IVW was consequently used as the primary analysis method in this study. Considering the potential heterogeneity among the instrumental variables, random-effects IVW was used for MR analysis. The results were interpreted using odds ratios (OR) and the corresponding 95% confidence interval (CI) to explain the impact of exposure factors on PE and chronic hypertension with superimposed PE. If the CI did not include 1 and had a P value less than 0.05, the difference was considered statistically significant. Sensitivity analysis was conducted to assess heterogeneity and pleiotropy. Heterogeneity was examined using Cochran's Q test, and pleiotropy was assessed using MR-Egger intercept analysis. Additionally, leave-one-out analysis was conducted to examine whether individual SNPs were driving the causal associations. To further validate the findings, MR analyses were performed using the same methods and outcome variables, but with different exposure factors, including waist-to-hip ratio adjusted for BMI (WHRadjBMI) and 25-hydroxyvitamin D levels, with MR results for WHRadjBMI and PE serving as the positive controls and MR results for 25-hydroxyvitamin D levels and PE as the negative controls.

Results

According to the criteria for selecting genetic instrumental variables, 186, 127, and 262 SNPs were identified as genetic instrumental variables significantly associated with testosterone indicators TT, BIOT, and SHBG. MR analysis did not find a causal relationship between the TT, BIOT, and SHBG levels and the risk of developing PE and chronic hypertension with superimposed PE. The IVW method predicted that genetically predicted TT (OR [95% CI]=1.018 [0.897-1.156], P=0.78), BIOT (OR [95% CI]=1.11 [0.874-1.408], P=0.392), and SHBG (OR [95% CI]=0.855 [0.659-1.109], P=0.239) were not associated with PE. Similarly, genetically predicted TT (OR [95% CI]=1.222 [0.548-2.722], P=0.624), BIOT (OR [95% CI]=1.066 [0.242-4.695], P=0.933), and SHBG (OR [95% CI]=0.529 [0.119-2.343], P=0.402) were not significantly associated with chronic hypertension with superimposed PE. Additionally, MR analysis using the MR-Egger method, weighted median method, simple mode method, and weighted mode method yielded consistent results, indicating no significant causal relationship between elevated testosterone levels and PE or chronic hypertension with superimposed PE. Heterogeneity was observed for SHBG in the analysis with PE (Cochran's Q test, P=0.01), and pleiotropy was detected for BIOT in the analysis with PE (MR-Egger intercept analysis, P=0.014), suggesting that the instrumental variables did not affect PE through BIOT. Other instrumental variables did not show significant heterogeneity or pleiotropy. Leave-one-out analysis confirmed that the results of the MR analysis were not driven by individual instrumental variables. Consistent with previous MR studies, the results of the control MR analyses using WHRadjBMI and 25-hydroxyvitamin D levels supported the accuracy of the MR analysis approach and the methods used in this study.

Conclusion

The MR analysis results suggest that current genetic evidence does not support a causal relationship between TT, BIOT, and SHBG levels and the development of PE and chronic hypertension with superimposed PE. This study suggests that elevated testosterone may be a risk factor for PE but not a direct cause.

A genome-wide association study identifies a locus associated with knee extension strength in older Japanese individuals

Sarcopenia is a common skeletal muscle disease in older people. Lower limb muscle strength is a good predictive value for sarcopenia; however, little is known about its genetic components. Here, we conducted a genome-wide association study (GWAS) for knee extension strength in a total of 3452 Japanese aged 60 years or older from two independent cohorts. We identified a significant locus, rs10749438 which is an intronic variant in TACC2 (transforming acidic coiled-coil-containing 2) (P = 4.2 × 10-8). TACC2, encoding a cytoskeleton-related protein, is highly expressed in skeletal muscle, and is reported as a target of myotonic dystrophy 1-associated splicing alterations. These suggest that changes in TACC2 expression are associated with variations in muscle strength in older people. The association was consistently observed in young and middle-aged subjects. Our findings would shed light on genetic components of lower limb muscle strength and indicate TACC2 as a potential therapeutic target for sarcopenia.

The pivotal role of the X-chromosome in the genetic architecture of the human brain

Genes on the X-chromosome are extensively expressed in the human brain. However, little is known for the X-chromosome's impact on the brain anatomy, microstructure, and functional network. We examined 1,045 complex brain imaging traits from 38,529 participants in the UK Biobank. We unveiled potential autosome-X-chromosome interactions, while proposing an atlas outlining dosage compensation (DC) for brain imaging traits. Through extensive association studies, we identified 72 genome-wide significant trait-locus pairs (including 29 new associations) that share genetic architectures with brain-related disorders, notably schizophrenia. Furthermore, we discovered unique sex-specific associations and assessed variations in genetic effects between sexes. Our research offers critical insights into the X-chromosome's role in the human brain, underscoring its contribution to the differences observed in brain structure and functionality between sexes.

The retrotransposon - derived capsid genes PNMA1 and PNMA4 maintain reproductive capacity

The human genome contains 24 gag -like capsid genes derived from deactivated retrotransposons conserved among eutherians. Although some of their encoded proteins retain the ability to form capsids and even transfer cargo, their fitness benefit has remained elusive. Here we show that the gag -like genes PNMA1 and PNMA4 support reproductive capacity. Six-week-old mice lacking either Pnma1 or Pnma4 are indistinguishable from wild-type littermates, but by six months the mutant mice become prematurely subfertile, with precipitous drops in sex hormone levels, gonadal atrophy, and abdominal obesity; overall they produce markedly fewer offspring than controls. Analysis of donated human ovaries shows that expression of both genes declines normally with aging, while several PNMA1 and PNMA4 variants identified in genome-wide association studies are causally associated with low testosterone, altered puberty onset, or obesity. These findings expand our understanding of factors that maintain human reproductive health and lend insight into the domestication of retrotransposon-derived genes.

Causal relationships between modifiable risk factors and polycystic ovary syndrome: a comprehensive Mendelian randomization study

Background

Polycystic Ovary Syndrome (PCOS) is a heritable condition with an as yet unclear etiology. Various factors, such as genetics, lifestyle, environment, inflammation, insulin resistance, hyperandrogenism, iron metabolism, and gut microbiota, have been proposed as potential contributors to PCOS. Nevertheless, a systematic assessment of modifiable risk factors and their causal effects on PCOS is lacking. This study aims to establish a comprehensive profile of modifiable risk factors for PCOS by utilizing a two-sample Mendelian Randomization (MR) framework.

Methods

After identifying over 400 modifiable risk factors, we employed a two-sample MR approach, including the Inverse Variance Weighted (IVW) method, Weighted Median method, and MR-Egger, to investigate their causal associations with PCOS. The reliability of our estimates underwent rigorous examination through sensitivity analyses, encompassing Cochran's Q test, MR-Egger intercept analysis, leave-one-out analysis, and funnel plots.

Results

We discovered that factors such as smoking per day, smoking initiation, body mass index, basal metabolic rate, waist-to-hip ratio, whole body fat mass, trunk fat mass, overall health rating, docosahexaenoic acid (DHA) (22:6n-3) in blood, monounsaturated fatty acids, other polyunsaturated fatty acids apart from 18:2 in blood, omega-3 fatty acids, ratio of bisallylic groups to double bonds, omega-9 and saturated fatty acids, total lipids in medium VLDL, phospholipids in medium VLDL, phospholipids in very large HDL, triglycerides in very large HDL, the genus Oscillibacter, the genus Alistipes, the genus Ruminiclostridium 9, the class Mollicutes, and the phylum Tenericutes, showed a significant effect on heightening genetic susceptibility of PCOS. In contrast, factors including fasting insulin interaction with body mass index, sex hormone-binding globulin, iron, ferritin, SDF1a, college or university degree, years of schooling, household income, the genus Enterorhabdus, the family Bifidobacteriaceae, the order Bifidobacteriales, the class Actinobacteria, and the phylum Actinobacteria were determined to reduce risk of PCOS.

Conclusion

This study innovatively employs the MR method to assess causal relationships between 400 modifiable risk factors and the susceptibility of PCOS risk. It supports causal links between factors like smoking, BMI, and various blood lipid levels and PCOS. These findings offer novel insights into potential strategies for the management and treatment of PCOS.

Impact of androgenic anabolic steroid use on cardiovascular and mental health in Danish recreational athletes: protocol for a nationwide cross-sectional cohort study as a part of the Fitness Doping in Denmark (FIDO-DK) study

INTRODUCTION

The use of androgenic anabolic steroids (AASs) among recreational athletes is steadily increasing. However, knowledge regarding the potentially harmful effects of AAS primarily originates from case reports and small observational studies. This large-scale study aims to investigate the impact of AAS use on vascular plaque formation, preclinical coronary disease, cardiac function, circulating cardiovascular risk markers, quality of life (QoL) and mental health in a broad population of illicit AAS users.

METHODS AND ANALYSES

A nationwide cross-sectional cohort study including a diverse population of men and women aged ≥18 years, with current or previous illicit AAS use for at least 3 months. Conducted at Odense University Hospital, Denmark, the study comprises two parts. In part A (the pilot study), 120 recreational athletes with an AAS history will be compared with a sex-matched and age-matched control population of 60 recreational athletes with no previous AAS use. Cardiovascular outcomes include examination of non-calcified coronary plaque volume and calcium score using coronary CT angiography, myocardial structure and function via echocardiography, and assessing carotid and femoral artery plaques using ultrasonography. Retinal microvascular status is evaluated through fundus photography. Cardiovascular risk markers are measured in blood. Mental health outcomes include health-related QoL, interpersonal difficulties, body image concerns, aggression dimensions, anxiety symptoms, depressive severity and cognitive function assessed through validated questionnaires. The findings of our comprehensive study will be used to compose a less intensive investigatory cohort study of cardiovascular and mental health (part B) involving a larger group of recreational athletes with a history of illicit AAS use.

ETHICS AND DISSEMINATION

The study received approval from the Regional Committee on Health Research Ethics for Southern Denmark (S-20210078) and the Danish Data Protection Agency (21/28259). All participants will provide signed informed consent. Research outcomes will be disseminated through peer-reviewed journals and scientific conferences.

TRIAL REGISTRATION NUMBER

NCT05178537.

The influence of trinucleotide repeats in the androgen receptor gene on androgen-related traits and diseases

CONTEXT

Trinucleotide repeats in the androgen receptor have been proposed to influence testosterone signaling in men, but the clinical relevance of these trinucleotide repeats remains controversial.

OBJECTIVE

To examine how androgen receptor trinucleotide repeat lengths affect androgen-related traits and disease risks and whether they influence the clinical importance of circulating testosterone levels.

METHODS

We quantified CAG and GGC repeat lengths in the androgen receptor (AR) gene of European-ancestry male participants in UK Biobank from whole-genome and whole-exome sequence data using ExpansionHunter, and tested associations with androgen-related traits and diseases. We also examined whether the associations between testosterone levels and these outcomes were affected by adjustment for the repeat lengths.

RESULTS

We successfully quantified the repeat lengths from whole-genome and/or whole-exome sequence data in 181,217 males. Both repeat lengths were shown to be positively associated with circulating total testosterone level and bone mineral density, whereas CAG repeat length was negatively associated with male-pattern baldness, but their effects were relatively small and were not associated with most of the other outcomes. Circulating total testosterone level was associated with various outcomes, but this relationship was not affected by adjustment for the repeat lengths.

CONCLUSION

In this large-scale study, we found that longer CAG and GGC repeats in the AR gene influence androgen resistance, elevate circulating testosterone level via a feedback loop and play a role in some androgen-targeted tissues. Generally, however, circulating testosterone level is a more important determinant of androgen action in males than repeat lengths.

Association of sex hormones with non-alcoholic fatty liver disease: An observational and Mendelian randomization study

BACKGROUND AND AIMS

Sex-specific associations of sex hormone-binding globulin (SHBG) and bioavailable testosterone (BAT) with NAFLD remain indeterminate. We aimed to explore observational and genetically determined relationships between each hormone and NAFLD.

METHODS

We included 187 395 men and 170 193 women from the UK Biobank. Linear and nonlinear Cox regression models and Mendelian randomization (MR) analysis were used to test the associations.

RESULTS

During 12.49 years of follow-up, 2209 male and 1886 female NAFLD cases were documented. Elevated SHBG levels were linearly associated with a lower risk of NAFLD in women (HR (95% CI), .71 (.63, .79)), but not in men (a "U" shape, pnon-linear < .001). Higher BAT levels were associated with a lower NAFLD risk in men (HR (95% CI), .81 (.71, .93)) but a higher risk in women (HR (95% CI): 1.25 (1.15, 1.36)). Genetically determined SHBG and BAT levels were linearly associated with NAFLD risk in women (OR (95% CI): .57 (.38, .87) and 2.21 (1.41, 3.26) respectively); in men, an "L-shaped" MR association between SHBG levels and NAFLD risk was found (pnon-linear = .016). The bidirectional MR analysis further revealed the effect of NAFLD on SHBG and BAT levels in both sexes.

CONCLUSIONS

Consistently, linear associations of lower SHBG and higher BAT levels with increased NAFLD risk were both conventionally and genetically found in women, while in men, SHBG acts in a nonlinear manner. In addition, NAFLD may affect SHBG and BAT levels.

Fathers and sons, mothers and daughters: Sex-specific genetic architecture for fetal testosterone in a wild mammal

Testosterone plays a critical role in mediating fitness-related traits in many species. Although it is highly responsive to environmental and social conditions, evidence from several species show a heritable component to its individual variation. Despite the known effects that in utero testosterone exposure have on adult fitness, the heritable component of individual testosterone variation in fetuses is mostly unexplored. Furthermore, testosterone has sex-differential effects on fetal development, i.e., a specific level may be beneficial for male fetuses but detrimental for females, producing sexual conflict. Such sexual conflict may be resolved by the evolution of a sex-specific genetic architecture of the trait. Here, we quantified fetal testosterone levels in a wild species, free-ranging nutrias (Myocastor coypus) using hair-testing and estimated testosterone heritability between parent and offspring from the same and opposite sex. We found that in utero accumulated hair testosterone levels were heritable between parents and offspring of the same sex. Moreover, there was a low additive genetic covariance between the sexes, and a low cross-sex genetic correlation, suggesting a potential for sex-specific trait evolution, expressed early on, in utero.

The effect of androgens on the risk of endometriosis sub-phenotypes and ovarian neoplasms: A Mendelian randomization study

Endometriosis is a complex gynecological pathology with a broad spectrum of symptoms, affecting around 10% of reproductive-aged women. Ovarian cancer (OC) is a heterogeneous disease for which we lack effective diagnostic and therapeutic strategies. The etiology and pathogenesis of both diseases remain ambiguous. Androgens in endometriosis could have a distinct role beyond serving as estrogen sources, whereas in the case of serous OC could be important in the formation of precursor lesions which ultimately lead to tumor formation. Here we performed two-sample Mendelian randomization (MR) analysis to examine the causal relationship between the androgen precursor - dehydroepiandrosterone sulphate (DHEAS), bioactive androgen - testosterone (T), androgen metabolite - androsterone sulphate, steroid hormone binding globulin (SHBG) and albumin and the risk of endometrioses of various sub-phenotypes and ovarian neoplasms across the benign-borderline-malignant spectrum. Stringent quality control procedures were followed to select eligible instrumental variables that were strongly associated with the selected exposures, sensitivity analyses were performed to assess the heterogeneities, horizontal pleiotropy, and stabilities of SNPs in endometriosis and ovarian neoplasms. We discovered an inverse association between genetically predicted levels of all androgens and risk of endometriosis, the same trend was most evident in the ovarian sub-phenotype. Total T levels were also inversely associated with peritoneal sub-phenotype of endometriosis. Likewise, T was causally associated with decreased risk of clear-cell OC, an endometriosis-associated OC subtype, and with malignant serous OC of both low- and high-grade, but with higher risk of their counterpart of low malignant potential. These findings support further investigation of androgen's action at a molecular level in ovary-associated endometriotic lesions, clear cell ovarian tumors and serous precursor lesions.

Association of genetically determined chronotype with circulating testosterone: a Mendelian randomization study

Low testosterone levels in men have been linked to decreased physical and mental function, as well as a reduced quality of life. Previous prospective observational studies have suggested an association between testosterone and sleep traits, but the causality of this relationship remains unclear. We aimed to explore the potential causal link between genetically determined sleep traits and testosterone levels in men using Mendelian randomization (MR) analysis from the UK Biobank dataset. Our exposures were genetic variants associated with sleep traits (chronotype and sleep duration), whereas our outcomes were traits of sex steroid hormones (total testosterone, TT; bioavailable testosterone, BAT; and sex hormone-binding globulin, SHBG). We employed inverse variance weighted (IVW) and weighted median (WM) methods to assess the causal associations. The IVW method offers a robust estimate of causality, whereas the WM method provides reliable results even when some genetic variants are invalid instruments. Our main analysis involving sex steroid hormones and chronotype identified 155 chronotype-related variants. The primary findings from the analysis, which used chronotype as the exposure and sex steroid hormones as the outcomes, showed that a genetically predicted chronotype score was significantly associated with an increased levels of TT (association coefficient β, 0.08; 95% confidence interval [CI], 0.02-0.14; P = 0.008) and BAT (β, 0.08; 95% CI, 0.02-0.14; P = 0.007), whereas there was no significant association with SHBG (β, 0.01; 95% CI, -0.02-0.03; P = 0.64). Meanwhile, MR analysis of sex steroid hormones and sleep duration was performed, and 69 variants associated with sleep duration were extracted. There were no significant association between sleep duration and sex steroid hormones (TT, P = 0.91; BAT, P = 0.82; and SHBG, P = 0.95). Our data support a causal association between chronotype and circulating testosterone levels in men. These findings underscore a potential causal relationship between chronotype and testosterone levels in men, suggesting that lifestyle adjustments are crucial for men's health. Recognizing factors that influence testosterone is essential. One limitation of this study is the use of one-sample MR, which can introduce potential bias due to non-independence of genetic associations for exposure and outcome. In conclusion, our findings indicate that a morning preference is correlated with circulating testosterone levels, emphasizing the potential impact of lifestyle habits on testosterone levels in men.

Effect of gut hormones on bone metabolism and their possible mechanisms in the treatment of osteoporosis

Bone is a highly dynamic organ that changes with the daily circadian rhythm. During the day, bone resorption is suppressed due to eating, while it increases at night. This circadian rhythm of the skeleton is regulated by gut hormones. Until now, gut hormones that have been found to affect skeletal homeostasis include glucagon-like peptide-1 (GLP-1), glucagon-like peptide-2 (GLP-2), glucose-dependent insulinotropic polypeptide (GIP), and peptide YY (PYY), which exerts its effects by binding to its cognate receptors (GLP-1R, GLP-2R, GIPR, and Y1R). Several studies have shown that GLP-1, GLP-2, and GIP all inhibit bone resorption, while GIP also promotes bone formation. Notably, PYY has a strong bone resorption-promoting effect. In addition, gut microbiota (GM) plays an important role in maintaining bone homeostasis. This review outlines the roles of GLP-1, GLP-2, GIP, and PYY in bone metabolism and discusses the roles of gut hormones and the GM in regulating bone homeostasis and their potential mechanisms.