Genomic analyses identify hundreds of variants associated with age at menarche and support a role for puberty timing in cancer risk

LIN 28B expression is downregulated in mature spermatozoa of oligozoospermic men and associates with genetic variants previously linked to pubertal onset

LIN28B is an RNA-binding protein that acts as a post-transcriptional regulator of genes involved in developmental timing and self-renewal through its interaction with let-7 miRNAs. Large-scale genomic studies have strongly implicated SNPs in LIN28B with male puberty timing. In addition, the occurrence of late puberty is linked to diminished semen quality in adult life. Therefore, we aimed to study the association of puberty-linked LIN28B genetic variants with semen parameters, reproductive hormones and the spermatozoa expression of the LIN28B/Let-7 axis in idiopathic oligozoospermic men. One hundred and eleven oligozoospermic (cases) and 258 men with normal sperm concentration (controls) were genotyped for five LIN28B SNPs (rs7759938, rs395962, rs314268, rs314277 and rs314280). The abundance of the LIN28B transcript, let-7a and let-7c miRNAs were measured by qRT-PCR in RNA isolated from purified sperm. Serum blood samples were analysed for reproductive hormones. Lower abundance of the LIN28B transcript and higher expression of let-7c were observed in cases (P < 0.001). Furthermore, rs395962_T was associated with a reduced abundance of the LIN28B transcript in cases (dominant: P = 0.032). On the other side, we observed a positive association of rs314277_A (Additive: P = 0.024), rs7759938_C (dominant: P = 0.025) and rs314280_A (dominant: P = 0.024) with total testosterone levels in cases. The decreased transcript abundance of LIN28B in sperm of idiopathic oligozoospermic men and its association with SNPs known to affect the onset of puberty and total testosterone levels suggests a role for LIN28B in the primary impairment of spermatogenesis through its expression in early germ cells or regulating the testicular biosynthesis of testosterone at a central level. Therefore, our results provide a potential mechanistic link between the regulation of pubertal timing and adult testicular function.

Maternal time interval between menarche and childbirth is associated with daughter's age at menarche

INTRODUCTION

Women's reproductive lifespan has increased over the past two decades. Simultaneously, female reproductive behavior has changed, with increasing age at first birth. Early menarche has been associated with adverse health outcomes, but research investigating the association between maternal age at childbirth and daughter's age at menarche is, so far, inconclusive. Whether the interval between menarche and childbirth or between childbirth and menopause among mothers is associated with age at menarche in daughters is not known.

MATERIAL AND METHODS

We conducted a cohort study with retrospectively collected data including mothers and daughters participating in the Norwegian Mother, Father and Child Cohort Study. Within this cohort, we identified two study populations. First, we included 14 576 mother-daughter pairs with complete information on maternal age at menarche and childbirth and the daughter's age at menarche. Second, we included 1350 mother-daughter pairs with complete information on maternal age at childbirth and natural menopause, and daughter's age at menarche. We calculated odds ratios (OR) with 95% confidence intervals (CIs) in a discrete survival analysis for daughters' age at menarche by time intervals from menarche to childbirth or from childbirth to menopause in mothers. We adjusted for relevant covariates.

RESULTS

We found 5% lower yearly odds (partially adjusted OR 0.95 (CI 0.90-0.99)) of reaching menarche among daughters born by mothers <16 years after menarche compared to the reference category born 16-20 years following menarche. After additionally adjusting for maternal birth year, the effect estimate was further reduced (fully adjusted OR 0.79 (CI 0.74-0.84)). Among daughters born by mothers >20 years after menarche, the likelihood of early menarche was higher (fully adjusted OR 1.19 (CI 1.13-1.27)) compared to the reference category. Regarding the childbirth-menopause interval, our findings did not reach statistical significance in either of our models.

CONCLUSIONS

Daughters born to mothers with a shorter time interval (<16 years) between menarche and childbirth have a lower likelihood of experiencing early menarche compared to the reference category (16-20 years), and daughters born to mothers with a longer time interval from menarche to childbirth (>20 years) have a higher likelihood of reaching early menarche.

Risk factors for precocious puberty: A systematic review and meta‑analysis

PURPOSE

Precocious puberty (PP) typically refers to the initiation of puberty prior to the age of eight in females and before the age of nine in males. The objective of this systematic review and meta-analysis is to pinpoint the risk factors linked to PP, thereby facilitating early diagnosis and timely intervention for individuals at high risk.

METHODS

A thorough search was carried out in the Cochrane Library, PubMed, and Embase databases up to November 10, 2024. The eligible studies comprised participants diagnosed with PP in the exposure group and participants without PP in the control group. The odds ratio (OR) and weighted mean difference (WMD) with 95 % confidence interval (CI) were computed using a random-effects model.

RESULTS

Out of 653 initially identified papers, 13 studies involving 15 cohorts were ultimately included. The mate-analysis findings indicated significant associations between several factors and the incidence of PP: BMI, maternal menarche age, and duration of breastfeeding. These three factors are significantly associated with the presence of pp: estrogen (E2) levels, follicle-stimulating hormone (FSH) levels, luteinizing hormone (LH) levels.

CONCLUSION

The occurrence of PP is strongly associated with several factors including BMI, maternal menarche age, and breastfeeding duration. The presence of PP is associated with three factors including E2, LH, FSH.

Brain-associated alterations of Hippo pathway transcription in early maturing Atlantic salmon

BACKGROUND

Pubertal timing is a key life history trait, shaped by ecological pressures to balance reproductive success and survival. Emerging evidence suggests a link between adiposity and early maturation, potentially through hormonal signaling pathways governing puberty timing. The timing of sexual maturation in Atlantic salmon has a strong genetic basis in addition to being linked with environmental shifts and lipid reserves. A gene encoding a co-factor of the Hippo pathway, vgll3, is a major determinant of maturation timing in salmon. The Hippo pathway is known for its evolutionary conserved molecular signal role in both sexual maturation and adipogenesis.

RESULTS

In this study, we tested the expression of Hippo pathway genes in the brain of immature and mature male Atlantic salmon carrying either the early or the late maturation genotype of vgll3. We found increased brain expression of a major Hippo pathway kinase (lats1b) in individuals with early maturation genotypes of vgll3 before maturation development of testes was evident. Moreover, we found components and regulating partners of the Hippo pathway showing differential expression in brain of individuals with early and late vgll3 genotypes prior to maturation. This may suggest a role for the Hippo pathway in central nervous system processes that regulate the preparation for maturation.

CONCLUSIONS

This study characterizes transcriptional changes in components of the Hippo pathway in the brain in relation to vgll3-mediated early maturation in Atlantic salmon, highlighting the potential involvement of this pathway in the central regulation of maturation prior to gonadal development.

Distribution of age at natural menopause, age at menarche, menstrual cycle length, height and BMI in BRCA1 and BRCA2 pathogenic variant carriers and non-carriers: results from EMBRACE

BACKGROUND

Carriers of germline pathogenic variants (PVs) in the BRCA1 and BRCA2 genes are at higher risk of developing breast and ovarian cancer than the general population. It is unclear if these PVs influence other breast or ovarian cancer risk factors, including age at menopause (ANM), age at menarche (AAM), menstrual cycle length, BMI or height. There is a biological rationale for associations between BRCA1 and BRCA2 PVs and reproductive traits, for example involving DNA damage and repair mechanisms. The evidence for or against such associations is limited.

METHODS

We used data on 3,046 BRCA1 and 3,264 BRCA2 PV carriers, and 2,857 non-carrier female relatives of PV carriers from the Epidemiological Study of Familial Breast Cancer (EMBRACE). Associations between ANM and PV carrier status was evaluated using linear regression models allowing for censoring. AAM, menstrual cycle length, BMI, and height in carriers and non-carriers were compared using linear and multinomial logistic regression. Analyses were adjusted for potential confounders, and weighted analyses carried out to account for non-random sampling with respect to cancer status.

RESULTS

No statistically significant difference in ANM between carriers and non-carriers was observed in analyses accounting for censoring. Linear regression effect sizes for ANM were -0.002 (95%CI: -0.401, 0.397) and -0.172 (95%CI: -0.531, 0.188), for BRCA1 and BRCA2 PV carriers respectively, compared with non-carrier women. The distributions of AAM, menstrual cycle length and BMI were similar between PV carriers and non-carriers, but BRCA1 PV carriers were slightly taller on average than non-carriers (0.5 cm difference, p = 0.003).

CONCLUSION

Information on the distribution of cancer risk factors in PV carriers is needed for incorporating these factors into multifactorial cancer risk prediction algorithms. Contrary to previous reports, we found no evidence that BRCA1 or BRCA2 PV are associated with hormonal or anthropometric factors, except for a weak association with height. We highlight methodological considerations and data limitations inherent in studies aiming to address this question.

Identification of loci associated with women's reproductive traits and exploration of a shared genetic basis with obesity

BACKGROUND

The timing of menarche and menopause significantly affects women's health, with influences on cancer, cardiovascular disease, obesity, type 2 diabetes, and psychosocial problems. In addition, observational studies have reported that ages at menarche (AAM) and natural menopause (ANM) are correlated with obesity. To understand the genetic bases of these reproductive traits, we conducted a genome-wide association study (GWAS) of AAM and ANM in the Korean population. We also investigated the genetic correlation and causal relationship to explore the shared genetic architecture between reproductive traits and obesity in women.

RESULTS

Our GWA analyses of 45,608 and 21,599 adult women identified two and six genome-wide significant associations (P-value < 5 × 10- 8) for AAM and ANM, respectively. Although most of the loci that we detected have been reported in previous studies, we have newly linked the JHY locus containing the SNP rs11605693 to AAM. Leveraging the GWAS results, we tested the shared genetic basis underlying AAM and ANM, which appear to be closely related to female hormone activity. Linkage disequilibrium score regression (LDSC) analysis did not identify a significant genetic correlation between the two traits. Our LDSC analyses indicated that AAM was inversely correlated with two obesity traits, body mass index (BMI) and waist circumference (WC). However, Mendelian randomization (MR) analyses did not provide evidence of a causal relationship between AAM and obesity traits.

CONCLUSIONS

Overall, our study provides insights into the genetic architecture of women's reproductive traits and the shared genetic basis between AAM and obesity. Our MR analyses suggest that the genetic correlation between AAM and obesity traits results from the direct effects of genetic variants on both traits rather than a causal relationship between them.

Serum DLK1 During Minipuberty and Pubertal Transition in Healthy Girls and in Girls With Precocious Puberty

CONTEXT

Delta-like non-canonical notch ligand 1 (DLK1) is negatively associated with bodyweight. DLK1 pathogenic variants cause central precocious puberty (CPP) and obesity, suggesting that DLK1 links the well-established association between higher body mass index and earlier pubertal onset. However, little is known about the trajectories of circulating DKL1 in healthy girls as well as in girls with precocious puberty.

OBJECTIVE

To evaluate longitudinal changes in circulating DLK1 concentrations in (1) full-term, singleton healthy infant girls, (2) healthy girls during pubertal transition, and (3) girls with CPP during treatment with gonadotropin-releasing hormone agonist (GnRHa).

METHODS

Three longitudinal studies of (1) healthy infant girls (n = 85), (2) healthy peripubertal girls (n = 15), and (3) girls with CPP before and after GnRHa treatment (n = 15). Body fat percentage calculated using the Slaughter equation, and serum concentrations of DLK1 using enzyme-linked immunosorbent assay.

RESULTS

Serum concentration of DLK1 in healthy infant girls declined significantly through the first year of life (17.6 to 9.9 ng/mL, P = .020). DLK1 was inversely correlated with birth weight and BF%: r = -0.220, P = .044, and r = -0.503, P < .001, respectively. DLK1 declined from 1 year prior to pubertal onset to time of first examination after pubertal onset (10.4  to 9.2 ng/mL, P = .004), as well as to time at the last pubertal evaluation (10.4 to 9.8 ng/mL, P = .006). DLK1 levels were not affected by GnRHa treatment.

CONCLUSION

Circulating DLK1 levels declined steeply during infancy and were less pronounced through pubertal development. Due to considerable interindividual variation, DLK1 is not useful as a diagnostic marker of pubertal onset. Importantly, DLK1 was negatively associated with birth weight and body fat percentage.

Pubertal timing as a predictor of epigenetic aging and mortality risk in young adulthood

Early pubertal timing is associated with adverse health in adulthood. These effects may be mediated by DNA methylation changes associated with accelerated cellular aging and mortality risk, but few studies tested associations between pubertal timing and epigenetic markers in adulthood. Additionally, pubertal timing effects often vary by sex and are understudied in diverse youth. Thus, this longitudinal study examined links between pubertal timing and later epigenetic aging and mortality risk together with sex differences in predominantly Black youth. Participants included 350 individuals (58% female, 42% male; 80% Black, 19% non-Hispanic White). Perceived pubertal timing relative to peers and self-reported phenotypic pubertal timing based on age-adjusted Tanner scores were assessed during early adolescence (Mage = 13) whereas epigenetic aging (GrimAge, DunedinPace of Aging Calculated from the Epigenome, and PhenoAge) and mortality risk were measured during young adulthood (Mage = 27). After adjusting for covariates (smoking, body mass index, family income, early-life stress, race/ethnicity, sex, parenthood), early pubertal timing (both perceived and phenotypic) predicted higher epigenetic mortality risk, and early phenotypic pubertal timing predicted accelerated DunedinPace of Aging Calculated from the Epigenome. Both perceived and phenotypic early pubertal timing were correlated with accelerated GrimAge. Off-time phenotypic pubertal timing (i.e., early and late) was associated with accelerated PhenoAge in males only whereas perceived off-time pubertal timing was unexpectedly linked with lower PhenoAge acceleration. These findings extend prior research by linking two dimensions of early pubertal timing with epigenetic mortality risk and accelerated aging in racially diverse young adults and showing nonlinear effects on PhenoAge acceleration that differ across pubertal timing measures and show some sex differences. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Comprehensive systematic review and meta-analysis of risk factors for childhood obesity in China and future intervention strategies

Background

Childhood obesity is a critical public health concern in China. This study identified the key determinants of childhood obesity in China and provided recommendations for future intervention strategies.

Methods

We conducted a comprehensive systematic review and meta-analysis to identify multiple-level determinants of childhood obesity in China and calculated the population-attributable risk percentage (PAR%) for each modifiable determinant. We also conducted expert consultations using the Socio-ecological Model to gain insights into the causes of obesity. Additionally, we reviewed current Chinese policies on childhood obesity intervention and compared them with the priorities identified in the meta-analysis and expert consultation to pinpoint policy gaps.

Findings

Our meta-analysis, incorporating 419 studies, identified 33 risk factors for childhood obesity. At the individual-level, we identified 11 key contributors including early-life risk factors such as maternal pre-pregnancy overweight/obesity (PAR%: 16.7%), breastfeeding duration of less than six months (14.1%), cesarean section delivery (11.1%), excessive gestational weight gain (10.5%), high birth weight (4.2%), and gestational diabetes mellitus (3.6%), and 13 behavioral factors during childhood such as sugar sweetened beverage consumption (16.4%), insufficient sleep (15.0%), rapid eating speed (14.7%), less than 2 h of physical activity per day (6.3%), and over 2 h of daily screen time (5.6%). We also identified six prominent family-level factors such as maternal overweight/obesity (24.3%) and paternal overweight/obesity (23.5%). Expert consultation highlighted genetic factors, and prioritized actionable risk factors, particularly dietary, expanding on the meta-analysis findings. Finally, policy review revealed that existing Chinese policies inadequately addressed these determinants, especially at the macro and structural levels.

Interpretation

This study highlights the importance of targeting high-risk populations and addressing detrimental behavioral factors, especially on early-life influences. However, real-world impacts require a comprehensive approach that goes beyond individual factors. More future effective intervention efforts are needed.

Funding

This study was funded by the National Natural Science Foundation of China (NSFC 82073567; NSFC 82273641) and the National Science and Technology Innovation 2030, Noncommunicable Chronic Diseases-National Science and Technology Major Project (Grant No. 2023ZD0508500, 2023ZD0508504).

The hippo pathway: a molecular bridge between environmental cues and pace of life

The pace of life (POL) is shaped by a complex interplay between genetic and environmental factors, influencing growth, maturation, and lifespan across species. The Hippo signaling pathway, a key regulator of organ size and cellular homeostasis, has emerged as a central integrator of environmental cues that modulate POL traits. In this review, we explore how the Hippo pathway links environmental factors-such as temperature fluctuations and dietary energy availability-to molecular mechanisms governing metabolic balance, hormonal signaling, and reproductive timing. Specifically, we highlight the regulatory interactions between the Hippo pathway and metabolic sensors (AMPK, mTOR, SIRT1 and DLK1-Notch), as well as hormonal signals (IGF-1, kisspeptin, leptin, cortisol, thyroid and sex steroids), which together orchestrate key life-history traits, including growth rates, lifespan and sexual maturation, with a particular emphasis on their role in reproductive timing. Furthermore, we consider its role as a potential coordinator of POL-related molecular processes, such as telomere dynamics and epigenetic mechanisms, within a broader regulatory network. By integrating insights from molecular biology and eco-evolutionary perspectives, we propose future directions to dissect the Hippo pathway's role in POL regulation across taxa. Understanding these interactions will provide new perspectives on how organisms adaptively adjust life-history strategies in response to environmental variability.

Assessing the causal association between age at menarche and genetic susceptibility to future gastroesophageal reflux disease risks: A two-sample Mendelian randomization study

OBJECTIVE

Evidence indicates that menarche onset is associated with various health outcomes. Gastroesophageal reflux disease (GERD) is a prevalent condition, which may be influenced by the age at menarche (AAM). The study aims to investigate the potential causal relationship between the AAM and GERD.

METHODS

We conducted a two-sample Mendelian randomization (MR) analysis utilizing single nucleotide polymorphisms (SNPs) derived from genome-wide association studies summary statistics for AAM and GERD as instrumental variables. Various MR methods were applied to estimate causal effects, supplemented by sensitivity analyses to assess the robustness of our findings.

RESULTS

Overall, 69 SNPs associated with the AAM were used after rigorous selection to ensure absence of linkage disequilibrium or association with confounding factors. The inverse variance-weighted (IVW) method indicated a significant inverse association between genetically predicted AAM and GERD (odds ratio, 0.89; 95 % confidence interval, 0.85-0.94). These findings were consistent across weighted median and weighted mode analyses. The MR-Egger regression analysis suggested no significant directional pleiotropy. Heterogeneity was detected among instrumental variables; however, the leave-one-out sensitivity analysis confirmed the association stability.

CONCLUSION

We provided robust evidence supporting an inverse causal relationship between the AAM and GERD risk.

Effect of maternal previous pregnancy on children's pubertal development: an 8-year pubertal cohort

STUDY QUESTION

Does the maternal pregnancy history affect the course of their offspring's pubertal development?

SUMMARY ANSWER

Maternal pregnancy history, particularly adverse outcomes, significantly influences the timing of menarche and the tempo of breast development in girls.

WHAT IS KNOWN ALREADY

Preliminary evidence indicates that parity may affect the onset of puberty, mainly as reflected by changes in the timing of pubic and axillary hair development.

STUDY DESIGN, SIZE, DURATION

This 8-year cohort, conducted semi-annually, was recruited from four primary schools. The average follow-up duration was 6.09 years (range: 2-8 years).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study cohort comprised 1390 children, including 710 girls and 680 boys, with age ranges of 6.58-19.26 years and 5.81-19.28 years, respectively, over an 8-year follow-up period. The primary exposure was whether the mother has a history of pregnancy prior to the birth of the child, including childbearing, miscarriage, and other adverse pregnancy outcomes. Pubertal milestones as assessed by a professional, including breast and genital development, were modeled using logistic regression, and the age of menarche was documented for girls. Associations between maternal pregnancy history and pubertal progression in both genders were analyzed using generalized linear regression models.

MAIN RESULTS AND THE ROLE OF CHANCE

Girls from non-first pregnancies experienced a delayed age at menarche by 0.22 years (95% CI: 0.05, 0.38) and a more rapid tempo of breast development (0.06; 95% CI: 0.01, 0.11) compared to those from first pregnancies, particularly among girls with a history of maternal adverse pregnancy outcomes. The effect of maternal pregnancy history on pubertal development was less pronounced in boys than in girls.

LIMITATIONS, REASONS FOR CAUTION

The sample was relatively small, and the cohort also lacks sufficient data due to missing data points and some study participants still maturing. While model fitting aids in describing incomplete pubertal development, the logistic growth mixed-effects model's assumptions about growth curves may not fully reflect reality.

WIDER IMPLICATIONS OF THE FINDINGS

Maternal pregnancy history, particularly adverse outcomes, can markedly influence pubertal progression in girls. Previous studies have shown that the timing and tempo of pubertal development impact adolescent psychological and behavioral health, and have implications for reproductive health and diseases in adulthood. Optimal pregnancy planning by mothers is essential for enhancing the well-being of both mother and offspring.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by Chongqing Natural Science Foundation project (CSTB2023NSCQ-MSX0133), National Natural Science Foundation of China (81973067), National Youth Science Fund Project (81502825), and Program for Youth Innovation in Future Medicine, Chongqing Medical University (W0054). This study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of Chongqing Medical University (Reference Number: 2023003). Informed consent was obtained from all participants and their guardians involved in the study. The authors declared that they have no conflicts of interest to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Manganese-induced Precocious Puberty Alters Mammary Epithelial Cell Proliferation in Female Rats

Precocious puberty (PP) is an established breast cancer risk factor. In the normal mammary gland, hormone receptor-positive (HR+) cells rarely proliferate. In breast cancer, proliferating epithelial cells are often HR+. It is not known if PP can modify this population of proliferating HR+ cells. Previously, we established a manganese-induced precocious puberty (MnPP) model to study the effects of PP on mammary gland development in female rats. Here, we characterized the distribution of HR+ proliferating mammary epithelial cells in prepubertal and adult rodents, in association with precocious puberty. Female rats were exposed daily to 10 mg/kg manganese chloride or saline (control) from postnatal day (PND) 12 to PND 30. Mammary glands were collected on PNDs 30 and 120, processed for western blot analysis and double immunofluorescence staining for proliferating cell nuclear antigen and progesterone receptor or estrogen receptor. MnPP increased the percentage of HR+ mammary epithelial cells coexpressing proliferating cell nuclear antigen relative to normally developed controls at PND 30. This correlated with increased expression of estrogen receptor-regulated proteins in MnPP mammary glands relative to controls at PND 30, including FOXA1, AREG, and c-Myc. Conversely, at PND 120 relative to PND 30, proliferating HR+ cells remained chronically elevated in MnPP mammary glands at PND 120, which coincided with decreased expression of cell-cycle regulator, p27, and increased expression of progesterone receptor-regulated markers, EREG and sp1. Collectively, these results suggest early puberty alters steroidal regulation of classic proliferative mechanisms in the prepubertal gland with increased prevalence of high-risk proliferating HR+ cells.

Association of DLK1 SNPs with body mass index and plasma lipid levels in children

BACKGROUND

The DLK1 human gene encodes for the transmembrane EGF-like repeat-containing protein DLK1, which acts as a modulator of adipogenesis. A role for DLK1 in energy metabolism and lipid homeostasis has been suggested and DLK1 gene variants have been related to pubertal development.

OBJECTIVE

The aim of this study was to uncover DLK1 SNPs in a cohort of children and analyze their relationship with anthropometric and biochemical variables.

METHODS

Our population-based sample comprises 1237 healthy 6-to-8-year-old Caucasian children. The presence of five DLK1 SNPs (rs1802710, rs876374, rs7155375, rs57098752, and rs7149242) was analyzed by Real-Time PCR, using predesigned TaqMan™ Genotyping Assays.

RESULTS

We observed that the SNPs rs1802710 and rs876374 were associated with BMI, and the prevalence of these two SNPs was different in normal-weight children compared to children with obesity. Related to biochemical variables, we found a significant association of the SNPs rs1802710, rs876374, and rs57098752 and their combination with Apo-B plasma concentrations after adjusting by BMI and sex. The SNPs rs1802710 and rs57098752 were also significantly associated with plasma levels of LDL-C and HDL-C, respectively.

CONCLUSION

Our study reveals that DLK1 gene variants may influence both body weight and lipid homeostasis, affecting particularly to the Apo-B biology, in children.

IMPACT

DLK1 polymorphisms are associated with BMI and with lipid levels, independently of BMI, early in life. Our data add to the existing literature the evidence that DLK1 gene variants impact on lipid metabolism. The confirmation at the population level that DLK1 genetic variants are associated with anthropometric and lipid variables sustains the role of DLK1 in obesity and related disorders and should lead to further studies aimed at clarifying this effect.

Reassessing the association between age at menarche and cardiovascular disease: observational and Mendelian randomization analyses

AIMS

Observational studies have shown a U-shaped association between age at menarche (AAM) and cardiovascular disease (CVD). We assessed non-linearity of the observational association and the potential causal relationship between AAM and CVD using data from the European Prospective Investigation into Cancer and Nutrition-Cardiovascular Disease (EPIC-CVD) study and the UK Biobank.

METHODS AND RESULTS

We included women without pre-existing myocardial infarction (MI) or stroke at baseline. We estimated hazard ratios for incident MI, ischaemic and haemorrhagic stroke later in life using Cox regression in observational analyses and conducted non-linear Mendelian randomization (MR) based on fractional polynomials and linear MR based on inverse-variance weighted regression. We analysed 283 210 women with a median AAM of 13 (IQR 12-14) years in both EPIC-CVD and the UK Biobank, of which 8468 experienced a MI, 5501 an ischaemic and 1887 a haemorrhagic stroke. The association between AAM and MI and ischaemic stroke was U-shaped with higher risks in women aged ≤12 and ≥16 compared with those aged 13 years at menarche. Our MR analyses found no evidence for non-linearity between genetically proxied AAM and any CVD endpoint later in life, but each year higher genetically proxied AAM was related to a lower risk of MI (hazard ratio 0.92 [95% CI 0.86-0.99]), but not to ischaemic and haemorrhagic stroke.

CONCLUSION

This study supported non-linear observational associations between AAM and MI and ischaemic stroke. MR analyses suggested a causal relationship between higher AAM and risk of MI without an indication for non-linearity. There was no support for a potential causal link with ischaemic and haemorrhagic stroke.

Shared Pathophysiological Mechanisms and Genetic Factors in Early Menarche and Polycystic Ovary Syndrome

Early age at menarche (early AAM) and polycystic ovary syndrome (PCOS) are reproductive and metabolic disorders with overlapping pathophysiological and genetic features. Epidemiological studies suggest a link between these two conditions, both of which are characterized by dysregulation of the neuroendocrine pathways that control pulsatile gonadotropin-releasing hormone secretion, thus affecting gonadotropin release, particularly luteinizing hormone secretion. A common pathophysiology involving positive energy balance and abnormal metabolic status is evident in both disorders. Genetic and epigenetic factors influence the onset of puberty and reproductive outcomes. Genome-wide association studies have identified common genetic variants associated with AAM and PCOS, particularly in genes related to the neuroendocrine axis (e.g., FSHB) and obesity (e.g., FTO). In addition, high-throughput sequencing has revealed rare loss-of-function variants in the DLK1 gene in women with central precocious puberty (CPP), early menarche, and PCOS, who experienced adverse metabolic outcomes in adulthood. This review explores the shared pathophysiological mechanisms between CPP/early AAM and PCOS, examines potential genetic and epigenetic factors that may link these neuroendocrine reproductive conditions, and offers insights into future research and treatment strategies. Understanding these connections may provide new targets for therapeutic interventions and improve outcomes for individuals with these reproductive disorders.

Genetic determinants of age at menarche: does the LIN28B gene play a role? A narrative review

Menarche, the first menstrual period marking the onset of female reproduction, is a milestone of female puberty. The timing of menarche determines the timing of later phases of pubertal maturation in girls and has major implications for health later in life, including behavioral and psychosocial disorders during adolescence and fertility problems and increased risk for certain diseases in adulthood. Over the last few decades, a continuous decline in age at menarche has been noted, with environmental factors contributing to this change in the timing of menarche. However, a genetic component of age at menarche and pubertal onset has been strongly suggested by studies in families and twins wherein up to approximately 80% of the variance in puberty onset can be explained by heritability. Gene association studies have revealed several genetic loci involved in age at menarche, among which LIN28B has emerged as a key regulator of female growth and puberty. LIN28B, a human homolog of Lin28 of C. elegans, is a known RNA-binding protein that regulates let-7 microRNA biogenesis. Genome-wide association studies have identified the association of polymorphisms in the LIN28B gene with age at menarche in several population cohorts worldwide. In this paper, we review the genetic factors contributing to age of menarche, with particular focus on the identified polymorphisms in LIN28B gene.

Risk Stratification for Endometrial Cancer Reveals Independent Contributions of Polygenic Risk and Body Mass Index

Background

Obesity is a major risk factor for endometrial cancer, but it is unknown whether it impacts the association between genetic risk and endometrial cancer. We incorporated polygenic risk score and epidemiological risk factors in the prediction of and investigated associations of BMI and polygenic risk score with endometrial cancer risk.

Methods

We generated polygenic risk score for endometrial cancer in 129,829 unrelated female participants of European ancestry (including 956 incident cases with endometrial cancer) in the UK Biobank and predicted endometrial cancer using endometrial cancer polygenic risk score and established epidemiological risk factors, including BMI. We evaluated the performance of endometrial cancer prediction models by odds ratios and area under the receiver operating characteristic curves (AUCs) to using logistic regression. Individual and joint associations of BMI and polygenic risk score with endometrial cancer were assessed using Cox proportional hazards models.

Results

An integrated model incorporating both polygenic risk score and epidemiological risk factors achieved a modest, but statistically significant, improvement in predicting endometrial cancer status compared with the model that included epidemiologic risk factors alone (AUC = 0.74 versus 0.73; P = 3.98 × 10 -5 ). Obese participants (BMI ≥ 30 kg/m 2 ) in the top polygenic risk tertile had the highest endometrial cancer risk. We observed independent effects of genetic risk and BMI on endometrial cancer risk.

Conclusion

Integrating polygenic risk score with epidemiological risk factors may offer insights into population stratification for endometrial cancer susceptibility. Higher endometrial cancer polygenic risk is associated with endometrial cancer, irrespective of BMI.

Insights into drug adverse reactions prediction through Mendelian randomization: a review

Adverse drug reactions pose a significant threat to patient safety and public health and often become apparent only after widespread clinical use. Mendelian randomization (MR) analysis is a valuable tool that can be used to infer causality by using genetic variants as instrumental variables, which can predict the occurrence of adverse drug reactions before they occur. Compared with traditional observational studies, MR Analysis can reduce the potential bias of confounding factors. This article reviews the principles of MR Analysis and its application in the prediction of adverse drug reactions, the challenges and future directions, and summarizes how to harness the power of this innovative epidemiological method to put us at the forefront of improving drug safety assessment and personalized medicine.

Mendelian randomization analysis of female reproductive factors on osteoarthritis

Epidemiology shows women have a higher incidence of osteoarthritis (OA) than men. However, there is not enough evidence to suggest a direct correlation between female reproductive factors and OA. Therefore, this study will employ Mendelian randomization (MR) analysis to investigate whether there is a causal relationship between the 2. This study used a 2-sample MR analysis with single nucleotide polymorphisms significantly associated with female reproductive factors as instrumental variables (IV). We used inverse variance weighted (IVW), MR-Egger regression, weighted median method to infer a causal relationship between female reproductive factors and OA, Cochran Q heterogeneity test by IVW and MR-Egger method, MR PRESSO method and IVW-radial method to detect outliers, MR_pleiotropy_test function and MR PRESSO method for multivariate validity test, and calculation of F-value was used to assess the presence of weak IVs. Finally, the stability of the findings was assessed using the leave-one-out method. Our research shows that there is no reliable causal relationship between an increase in Age at menarche (years) (AAM) and Age at menopause (years) (AM) and OA, that an increase in Age first had sexual intercourse (years) (AFS) is associated with a decreased risk of knee OA and/or hip OA and hand OA, that an increase in Age at first live birth (years) (AFB) is associated with a decreased risk of knee OA and/or hip OA and knee OA, and that an increase in Number of live births (NOB) is associated with an increased risk of knee OA and/or hip OA. This study provides genetic support for an increase in AFS as a reduced knee OA and/or hip OA and hand OA risk factor, an increase in AFB as a reduced knee OA and/or hip OA and knee OA risk factor, and an increase in NOB as an increased knee OA and/or hip OA risk factor. Further studies are needed to elucidate the potential mechanisms underlying the causal associations between AFS, AFB, and NOB and site-specific OA.

Cross-trait multivariate GWAS confirms health implications of pubertal timing

Pubertal timing is highly variable and is associated with long-term health outcomes. Phenotypes associated with pubertal timing include age at menarche, age at voice break, age at first facial hair and growth spurt, and pubertal timing seems to have a shared genetic architecture between the sexes. However, puberty phenotypes have primarily been assessed separately, failing to account for shared genetics, which limits the reliability of the purported health implications. Here, we model the common genetic architecture for puberty timing using a multivariate GWAS, with an effective population of 514,750 European participants. We find 266 independent variants in 197 loci, including 18 novel variants. Transcriptomic, proteome imputation and fine-mapping analyses reveal genes causal for pubertal timing, including KDM4C, LEPR, CCNC, ACP1, and PCSK1. Linkage disequilibrium score regression and Mendelian randomisation analysis establish causal associations between earlier puberty and both accelerated ageing and the risk of developing cardiovascular disease and osteoporosis. We find that alanine aminotransferase, glycated haemoglobin, high-density lipoprotein cholesterol and Parabacteroides levels are mediators of these relationships, and establish that controlling oily fish and retinol intake may be beneficial for promoting healthy pubertal development.

Lin28b-let-7 Modulates mRNA Expression of GnRH1 Through Multiple Signaling Pathways Related to Glycolysis in GT1-7 Cells

Lin28b and let-7 miRNA regulate mammalian pubertal initiation and Gonadotropin-releasing hormone (GnRH) production. However, it remains unclear which signaling pathways Lin28b regulates to modulate GnRH production. In this study, the mRNA expression levels of Lin28b and let-7 in the pubertal and juvenile goat hypothalamus and pituitary gland were detected, and Lin28b expression in the pubertal hypothalamus decreased significantly compared with that in juvenile tissues. It was predicted that Lin28b might inhibit GnRH1 expression, which was verified in the GnRH-producing cell model GT1-7 cells. Lin28b inhibited GnRH1 expression and promoted Kiss1/Gpr54 signaling. The pyruvate content and the expression of Hif1a and Hk2, which were related to glycolysis, were also promoted by Lin28b overexpression. Additionally, 77 differentially expressed miRNAs (DEMIs) in Lin28b-overexpressed GT1-7 cells were identified. Bioinformatics analysis and mRNA expression of the target genes of DEMIs revealed that the MAPK and PI3K-AKT-mTOR signaling pathways were key pathways that involved the regulatory effect of Lin28b on GnRH. In GT1-7 cells, GnRH1 expression was suppressed by blocking mTOR signaling with rapamycin, which was rescued by Lin28b overexpression. These results indicate that Lin28b-let-7 regulates GnRH1 expression through several pathways, including the Kiss1/Gpr54, MAPK, and mTOR signaling pathways, which are all related to glucose metabolism and provide new insights into the molecular mechanism of the regulatory role of Lin28b on GnRH production.

Genetics and Epigenetics of Human Pubertal Timing: The Contribution of Genes Associated With Central Precocious Puberty

Human puberty is a dynamic biological process determined by the increase in the pulsatile secretion of GnRH triggered by distinct factors not fully understood. Current knowledge reveals fine tuning between an increase in stimulatory factors and a decrease in inhibitory factors, where genetic and epigenetic factors have been indicated as key players in the regulation of puberty onset by distinct lines of evidence. Central precocious puberty (CPP) results from the premature reactivation of pulsatile secretion of GnRH. In the past decade, the identification of genetic causes of CPP has largely expanded, revealing hypothalamic regulatory factors of pubertal timing. Among them, 3 genes associated with CPP are linked to mechanisms involving DNA methylation, reinforcing the strong role of epigenetics underlying this disorder. Loss-of-function mutations in Makorin Ring-Finger Protein 3 (MKRN3) and Delta-Like Non-Canonical Notch Ligand 1 (DLK1), 2 autosomal maternally imprinted genes, have been described as relevant monogenic causes of CPP with the phenotype exclusively associated with paternal transmission. MKRN3 has proven to be a key component of the hypothalamic inhibitory input on GnRH neurons through different mechanisms. Additionally, rare heterozygous variants in the Methyl-CpG-Binding Protein 2 (MECP2), an X-linked gene that is a key factor of DNA methylation machinery, were identified in girls with sporadic CPP with or without neurodevelopmental disorders. In this mini-review, we focus on how the identification of genetic causes of CPP has revealed epigenetic regulators of human pubertal timing, summarizing the latest knowledge on the associations of puberty with MKRN3, DLK1, and MECP2.

Lifelong impacts of puberty timing on human plasma metabolic profiles: A metabolome-wide Mendelian randomization study

AIM

The aim was to investigate the causal relationship between puberty timing and plasma metabolites, accounting for birth weight, childhood and adulthood adiposity.

MATERIALS AND METHODS

The meta-analysis of genome-wide association studies (GWAS) for puberty timing was extracted from the ReproGen Consortium, involving 329 345 women of European ancestry. Summary data for 174 plasma metabolites were retrieved from a recently conducted cross-platform GWAS that involved a meta-analysis of three cohort studies (i.e. the Fenland, European Prospective Investigation into Cancer-Norfolk and INTERVAL studies) and three publicly available studies and included up to 86 507 participants. We conducted a two-sample Mendelian randomization (MR) analysis to infer the causal relationship of puberty timing on 174 plasma metabolites, complemented by a two-step and multivariable Mendelian randomization (MVMR) analysis to assess direct and indirect effects. Additionally, summary-level data from the UK Biobank were used for our replication analysis.

RESULTS

The results of the two-sample MR provide moderate evidence supporting a causal relationship between puberty timing and 23 of 174 plasma metabolites (i.e. 7 acylcarnitines, 8 amino acids, 2 biogenic amines and 6 lysophosphatidylcholines). Even after single-nucleotide polymorphisms associated with birth weight and childhood adiposity were excluded, causal effects persisted for 16 metabolites (i.e. 8 acylcarnitines, 4 amino acids, 2 biogenic amines and 2 lysophosphatidylcholines). The two-step MR analysis provided evidence that the relationship between puberty timing and plasma metabolites was mediated by adulthood adiposity. Additionally, moderate evidence emerged for an independent causal effect of puberty timing on 10 metabolites through an MVMR analysis (i.e. 5 acylcarnitines, 2 amino acids, 1 biogenic amine, 1 lysophosphatidylcholine and 1 phosphatidylcholine). Furthermore, the replication analysis suggested the robustness of our results.

CONCLUSIONS

In summary, our study provides compelling evidence that puberty timing has a causal influence on certain plasma metabolites, although this influence is largely mediated by adulthood adiposity.

The human and non-human primate developmental GTEx projects

Many human diseases are the result of early developmental defects. As most paediatric diseases and disorders are rare, children are critically underrepresented in research. Functional genomics studies primarily rely on adult tissues and lack critical cell states in specific developmental windows. In parallel, little is known about the conservation of developmental programmes across non-human primate (NHP) species, with implications for human evolution. Here we introduce the developmental Genotype-Tissue Expression (dGTEx) projects, which span humans and NHPs and aim to integrate gene expression, regulation and genetics data across development and species. The dGTEx cohort will consist of 74 tissue sites across 120 human donors from birth to adulthood, and developmentally matched NHP age groups, with additional prenatal and adult animals, with 126 rhesus macaques (Macaca mulatta) and 72 common marmosets (Callithrix jacchus). The data will comprise whole-genome sequencing, extensive bulk, single-cell and spatial gene expression profiles, and chromatin accessibility data across tissues and development. Through community engagement and donor diversity, the human dGTEx study seeks to address disparities in genomic research. Thus, dGTEx will provide a reference human and NHP dataset and tissue bank, enabling research into developmental changes in expression and gene regulation, childhood disorders and the effect of genetic variation on development.

Contributions of Common Genetic Variants to Constitutional Delay of Puberty and Idiopathic Hypogonadotropic Hypogonadism

CONTEXT

Constitutional delay of puberty (CDP) is highly heritable, but the genetic basis for CDP is largely unknown. Idiopathic hypogonadotropic hypogonadism (IHH) can be caused by rare genetic variants, but in about half of cases, no rare-variant cause is found.

OBJECTIVE

To determine whether common genetic variants that influence pubertal timing contribute to CDP and IHH.

DESIGN

Case-control study.

PARTICIPANTS

80 individuals with CDP; 301 with normosmic IHH, and 348 with Kallmann syndrome (KS); control genotyping data from unrelated studies.

MAIN OUTCOME MEASURES

Polygenic scores (PGS) based on genome-wide association studies for timing of male pubertal hallmarks and age at menarche (AAM).

RESULTS

The CDP cohort had higher PGS for male pubertal hallmarks and for AAM compared to controls (for male hallmarks, Cohen's d = 0.67, P = 1 × 10-10; for AAM, d = 0.85, P = 1 × 10-16). The normosmic IHH cohort also had higher PGS for male hallmarks compared to controls, but the difference was smaller (male hallmarks d = 0.20, P = .003; AAM d = 0.10, P = .055). No differences were seen for the KS cohort compared to controls (male hallmarks d = 0.05, P = .45; AAM d = 0.03, P = .56).

CONCLUSION

Common genetic variants that influence pubertal timing in the general population contribute strongly to the genetics of CDP, weakly to normosmic IHH, and potentially not at all to KS. These findings demonstrate that the common-variant genetics of CDP and normosmic IHH are largely but not entirely distinct.

Age at Menarche and Coronary Artery Disease Risk: Divergent Associations with Different Sources of Variation

Background

In women, both earlier and later age at menarche (AAM) are associated with increased risk of coronary artery disease (CAD). This study sought to determine if the relationship of AAM with CAD and CAD risk factors differs for different underlying sources of variation in AAM - specifically, variation attributable to common genetic variants as represented by a polygenic score (PGS) vs. variation in AAM adjusted for the PGS.

Methods

Primary analyses were conducted on data from 201,037 women in the UK Biobank and validation studies on data from 23,268 women in the Women's Genome Health Study (WGHS). For each individual, a PGS for AAM was calculated, then two variables were estimated from linear regression models: the genetically predicted AAM (the estimated AAM for each woman solely due to the effects of common genetic variants) and the PGS-adjusted AAM (estimated AAM for each woman solely due to factors other than the PGS). Logistic regression and linear splines were then used to study the relationships of these variables with CAD and CAD risk factors.

Results

Genetically predicted AAM demonstrated a linear relationship with CAD and linear or roughly linear relationships with CAD risk factors. In contrast, PGS-adjusted AAM demonstrated a U-shaped relationship with CAD and with hemoglobin A1c, triglycerides, HDL-C, and waist-hip ratio. Validation studies using WGHS data produced similar results.

Conclusions

These results suggest that later AAM itself does not cause increased risk of CAD; rather, upstream sources of variation other than common genetic variants can cause both later AAM and increased risk of CAD. Dysglycemia, dyslipidemia, and central adiposity are candidate mediators of the association of later AAM with increased risk of CAD.

The genetic architecture of age at menarche and its causal effects on other traits

Age at menarche (AAM) is a sign of puberty of females. It is a heritable trait associated with various adult diseases. However, the genetic mechanism that determines AAM and links it to disease risk is poorly understood. Aiming to uncover the genetic basis for AAM, we conducted a joint association study in up to 438,089 women from 3 genome-wide association studies of European and East Asian ancestries. A series of bioinformatical analyses and causal inference were then followed to explore in-depth annotations at the associated loci and infer the causal relationship between AAM and other complex traits/diseases. This largest meta-analysis identified a total of 21 novel AAM associated loci at the genome wide significance level (P < 5.0  × 10-8), 4 of which were European ancestry-specific loci. Functional annotations prioritized 33 candidate genes at newly identified loci. Significant genetic correlations were observed between AAM and 67 complex traits. Further causal inference demonstrated the effects of AAM on 13 traits, including forced vital capacity (FVC), high blood pressure, age at first live birth, etc, indicating that earlier AAM causes lower FVC, worse lung function, hypertension and earlier age at first (last) live birth. Enrichment analysis identified 5 enriched tissues, including the hypothalamus middle, hypothalamo hypophyseal system, neurosecretory systems, hypothalamus and retina. Our findings may provide useful insights that elucidate the mechanisms determining AAM and the genetic interplay between AAM and some traits of women.

Genetics of female and male reproductive traits and their relationship with health, longevity and consequences for offspring

Substantial shifts in reproductive behaviors have recently taken place in many high-income countries including earlier age at menarche, advanced age at childbearing, rising childlessness and a lower number of children. As reproduction shifts to later ages, genetic factors may become increasingly important. Although monogenic genetic effects are known, the genetics underlying human reproductive traits are complex, with both causal effects and statistical bias often confounded by socioeconomic factors. Here, we review genome-wide association studies (GWASs) of 44 reproductive traits of both female and male individuals from 2007 to early 2024, examining reproductive behavior, reproductive lifespan and aging, infertility and hormonal concentration. Using the GWAS Catalog as a basis, from 159 relevant studies, we isolate 37 genes that harbor association signals for four or more reproductive traits, more than half of which are linked to rare Mendelian disorders, including ten genes linked to reproductive-related disorders: FSHB, MCM8, DNAH2, WNT4, ESR1, IGSF1, THRB, BRWD1, CYP19A1 and PTPRF. We also review the relationship of reproductive genetics to related health and behavioral traits, aging and longevity and the effect of parental age on offspring outcomes as well as reflecting on limitations, open questions and challenges in this fast-moving field.

Genetically Determined Plasma Docosahexaenoic Acid Showed a Causal Association with Female Reproductive Longevity-Related Phenotype: A Mendelian Randomization Study

BACKGROUND

Female reproductive aging remains irreversible. More evidence is needed on how polyunsaturated fatty acids (PUFAs) affect the female reproductive lifespan.

OBJECTIVES

To identify and validate specific PUFAs that can influence the timing of menarche and menopause in women.

METHODS

We utilized a two-sample Mendelian randomization (MR) framework to evaluate the causal relationships between various PUFAs and female reproductive longevity, defined by age at menarche (AAM) and age at natural menopause (ANM). Our analyses leveraged summary statistics from four genome-wide association studies (GWASs) on the plasma concentrations of 10 plasma PUFAs, including 8866 to 121,633 European individuals and 1361 East Asian individuals. Large-scale GWASs for reproductive traits provided the genetic data of AAM and ANM from over 202,323 European females and 43,861 East Asian females. Causal effects were estimated by beta coefficients, representing, for each increase in the standard deviation (SD) of plasma PUFA concentration, the yearly increase in AAM or ANM. Replications, meta-analyses, and cross-ancestry effects were assessed to validate the inference.

CONCLUSIONS

Higher plasma DHA was identified to be associated with delayed natural menopause without affecting menarche, offering a potential intervention target for extending reproductive longevity.

BMI Interacts with the Genome to Regulate Gene Expression Globally, with Emphasis in the Brain and Gut

Genome-wide association studies identify common genomic variants associated with disease across a population. Individual environmental effects are often not included, despite evidence that environment mediates genomic regulation of higher order biology. Body mass index (BMI) is associated with complex disorders across clinical specialties, yet has not been modeled as a genomic environment. Here, we tested for expression quantitative trait (eQTL) loci that contextually regulate gene expression across the BMI spectrum using an interaction approach. We parsed the impact of cell type, enhancer interactions, and created novel BMI-dynamic gene expression predictor models. We found that BMI main effects associated with endocrine gene expression, while interactive variant-by-BMI effects impacted gene expression in the brain and gut. Cortical BMI-dynamic loci were experimentally dysregulated by inflammatory cytokines in an in vitro system. Using BMI-dynamic models, we identify novel genes in nitric oxide signaling pathways in the nucleus accumbens significantly associated with depression and smoking. While neither genetics nor BMI are sufficient as standalone measures to capture the complexity of downstream cellular consequences, including environment powers disease gene discovery.

The Relationship Between PM2.5 and Eight Common Lung Diseases: A Two-Sample Mendelian Randomization Analysis

Air pollutants have both acute and chronic impacts on human health, affecting multiple systems and organs. While PM2.5 exposure is commonly assumed to be strongly associated with all respiratory diseases, this relationship has not been systematically analyzed. This study employed a two-sample Mendelian randomization approach to investigate the effects of PM2.5 on eight common lung diseases, using data from GWAS. Additionally, multivariable Mendelian randomization was applied to assess the direct effects of various air pollutants and the mediating roles of common factors such as BMI and smoking. At a significance threshold of 5×10-8, PM2.5 showed a significant causal relationship with both asthma and COPD. When the screening threshold was relaxed to 5× 10-6, this exposure continued to demonstrate significant associations not only with asthma and COPD, but also with other respiratory diseases, including pneumonia, emphysema/chronic bronchitis, and lung cancer. In the multivariable Mendelian randomization analysis, which controlled for smoking and bacterial infections, the association with pneumonia became non-significant, while the relationships with the other four diseases persisted. This study provides a systematic exploration of the relationship between PM2.5 and eight pulmonary diseases from a new perspective, deepening our understanding of the impact of air pollution on health and laying the foundation for future efforts to mitigate these effects.

Sex hormones and reproductive factors with cardiac arrhythmia and ECG indices: a mendelian randomization study

BACKGROUND

Sex is a determinant of the incidence and etiology of arrhythmia. Observational and basic studies suggest that sex hormones are essential in this process; however, the relationship between sex hormones and arrhythmia remains unclear. Mendelian randomization (MR) was used to investigate the causal relationships between sex hormone levels, arrhythmia, and electrocardiographic (ECG) indices.

METHODS

Large genome-wide association studies (GWAS) data on sex hormones, stratified by sex, from the UK biobank consortium, were used as exposure data, and data on atrial fibrillation (AF), atrioventricular block, sick sinus syndrome, paroxysmal tachycardia, and ECG indices were obtained from the FinnGen consortium and summarized large GWAS data. Inverse variance weighting or wald odds was used as the primary analytical method, and weighted medians and MR-Egger regression were used for complementary analyses. The results of the MR of sex hormones and AF from different sources were analyzed using a meta-analysis. Summary-data-based MR analysis was utilized to explore the relationship between sex-hormone related drugs and arrhythmia.

RESULTS

In men, genetically predicted higher estradiol concentrations were associated with a lower risk of AF (odds ratio: 0.908 [0.852-0.967]; p = 0.0029], whereas genetically predicted higher concentrations of total testosterone were associated with lower heart rate variability. Sex hormones showed no association with atrioventricular block, sick sinus syndrome, paroxysmal tachycardia, resting heart rate, P wave duration, P wave terminal force in lead V1 [PTFV1], PR interval, QRS duration, QTc [QT interval corrected by heart rate], ST duration, spatial [spQRSTa] and frontal [fQRSTa] QRS-T angles in males. In females, there was no significant evidence that sex hormones are associated with arrhythmias or ECG indices.

CONCLUSION

In this study, we identified a potential causal relationship between estradiol and the risk of AF in males. However, there was no significant association between sex hormones and either arrhythmias or ECG indices in females. These results suggested that sex hormones may play a limited role in cardiac arrhythmias, which requires further verification.

Society for endocrinology guideline for understanding, diagnosing and treating female hypogonadism

Female hypogonadism (FH) is a relatively common endocrine disorder in women of premenopausal age, but there are significant uncertainties and wide variation in its management. Most current guidelines are monospecialty and only address premature ovarian insufficiency (POI); some allude to management in very brief and general terms, and most rely upon the extrapolation of evidence from the studies relating to physiological estrogen deficiency in postmenopausal women. The Society for Endocrinology commissioned new guidance to provide all care providers with a multidisciplinary perspective on managing patients with all forms of FH. It has been compiled using expertise from Endocrinology, Primary Care, Gynaecology and Reproductive Health practices, with contributions from expert patients and a patient support group, to help clinicians best manage FH resulting from both POI and hypothalamo-pituitary disorders, whether organic or functional.

Age, sex, and cell type-resolved hypothalamic gene expression across the pubertal transition in mice

BACKGROUND

The hypothalamus plays a central role in regulating puberty. However, our knowledge of the postnatal gene regulatory networks that control the pubertal transition in males and females is incomplete. Here, we investigate the age-, sex- and cell-type-specific gene regulation in the hypothalamus across the pubertal transition.

METHODS

We used RNA-seq to profile hypothalamic gene expression in male and female mice at five time points spanning the onset of puberty (postnatal days (PD) 12, 22, 27, 32, and 37). By combining this data with hypothalamic single nuclei RNA-seq data from pre- and postpubertal mice, we assigned gene expression changes to their most likely cell types of origin. In our colony, pubertal onset occurs earlier in male mice, allowing us to focus on genes whose expression is dynamic across ages and offset between sexes, and to explore the bases of sex effects.

RESULTS

Our age-by-sex pattern of expression enriched for biological pathways involved hormone production, neuronal activation, and glial maturation. Additionally, we inferred a robust expansion of oligodendrocytes precursor cells into mature oligodendrocytes spanning the prepubertal (PD12) to peri-pubertal (PD27) timepoints. Using spatial transcriptomic data from postpubertal mice, we observed the lateral hypothalamic area and zona incerta were the most oligodendrocyte-rich regions and that these cells expressed genes known to be involved in pubertal regulation.

CONCLUSION

Together, by incorporating multiple biological timepoints and using sex as a variable, we identified gene and cell-type changes that may participate in orchestrating the pubertal transition and provided a resource for future studies of postnatal hypothalamic gene regulation.

Epigenome-wide association study of fluoride exposure during early adolescence and DNA methylation among U.S. children

Exposure to fluoride in early childhood has been associated with altered cognition, intelligence, attention, and neurobehavior. Fluoride-related neurodevelopment effects have been shown to vary by sex and very little is known about the mechanistic processes involved. There is limited research on how fluoride exposure impacts the epigenome, potentially leading to changes in DNA methylation of specific genes regulating key developmental processes. In the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS), urine samples were analyzed using a microdiffusion method to determine childhood urinary fluoride adjusted for specific gravity (CUFsg) concentrations. Whole blood DNA methylation was assessed using the Infinium MethylationEPIC BeadChip 850 k Array. In a cross-sectional analysis, we interrogated epigenome-wide DNA methylation at 775,141 CpG loci across the methylome in relation to CUFsg concentrations in 272 early adolescents at age 12 years. Among all participants, higher concentrations of CUF were associated with differential methylation of one CpG (p < 6 × 10-8) located in the gene body of GBF1 (cg25435255). Among females, higher concentrations of CUFsg were associated with differential methylation of 7 CpGs; only three CpGs were differentially methylated among males with no overlap of significant CpGs observed among females. Secondary analyses revealed several differentially methylated regions (DMRs) and CpG loci mapping to genes with key roles in psychiatric outcomes, social interaction, and cognition, as well as immunologic and metabolic phenotypes. While fluoride exposure may impact the epigenome during early adolescence, the functional consequences of these changes are unclear warranting further investigation.

Genetically inferred birthweight, height, and puberty timing and risk of osteosarcoma

INTRODUCTION

Several studies have linked increased risk of osteosarcoma with tall stature, high birthweight, and early puberty, although evidence is inconsistent. We used genetic risk scores (GRS) based on established genetic loci for these traits and evaluated associations between genetically inferred birthweight, height, and puberty timing with osteosarcoma.

METHODS

Using genotype data from two genome-wide association studies, totaling 1039 cases and 2923 controls of European ancestry, association analyses were conducted using logistic regression for each study and meta-analyzed to estimate pooled odds ratios (ORs) and 95% confidence intervals (CIs). Subgroup analyses were conducted by case diagnosis age, metastasis status, tumor location, tumor histology, and presence of a known pathogenic variant in a cancer susceptibility gene.

RESULTS

Genetically inferred higher birthweight was associated with an increased risk of osteosarcoma (OR =1.59, 95% CI 1.07-2.38, P = 0.02). This association was strongest in cases without metastatic disease (OR =2.46, 95% CI 1.44-4.19, P = 9.5 ×10-04). Although there was no overall association between osteosarcoma and genetically inferred taller stature (OR=1.06, 95% CI 0.96-1.17, P = 0.28), the GRS for taller stature was associated with an increased risk of osteosarcoma in 154 cases with a known pathogenic cancer susceptibility gene variant (OR=1.29, 95% CI 1.03-1.63, P = 0.03). There were no significant associations between the GRS for puberty timing and osteosarcoma.

CONCLUSION

A genetic propensity to higher birthweight was associated with increased osteosarcoma risk, suggesting that shared genetic factors or biological pathways that affect birthweight may contribute to osteosarcoma pathogenesis.

Lack of a genetic risk continuum between pubertal timing in the general population and idiopathic hypogonadotropic hypogonadism

Pubertal timing is a highly heritable trait in the general population. Recently, a large-scale exome-wide association study has implicated rare variants in six genes (KDM4C, MC3R, MKRN3, PDE10A, TACR3, and ZNF483) as genetic determinants of pubertal timing within the general population. Two of the genes (TACR3, MKRN3) are already implicated in extreme disorders of pubertal timing. This observation suggests that there may be a pervasive "genetic risk continuum" wherein genes that govern pubertal timing in the general population, by extension, may also be causal for rare Mendelian disorders of pubertal timing. Hence, we hypothesized that the four novel genes linked to pubertal timing in the population will also contribute to idiopathic hypogonadotropic hypogonadism (IHH), a genetic disorder characterized by absent puberty. Exome sequencing data from 1322 unrelated IHH probands were reviewed for rare sequence variants (RSVs) (minor allele frequency bins: <1%; <0.1%; <0.01%) in the six genes linked to puberty in the general population. A gene-based rare variant association testing (RVAT) was performed between the IHH cohort and a reference public genomic sequences repository-the Genome Aggregation Database (gnomAD). As expected, RVAT analysis showed that RSVs in TACR3, a known IHH gene, were significantly enriched in the IHH cohort compared to gnomAD cohort across all three MAF bins. However, RVAT analysis of the remaining five genes failed to show any RSV enrichment in the IHH cohort across all MAF bins. Our findings argue strongly against a pervasive genetic risk continuum between pubertal timing in the general population and extreme pubertal phenotypes. The biologic basis of such distinct genetic architectures' merits further evaluation.

High Carbohydrate, Fat, and Protein Diets Have a Critical Role in Folliculogenesis and Oocyte Development in Rats

To date, there is no comparative data on the effects of carbohydrates, fat, and proteins, which are macronutrients, on female reproductive functions. Therefore, in this study, we investigated the effects of diets enriched with carbohydrates, fats, and proteins on folliculogenesis and oocyte development in female rats. 21-day-old rats that were just weaned were divided into 4 groups: control, carbohydrate, fat, and protein. The control group was fed with standard chow and the carbohydrate, fat, and protein groups were fed diets enriched with 75% carbohydrate, 60% fat, and 50% protein for 11 weeks, respectively. It was found that high-fat and high-protein diets caused an increase in the estrous cycle length compared to carbohydrate group (p < 0.05). Graafian follicle number decreased in the protein group compared to the control (p < 0.05). However, the atretic follicle number was higher in the fat group compared to the control group (p < 0.05). In the carbohydrate group, Zp1 was found to be lower than the control and protein groups, Zp2 was found to be lower than the control, and Zp3 was found to be lower than the fat group (p < 0.05). While BMP15 was similar between groups (p > 0.05), GDF9 was lower in all diet groups compared to the control (p < 0.05). Foxo3a was lower in the protein group compared to carbohydrate and control (p < 0.05). GAS2 was found to be higher in the control group than the fat group, and higher in the carbohydrate group than the fat and protein groups (p < 0.05). FSH, LH, Progesterone, and E2 levels were higher in all three diet groups than in the control (p < 0.05). Also, significant differences were observed between the groups regarding adiponectin, resistin, and leptin levels. Taken together, high carbohydrate, fat, and protein intake are associated with impairment of the menstrual cycle, depletion of the developing follicle types, and altered expression of folliculogenesis-specific genes and hormones. Therefore, long-term macronutrient diets may result in shortened reproductive periods and reduced fertilization potential in females in the long run.

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 associations with disease in populations with Indigenous American ancestries

The genetic architecture of complex diseases affecting populations with Indigenous American ancestries is poorly understood due to their underrepresentation in genomics studies. While most of the genetic diversity associated with disease trait variation is shared among worldwide populations, a fraction of this component is expected to be unique to each continental group, including Indigenous Americans. Here, I describe the current state of knowledge from genome-wide association studies on Indigenous populations, as well as non-Indigenous populations with partial Indigenous ancestries from the American continent, focusing on disease susceptibility and anthropometric traits. While some studies identified risk alleles unique to Indigenous populations, their effects on trait variation are mostly small. I suggest that the associations rendered by many inter-population studies are probably inflated due to the absence of socio-cultural-economic covariates in the association models. I encourage the inclusion of admixed individuals in future GWAS studies to control for inter-ancestry differences in environmental factors. I suggest that some complex diseases might have arisen as trade-off costs of adaptations to past evolutionary selective pressures. Finally, I discuss how expanding panels with Indigenous ancestries in GWAS studies is key to accurately assess genetic risk in populations from the American continent, thus decreasing global health disparities.

Genetic links between ovarian ageing, cancer risk and de novo mutation rates

Human genetic studies of common variants have provided substantial insight into the biological mechanisms that govern ovarian ageing1. Here we report analyses of rare protein-coding variants in 106,973 women from the UK Biobank study, implicating genes with effects around five times larger than previously found for common variants (ETAA1, ZNF518A, PNPLA8, PALB2 and SAMHD1). The SAMHD1 association reinforces the link between ovarian ageing and cancer susceptibility1, with damaging germline variants being associated with extended reproductive lifespan and increased all-cause cancer risk in both men and women. Protein-truncating variants in ZNF518A are associated with shorter reproductive lifespan-that is, earlier age at menopause (by 5.61 years) and later age at menarche (by 0.56 years). Finally, using 8,089 sequenced trios from the 100,000 Genomes Project (100kGP), we observe that common genetic variants associated with earlier ovarian ageing associate with an increased rate of maternally derived de novo mutations. Although we were unable to replicate the finding in independent samples from the deCODE study, it is consistent with the expected role of DNA damage response genes in maintaining the genetic integrity of germ cells. This study provides evidence of genetic links between age of menopause and cancer risk.

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.

Evaluation and comparison of nine growth and development-based measures of pubertal timing

BACKGROUND

Pubertal timing is heritable, varies between individuals, and has implications for life-course health. There are many different indicators of pubertal timing, and how they relate to each other is unclear. Our aim was to quantitatively compare nine indicators of pubertal timing.

METHODS

We used data from questionnaires and height, weight, and bone measurements from ages 7-17 y in a population-based cohort of 4267 females and 4251 males to compare nine growth and development-based indicators of pubertal timing. We summarise age of each indicator, their phenotypic and genetic correlations, and how they relate to established genetic risk score (GRS) for puberty timing, and phenotypic childhood body composition measures.

RESULTS

We show that pubic hair in males (mean: 12.6 y) and breasts in females (11.5 y) are early indicators of puberty, and voice breaking (14.2 y) and menarche (12.7 y) are late indicators however, there is substantial variation between individuals in pubertal age. All indicators show evidence of positive phenotypic intercorrelations (e.g., r = 0.49: male genitalia and pubic hair ages), and positive genetic intercorrelations. An age at menarche GRS positively associates with all other pubertal age indicators (e.g., difference in female age at peak height velocity per SD higher GRS: 0.24 y, 95%CI: 0.21 to 0.26), as does an age at voice breaking GRS (e.g., difference in age at male axillary hair: 0.11 y, 0.07 to 0.15). Higher childhood fat mass and lean mass associated with earlier puberty timing.

CONCLUSIONS

Our findings provide insights into the measurements of the timing of pubertal growth and development and illustrate value of various pubertal timing indicators in life-course research.

Prenatal, newborn and childhood factors and the timing of puberty in boys and girls

BACKGROUND

Our aim was to determine if prenatal factors, gestational age, birth weight and length, and childhood body mass index (BMI) are associated with the timing of puberty.

METHODS

Our population-based study comprised 4826 girls and 5112 boys born between 1997 and 2002. Multiple linear regression modeled the relationships between the maternal and child predictors and the age at peak height velocity (PHV).

RESULTS

Maternal smoking throughout pregnancy was associated with earlier age at PHV (-1.8 months in girls, 95%CI = -3.2 to -0.3, p = 0.015 and -1.7 months in boys, 95%CI = -3.1 to -0.3, p = 0.016). Older gestational age predicted later age at PHV in boys. One SDS increase in birth weight led to 1.7 months later age at PHV in girls (95%CI = 1.2 to 2.2, p < 0.001) and 0.8 months in boys (95%CI = 0.2 to 1.3, p = 0.005). At the age of 9 years, each increment of BMI by 1 kg/m2 was associated with 1.7 months (95%CI = -1.9 to -1.6, p < 0.001) and 1.3 months (95%CI = -1.4 to -1.1, p < 0.001) earlier age at PHV in girls and boys, respectively.

CONCLUSIONS

Fetal exposure to smoking can potentially exert enduring effects on pubertal timing. Birth weight and childhood nutritional status are significant determinants of pubertal timing in both sexes.

IMPACT

Maternal smoking was associated with earlier timing of puberty and greater birth weight with later timing of puberty in both girls and boys. Most previous studies have focused on girls and used surveys to assess pubertal development, but we studied both sexes and used the same objective measure (age at peak height velocity) for the timing of puberty. Our study increases knowledge especially regarding factors associated with the timing of puberty among boys.

Study of rs7759938, rs314280, and rs314276 Polymorphisms of LIN28B in Relation to Age at Menarche in Girls of Greek Descent

BACKGROUND

Single-nucleotide polymorphisms in LIN28B, critical regulators of female growth and puberty, have been linked to age at menarche.

METHODS

We assessed the association of rs7759938, rs314280, and rs314276 with menarcheal age in girls of Greek descent. We reviewed the records of 248 girls who had their first menstruation before 18 years and who attended the Greek Departments of Pediatric Endocrinology from January 2021 to July 2023. Genotyping was performed by standard DNA-based methods. Association analyses involved both parametric and non-parametric tests.

RESULTS

The average age of breast and pubic hair development was 9.95 years, and the age at menarche was 11.55 years. Menarche occurred ≤11 years (mean 10.24 years) in 108 girls (43.5%) and >11 years (mean 12.55 years) in 140 (56.5%). The girls' menarcheal age correlated significantly with that of their mothers (average 12.1 years, p-value < 0.0001, Spearman's r 0.350). The dominant rs7759938(TT) genotype was the most common (55.2%), followed by the dominant rs314276(CC) (53.2%) and dominant rs314280(TT) (14.5%) genotypes.

CONCLUSIONS

There was no association between age at menarche and any of the polymorphism genotypes/alleles or between genotypes/alleles and birth weight, gestational week, mode of delivery, and maternal age at menarche. Future large sample studies are warranted to confirm these results.

Body Mass Index and Hypertension as Mediators of the Association Between Age at Menarche and Subclinical Atherosclerosis: A Sex-Specific Mendelian Randomization Analysis

BACKGROUND

Early age at menarche (AAM) has been associated with a higher risk of carotid artery intima-media thickness (cIMT), an indicator of subclinical vascular disease, albeit the mechanisms underlying this association remain elusive. A better understanding of the relationship between AAM, modifiable cardiometabolic risk factors, and subclinical atherosclerosis may contribute to improved primary prevention and cardiovascular disease treatment. We aimed to investigate the putative causal role of AAM on cIMT, and to identify and quantify the potentially mediatory effects of cardiometabolic risk factors underlying this relationship.

METHODS AND RESULTS

We conducted linkage disequilibrium score regression analyses between our exposure of interest, AAM, our outcome of interest, cIMT and potential mediators of the AAM-cIMT association to gauge cross-trait genetic overlap. We considered as mediators the modifiable anthropometric risk factors body mass index (BMI), systolic blood pressure (SBP), lipid traits (total cholesterol, triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol), and glycemic traits (fasting glucose). We then leveraged the paradigm of Mendelian randomization to infer causality between AAM and cIMT, and to identify whether cardiometabolic risk factors served as potential mediators of this effect. Our analyses showed that genetically predicted AAM was inversely associated with cIMT, BMI, SBP, and triglycerides, and positively associated with high-density lipoprotein, low-density lipoprotein, and total cholesterol. We showed that the effect of genetically predicted AAM on cIMT may be partially mediated through BMI (20.1% [95% CI, 1.4% to 38.9%]) and SBP (13.5% [95% CI, 0.5%-26.6%]). Our cluster-specific Mendelian randomization revealed heterogeneous causal effect estimates of age at menarche on BMI and SBP.

CONCLUSIONS

We highlight supporting evidence for a potential causal association between earlier AAM and cIMT, and almost one third of the effect of AAM on cIMT may be mediated by BMI and SBP. Early intervention aimed at lowering BMI and hypertension may be beneficial in reducing the risk of developing subclinical atherosclerosis due to earlier age at menarche.

No relationship between male pubertal timing and depression - new insights from epidemiology and Mendelian randomization

BACKGROUND

In males, the relationship between pubertal timing and depression is understudied and less consistent than in females, likely for reasons of unmeasured confounding. To clarify this relationship, a combined epidemiological and genetic approach was chosen to exploit the methodological advantages of both approaches.

METHODS

Data from 2026 males from a nationwide, representative study were used to investigate the non-/linear relationship between pubertal timing defined by the age at voice break and depression, considering a multitude of potential confounders and their interactions with pubertal timing. This analysis was complemented by Mendelian randomization (MR), which is robust to inferential problems inherent to epidemiological studies. We used 71 single nucleotide polymorphisms related to pubertal timing in males as instrumental variable to clarify its causal relationship with depression based on data from 807 553 individuals (246 363 cases and 561 190 controls) by univariable and multivariable MR, including BMI as pleiotropic phenotype.

RESULTS

Univariable MR indicated a causal effect of pubertal timing on depression risk (inverse-variance weighted: OR 0.93, 95%-CI [0.87-0.99)], p = 0.03). However, this was not confirmed by multivariable MR (inverse-variance weighted: OR 0.95, 95%-CI [0.88-1.02)], p = 0.13), consistent with the epidemiological approach (OR 1.01, 95%-CI [0.81-1.26], p = 0.93). Instead, the multivariable MR study indicated a causal relationship of BMI with depression by two of three methods.

CONCLUSIONS

Pubertal timing is not related to MDD risk in males.

Understanding the genetic complexity of puberty timing across the allele frequency spectrum

Pubertal timing varies considerably and is associated with later health outcomes. We performed multi-ancestry genetic analyses on ~800,000 women, identifying 1,080 signals for age at menarche. Collectively, these explained 11% of trait variance in an independent sample. Women at the top and bottom 1% of polygenic risk exhibited ~11 and ~14-fold higher risks of delayed and precocious puberty, respectively. We identified several genes harboring rare loss-of-function variants in ~200,000 women, including variants in ZNF483, which abolished the impact of polygenic risk. Variant-to-gene mapping approaches and mouse gonadotropin-releasing hormone neuron RNA sequencing implicated 665 genes, including an uncharacterized G-protein-coupled receptor, GPR83, which amplified the signaling of MC3R, a key nutritional sensor. Shared signals with menopause timing at genes involved in DNA damage response suggest that the ovarian reserve might signal centrally to trigger puberty. We also highlight body size-dependent and independent mechanisms that potentially link reproductive timing to later life disease.

Relationship between age at menarche and breast cancer in individuals, as well as in first-degree kin and estrogen receptor status: a Mendelian randomization study

Target

We executed a Mendelian randomization (MR) investigation employing two distinct cohorts of genetic instrumental variables to elucidate the causal nexus between age at menarche (AAM) and the incidence of disparate breast cancer (BC) subtypes, in addition to the incidence of BC among first-degree kin.

Methods

We aggregated statistical data pertaining to AAM and BC from various consortia representing a homogenous population cohort. MR analysis was conducted employing inverse variance weighted (IVW) methodology as the principal approach, complemented by weighted median and MR-Egger regression techniques for an exhaustive evaluation. To evaluate the presence of pleiotropy, we applied the MR-Egger intercept test, MR-PRESSO, and leave-one-out sensitivity analysis.

Results

Upon exclusion of confounding SNP, an increment of one standard deviation in AAM was inversely correlated with the incidence of BC. (odds ratio [OR] 0.896, 95% confidence interval [CI] 0.831-0.968)/(OR 0.998, 95% CI 0.996-0.999) and estrogen receptor-positive (ER+) BC incidence (OR 0.895, 95% CI 0.814-0.983). It was also associated with reducing the risk of maternal BC incidence (OR 0.995, 95% CI 0.990-0.999) and sibling BC incidence (OR 0.997, 95% CI 0.994-0.999). No significant association was found between AAM and estrogen receptor-negative (ER-) BC incidence (OR 0.936, 95% CI 0.845-1.037).

Conclusion

Our study substantiated the causal relationship between a delayed AAM and a diminished risk of BC in probands, as well as in their maternal progenitors and siblings. Furthermore, the analysis suggests that AAM exerts a considerable potential causal influence on the risk of developing Luminal-a/b subtype of BC.