An understanding of the inner workings of the placenta is imperative to elucidate how the maternal and fetal compartments coordinate to mediate fetal development. The two compartments can be separated and studied before term in sheep, a feat not possible in humans, thus providing a valuable translational model. This study investigated differential expression of gene signaling networks in the maternal and fetal compartments of the placenta and explored the potential influence of fetal sex. On approximately gestational day 120 (term: 147 days), ewes were euthanized and fetuses removed and sexed. Placentomes [n = 5 male, n = 3 female] were collected, and caruncles (maternal) and cotyledons (fetal) were separated and sequenced to assess RNA expression. Analysis revealed 2627 differentially expressed genes (FDR<0.01, abslog2FC ≥ 2) contributing to key transcriptional differences between maternal and fetal compartments, which suggested that the maternal compartment drives extracellular signaling at the interface whereas the fetal compartment controls internal mechanisms crucial for fetal-placental development. X-chromosome inactivation equalized expression of a vast majority of X-linked genes in the fetal compartment. Additionally, the female placenta had more fine-tuned regulation of key pathways for fetal-placental development, such as DNA replication, mRNA surveillance, and RNA transport, compared to males, which had enrichment of metabolic pathways including TCA cycle and galactose metabolism. These findings, in addition to supporting differences in expression in the maternal and fetal placental compartments and the possible influence of fetal sex, offer a transcriptional platform to compare placental perturbations that occur at the maternal-fetal interface that contribute to adverse pregnancy outcomes.

Inborn errors of immunity are monogenic disorders of the immune system that lead to immune deficiency and/or dysregulation in patients. Identification of precise genetic causes of disease aids diagnosis and advances our understanding of the human immune system; however, a significant portion of patients lack a molecular diagnosis. Somatic mosaicism, genetic changes in a subset of cells, is emerging as an important mechanism of immune disease in both young and older patients. Here, we review the current landscape of somatic genetic errors of immunity and methods for the detection and validation of somatic variants.

Males of polygynous mammals often do not live as long as females and, in some cases, exhibit evidence of earlier senescence. Patterns of DNA methylation (DNAm) have recently been used to predict chronological age in mammals. Whether DNAm also changes as a consequence of survival and senescence is largely untested in wild animals. In this study, we estimate mortality rates using recaptures of 2700 greater spear-nosed bats, Phyllostomus hastatus, over 34 years and DNAm profiled for over 300 adult bats. In this species, one male typically controls mating access to a group of unrelated females. Bayesian analysis reveals that mortality risk in males is 1.8 times that of females, and comparison of age-associated differences in DNAm indicates that DNAm changes 1.4 times faster in males than females. Therefore, even though the age of either sex is predicted by a common set of sites, the methylome of males is more dynamic than that of females. Sites associated with sex differences in the rate of DNAm change are sensitive to androgens and enriched on the X chromosome. Sites that exhibit hypermethylation are enriched in promoters of genes involved in the regulation of metabolic processes. Unexpectedly, subordinate males have higher mortality rates than reproductively dominant males and exhibit faster DNAm change than dominants at dozens of sites. Our results reveal that differences in mortality associated with sex and social status are reflected by changes in DNA methylation, providing novel insights into mechanisms of aging and mortality in this and likely other wild animal populations.

Sex differences in immunity are well-documented, though mechanisms underpinning these differences remain ill-defined. Here, in a human-only ex vivo study, we demonstrate that postpubertal cisgender females have higher levels of CD19+CD27+IgD- class-switched memory B cells compared with age-matched cisgender males. This increase is only observed after puberty and before menopause, suggesting a strong influence for sex hormones. Accordingly, B cells express high levels of estrogen receptor 2 (ESR2), and class-switch-regulating genes are enriched for ESR2-binding sites. In a gender-diverse cohort, blockade of natal estrogen in transgender males (XX karyotype) reduced class-switched memory B cell frequency, while gender-affirming estradiol treatment in transgender females (XY karyotype) did not increase these levels. In postmenopausal cis-females, class-switched memory B cells were increased in those taking hormone replacement therapy (HRT) compared with those who were not. These data demonstrate that sex hormones and chromosomes work in tandem to impact immune responses, with estrogen only influencing the frequency of class-switched memory B cells in individuals with an XX chromosomal background.

Asthma is a prevalent chronic condition, affecting an estimated 260 million people worldwide, according to the 2021 Global Burden of Disease Study. This condition significantly impacts individuals of all ages. One notable finding is that asthma prevalence among adults was higher in females than males. Recent evidence suggests that these disparities in asthma prevalence and outcomes are likely due to complex interactions among hormonal, anatomical, and environmental factors, coupled with societal and behavioral influences. The interchangeable use of the terms "sex" and "gender" in the scientific literature is frequently inconsistent. Biological sex is defined by anatomical and physiological characteristics determined by genetics; "gender", on the other hand, is a more complex construct and a universally accepted definition is still lacking. This lack of clarity, coupled with potential knowledge gaps, misunderstandings, or the inherent difficulty in differentiating sex- and gender-related effects, often leads to the terms being poorly defined or used interchangeably. Such imprecise usage hinders accurate data interpretation and research progress. This paper provides a perspective review synthesizing current knowledge regarding the influence of sex and gender on asthma, specifically focusing on their impact on disease pathogenesis, clinical presentation, severity, and management strategies.

Atherosclerosis, a chronic inflammatory condition driving coronary artery disease (CAD), manifests in two primary plaque types: unstable atheromatous plaques and stable fibrous plaques. While significant research has focused on atheromatous plaques, recent studies emphasize the growing importance of fibrous plaques, particularly in females under 50 years of age, where erosion on fibrous plaques significantly contributes to coronary thrombosis. The molecular mechanisms underlying sex differences in atherosclerotic plaque characteristics, including vascular smooth muscle cell (VSMC) contributions, remain understudied. Therefore, we utilized sex-specific gene regulatory networks (GRNs) derived from VSMC gene expression data from 119 male and 32 female heart transplant donors to identify molecular drivers of fibrous plaques. GRN analysis revealed two female-biased networks in VSMC, GRN floralwhite and GRN yellowgreen , enriched for inflammatory signaling and actin remodeling pathways, respectively. Single-cell RNA sequencing of carotid plaques from female and male patients confirmed the sex specificity of these networks in VSMCs. Further sub cellular phenotyping of the single-cell RNA sequencing revealed a sex-specific gene expression signature within GRN yellowgreen for VSMCs enriched for contractile and vasculature development pathways. Bayesian network modeling of the GRN yellowgreen identified MYH9 as a key driver gene. Indeed, elevated MYH9 protein expression in atherosclerotic plaques was associated with higher smooth muscle cell content and lower lipid content in female plaques, suggesting its involvement in fibrous plaque formation. Further proteomic analysis confirmed MYH9's upregulation in female fibrous plaques only and its correlation with stable plaque features. These findings provide novel insights into sex-specific molecular mechanisms regulating fibrous plaque formation.

Many autoimmune diseases exhibit a strong female bias. While sex hormones may influence sex bias in disease, recent studies suggest that the X chromosome itself directly contributes to female-biased susceptibility to autoimmunity. Females with two X chromosomes utilize X Chromosome Inactivation (XCI) to silence gene expression from one X chromosome, equalizing expression between the sexes. The X chromosome is highly enriched with immune-related genes, and recent work indicates that the fidelity of XCI maintenance in lymphocytes from female systemic lupus erythematosus patients is compromised, suggesting that aberrant X-linked gene expression contributes to autoimmune phenotypes. XCI is initiated and maintained by the long noncoding RNA XIST/Xist through its interactions with the inactive X chromosome and numerous interacting proteins, and recent studies also implicate XIST/Xist RNA in driving endosomal Toll-like receptor signaling and XIST/Xist RNA-protein complexes in serving as a source of autoantigens to respectively drive autoimmunity. Here, we will review these three distinct pathways that underscore the significance of X-linked genetics for understanding the origins of the female bias in autoimmune disease.

Klinefelter syndrome (KS), characterized by the presence of at least one extra X-chromosome, is a common cause of male infertility. However, the mechanism underlying the failure of germline specification is not well studied. Intriguingly, the differentiation efficiency of female human pluripotent stem cells (hPSCs) is often lower than that of male. This study investigates how X-linked gene dosage affects human primordial germ cell-like cells (hPGCLCs) specification in both healthy and diseased conditions. This work reveals that X-linked genes play a multifaceted role against the fate competency to hPGCLCs, with escape genes IGSF1 and CHRDL1 inhibiting the TGF-beta/Activin A and BMP pathways, respectively. Notably, this work identifies a previously unrecognized role of SOX2, upregulated by the escape gene USP9X, elucidating a species-specific function in the mammalian germline. The USP9X-SOX2 regulatory axis profoundly influenced cellular metabolism, mitochondrial morphology, and progenitor competence in hPGCLCs specification. Furthermore, the inability to downregulate SOX2 and upregulate SOX17 in response to BMP signaling impedes downstream gene activation due to motif binding competition. These findings shed novel insights into the human germline specification by elucidating the divergent roles of SOX2 versus SOX17 in mammals, influenced by X-linked gene dosage effects. These results offer potential applications for improving the induction efficiency of hPGCLCs, facilitating disease mechanistic studies.

Aging leads to progressive decline in organ and tissue integrity and function, partly due to loss of proteostasis and autophagy malfunctioning. A decrease with age in chaperone-mediated autophagy (CMA), a selective type of lysosomal degradation, has been reported in various organs and cells from rodents and humans. Disruption of CMA recapitulates features of aging, whereas activating CMA in mice protects against age-related diseases such as Alzheimer's, retinal degeneration and/or atherosclerosis. However, sex-specific and cell-type-specific differences in CMA with aging remain unexplored. Here, using CMA reporter mice and single-cell transcriptomic data, we report that most organs and cell types show CMA decline with age, with males exhibiting a greater decline with aging. Reduced CMA is often associated with fewer lysosomes competent for CMA. Transcriptional downregulation of CMA genes may further contribute to CMA decline, especially in males. These findings suggest that CMA differences may influence organ vulnerability to age-related degeneration.

The nasal microbiome may influence host risk for COVID-19 by modulating the expression of key proteins that facilitate SARS-CoV-2 entry, including angiotensin-converting enzyme 2 (ACE2), which binds the virus, and transmembrane serine protease 2 (TMPRSS2), which activates viral entry into nasal epithelial cells. This study examined whether the expression levels of ACE2 and TMPRSS2 in the nasal cavity predict the risk of SARS-CoV-2 infection and whether the host nasal microbiome modulates their expression.

Using 1548 self-collected nasal swabs from a population-based surveillance testing of community-dwelling adults in Washington D.C., we conducted two retrospective case-control studies (cross-sectional: n = 111 cases and 343 controls; longitudinal: n = 97 cases, 286 controls) and a nasal microbiome study (n = 428). Cases, defined as individuals with a positive SARS-CoV-2 test, were matched with controls based on age and test date. Pre-infection samples were analysed. We measured nasal ACE2/TMPRSS2 expression using RT-qPCR and characterized the nasal microbiome using 16S rRNA gene-based qPCR and sequencing. We used machine learning and regression analysis to determine if nasal ACE2/TMPRSS2 expression predicts SARS-CoV-2 infection and whether the nasal microbiome influences their expression.

Elevated nasal ACE2/TMPRSS2 expression was associated with 3.6-fold increased risk of contracting COVID-19 (95% CI = 1.71-7.47) compared to those with no detectable levels of ACE2 or TMPRSS2. Before testing positive for SARS-CoV-2, cases also had significantly higher and more unstable ACE2/TMPRSS2 expression in their nasal cavity than controls. Having high densities of Staphylococcus aureus, Haemophilus influenzae, or Moraxella catarrhalis/nonliquefaciens was linked to increased nasal ACE2/TMPRSS2 expression. In contrast, having high densities of Dolosigranulum pigrum was associated with decreased nasal ACE2/TMPRSS2 expression.

These results suggest that natural variation in the nasal microbiome significantly impacts ACE2/TMPRSS2 expression in the nasal cavity and the near-term risk of SARS-CoV-2 infection in adults. Modifying the nasal microbiome could potentially reduce COVID-19 risk.

Research reported in this article was supported by the Milken Institute School of Public Health, the George Washington University and the National Institute of Allergy and Infectious Diseases, National Institutes of Health under award number R01AI168182. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Female human induced pluripotent stem cells frequently undergo X-chromosome inactivation (XCI) erosion, marked by X-inactive specific transcript (XIST) RNA loss and partial reactivation of the inactive X (Xi). This overlooked phenomenon limits our understanding of its impact on stem cell applications. Here, we show that XCI erosion is frequent and heterogeneous, leading to the reactivation of several X-linked genes. These are primarily located on the short arm of the X chromosome, particularly near escape genes and within H3K27me3-enriched domains, with reactivation linked to reduced promoter DNA methylation. Interestingly, escape genes further increase their expression from Xi upon XCI erosion, highlighting the critical role of XIST in their dosage regulation. Importantly, global (hydroxy)methylation levels and imprinted regions remain unaffected, and analysis of trilineage commitment and cardiomyocyte formation reveals that XCI erosion persists across differentiation. These findings underscore the need for greater awareness of the implications of XCI erosion for stem cell research and clinical applications.

X chromosome inactivation (XCI) equalizes X-linked gene expression between sexes. B cells exhibit dynamic XCI, with Xist RNA/heterochromatic marks absent on the inactive X (Xi) in naive B cells but returning following mitogenic stimulation. The impact of dynamic XCI on Xi structure and maintenance was previously unknown. Here, we find dosage compensation of the Xi with state-specific XCI escape genes in naive and in vitro-activated B cells. Allele-specific OligoPaints indicate similar Xi and active X (Xa) territories in B cells that are less compact than in fibroblasts. Allele-specific Hi-C reveals a lack of TAD-like structures on the Xi of naive B cells and stimulation-induced alterations in TAD-like boundary strength independent of gene expression. Notably, Xist deletion in B cells changes TAD boundaries and large-scale Xi compaction. Altogether, our results uncover B cell-specific Xi plasticity, which could underlie sex-biased biological mechanisms.

Loss of chromosome Y (LOY) occurs in aging and cancers, but its extent and implications in human embryonic stem cells (hESCs) have not been studied. Here, we analyzed over 2,650 RNA sequencing (RNA-seq) samples from hESCs and their differentiated derivatives to detect LOY. We found that 12% of hESC samples have lost their chromosome Y and identified LOY in all three germ layers. Differential expression analysis revealed that LOY samples showed a decrease in expression of pluripotency markers and in ribosomal protein (RP) genes. Strikingly, significant RP transcription downregulation was observed in most RP genes, although there is only one expressed Y-linked RP gene. We further analyzed RP expression in Turner syndrome and Diamond-Blackfan anemia samples and observed overall downregulation of RP transcription. This broad analysis sheds light on the scope and effects of LOY in hESCs, suggesting a novel dosage-sensitive mechanism regulating RP gene transcription in LOY and autosomal ribosomopathies.

Pre-existing respiratory diseases may influence coronavirus disease (COVID-19) susceptibility and severity. However, the molecular mechanisms underlying the airway epithelial response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection severity in patients with chronic respiratory diseases remain unelucidated. Using an in vitro model of differentiated primary bronchial epithelial cells, we aimed to investigate the molecular mechanisms of SARS-CoV-2 infection in pre-existing cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). Our study revealed reduced susceptibility of CF and COPD airway epithelia to SARS-CoV-2, relative to that in healthy controls. Mechanistically, reduced transmembrane serine protease 2 (TMPRSS2) activity potentially contributed to this resistance of CF epithelium. Upregulated complement and inflammatory pathways in CF and COPD epithelia potentially primed the antiviral state prior to infection. Analysis of a COVID-19 patient cohort validated our findings, correlating specific inflammatory markers (IP-10, SERPINA1, and CFB) with COVID-19 severity. This study elucidates SARS-CoV-2 pathogenesis and identifies potential biomarkers for clinical monitoring.

The biological mechanisms underlying the increased prevalence of Alzheimer's disease (AD) in women remain undefined. While previous case/control studies have identified sex-biased molecular pathways, the sex-specific relationships between gene expression and AD endophenotypes, particularly involving sex chromosomes, are underexplored. With bulk transcriptomic data across 3 brain regions from 767 decedents, we investigated sex-specific associations between gene expression and post-mortem β-amyloid and tau, as well as antemortem longitudinal cognition. Among 23,118 significant gene associations, 10% were sex-specific, with 73% of these identified in females and primarily associated with tau tangles and longitudinal cognition (90%). Notably, four X-linked genes, MCF2, HDAC8, FTX, and SLC10A3, demonstrated significant sex differences in their associations with AD endophenotypes (i.e., significant sex × gene interaction). Our results also uncovered sex-specific biological pathways, including a female-specific role of neuroinflammation and neuronal development, underscoring the importance of sex-aware analyses to advance precision medicine approaches in AD.

Viable human aneuploidy can be challenging to model in rodents due to syntenic boundaries or primate-specific biology. Human monosomy-X (45,X) causes Turner syndrome (TS), altering craniofacial, skeletal, endocrine, and cardiovascular development, which in contrast remain unaffected in X-monosomic mice. To learn how monosomy-X may impact embryonic development, we turned to 45,X and isogenic euploid human induced pluripotent stem cells (hiPSCs) from male and female mosaic donors. Because the neural crest (NC) is hypothesized to give rise to craniofacial and cardiovascular changes in TS, we assessed differential expression of hiPSC-derived anterior NC cells (NCCs). Across three independent isogenic panels, 45,X NCCs show impaired acquisition of PAX7+SOX10+ markers and disrupted expression of other NCC-specific genes relative to isogenic euploid controls. Additionally, 45,X NCCs increase cholesterol biosynthesis genes while reducing transcripts with 5' terminal oligopyrimidine (TOP) motifs, including those of ribosomal and nuclear-encoded mitochondrial proteins. Such metabolic pathways are also over-represented in weighted co-expression modules that are preserved in monogenic neurocristopathy and reflect 28% of all TS-associated terms of the human phenotype ontology. We demonstrate that 45,X NCCs reduce protein synthesis despite activation of mammalian target of rapamycin (mTOR) but are partially rescued by mild mTOR suppression. Our analysis identifies specific sex-linked genes that are expressed from two copies in euploid males and females alike and qualify as candidate haploinsufficient drivers of TS phenotypes in NC-derived lineages. This study demonstrates that isogenic hiPSC-derived NCC panels representing monosomy-X can serve as powerful models of early NC development in TS and inform new hypotheses toward its etiology.

Studying sex effects and their underlying mechanisms is of major relevance to understanding brain health. Despite growing interests, experimentally studying sex differences, particularly in the context of aging, remains challenging. Since sex chromosomal content influences gonadal development, separating the effects of gonadal hormones and chromosomal factors requires specific model systems. Here, we highlight rodent and tractable models for examining sex dimorphism in brain and cognitive aging. In addition, we discuss multi-omic and bioinformatic approaches that yield biological insights from animal and human studies. This review provides a comprehensive overview of the diverse toolkit now available to advance our understanding of sex differences in brain aging.

The human placenta is distinct from most organs due to its uniquely low-methylated genome. DNA methylation (DNAme) is particularly depleted in the placenta at partially methylated domains and on the inactive X chromosome (Xi) in XX samples. While Xi DNAme is known to be critical for X-chromosome inactivation (XCI) in other tissues, its role in the placenta remains unclear. Understanding X-linked DNAme variation in the placenta may provide insights into XCI and have implications for prenatal development and phenotypic sex differences.

DNAme data were analyzed from over 350 human placental (chorionic villus) samples, along with samples from cord blood, amnion and chorion placental membranes, and fetal somatic tissues. We characterized X chromosome DNAme variation in the placenta relative to sample variables including cell composition, ancestry, maternal age, placental weight, and fetal birth weight, and compared these patterns to other tissues. We also evaluated the relationship between X-linked DNAme and previously reported XCI gene expression status in placenta.

Our findings confirm that the placenta exhibits significant depletion of DNAme on the Xi compared to other tissues. Additionally, we observe that X chromosome DNAme profiles in the placenta are influenced by cell composition, particularly trophoblast proportion, with minimal DNAme variation across gestation. Notably, low promoter DNAme is observed at most genes on the Xi regardless of XCI status, challenging known associations in somatic tissues between low promoter DNAme and escape from XCI.

This study provides evidence that the human placenta has a distinct Xi DNAme landscape, which may inform our understanding of sex differences during prenatal development. Future research should explore the mechanisms underlying the placenta's unique X-linked DNAme profile, and the factors involved in placental XCI maintenance.

Systemic sclerosis (SSc) is an autoimmune disease that has a strong female predominance. Both the X-linked TLR7 and TLR8 can induce type I IFN (IFN-I) by plasmacytoid DCs (pDCs), which can promote fibrosis. We identified five subclusters of pDCs, including ISGhigh clusters that were over-represented in SSc patients. We observed that both TLR7 and TLR8 genes escape from X chromosome inactivation (XCI) at higher frequency in pDCs of SSc patients, which was associated with changes in TLR7 protein profile. Combined DNA/RNA FISH analysis revealed that the TLR7/8 locus is preferentially located outside of the inactive X (Xi) territory when TLR7 is expressed, suggesting that higher-order loop formation is linked to TLR7/8 expression from the Xi. Furthermore, the expression levels of XIST and the transcriptional repressor SPEN were reduced in SSc pDCs. Hence, our data revealed the heterogeneity of pDCs in SSc and suggested that altered XCI at the TLR7/8 locus may contribute to the chronic IFN-I activity of pDCs in female SSc patients.

Genes that escape X-chromosome inactivation (XCI) in female somatic cells vary in number and levels of escape among mammalian species and tissues, potentially contributing to species- and tissue-specific sex differences. CTCF, a master chromatin conformation regulator, is enriched at escape regions and may play an important role in regulating escape, but the molecular mechanisms remain elusive.

CTCF binding profiles and epigenetic features were systematically examined at escape genes (escapees) using mouse allelic systems with skewed XCI to distinguish the inactive X (Xi) and active X (Xa) chromosomes. We found that six constitutive and two facultative escapees are located inside 30-800 kb domains marked by convergent arrays of CTCF binding sites, consistent with the formation of chromatin loops. Facultative escapees show clear differences in CTCF binding depending on their XCI status in specific cell types/tissues. In addition, sets of strong and in some cases divergent CTCF binding sites located at the boundary between an escapee and its adjacent neighbors subject to XCI would also help insulate domains. Indeed, deletion but not inversion of a CTCF binding site at the boundary between the facultative escapee Car5b and its silent neighbor Siah1b results in a dramatic reduction of Car5b escape. This is associated with reduced CTCF and cohesin binding, which indicates loss of looping and insulation and is supported by 3C combined with Hi-C analysis. In addition, enrichment in the repressive mark H3K27me3 invades the Car5b domain in deleted cells, consistent with loss of expression from the Xi. In contrast, cells with an inversion of the CTCF binding site retain CTCF and cohesin binding, as well as looping, in line with persistence of escape. Interestingly, the levels of escape increase in cells with deletion of either Dxz4, which disrupts the Xi-specific compact 3D structure, or Firre, which results in lower H3K27me3 enrichment on the Xi, indicating that the structural and epigenetic features of the Xi constrain escape from XCI in wild type conditions.

Taken together, our findings support the idea that escape from XCI in female somatic cells is modulated by both the topological insulation of domains via CTCF binding and the surrounding heterochromatin environment.

Sex chromosomes are a fundamental aspect of sex-biased biology, but the extent to which homologous X-Y gene pairs ('the gametologs') contribute to sex-biased phenotypes remains hotly debated. Although these genes tend to exhibit large sex differences in expression throughout the body (XX females can express both X members, and XY males can express one X and one Y member), there is conflicting evidence regarding the degree of functional divergence between the X and Y members. Here we develop and apply co-expression fingerprint analysis to characterize functional divergence between the X and Y members of 17 gametolog gene pairs across >40 human tissues. Gametolog pairs exhibit functional divergence between the sexes that is driven by divergence between the X versus Y members (assayed in males), and this within-pair divergence is greatest among pairs with evolutionarily distant X and Y members. These patterns reflect that X versus Y gametologs show coordinated patterns of asymmetric coupling with large sets of autosomal genes, which are enriched for functional pathways and gene sets implicated in sex-biased biology and disease. Our findings suggest that the X versus Y gametologs have diverged in function and prioritize specific gametolog pairs for future targeted experimental studies.

Aortic aneurysm is a common cardiovascular disease. Over time, the disease damages the structural and functional integrity of the aorta, causing it to abnormally expand and potentially rupture, which can be fatal. Sex differences are evident in the disease, with men experiencing an earlier onset and higher incidence. However, women may face a worse prognosis and a higher risk of rupture. While there are some studies on the cellular and molecular mechanisms of aneurysm formation, it remains unclear how sex factors contribute to sexual dimorphism. Therefore, this review aims to summarize the role of sex in the occurrence of aortic aneurysms, offering valuable insights for disease prevention and the development of appropriate treatment options.

Cell states are influenced by the regulation of gene expression orchestrated by transcription factors capable of binding to accessible DNA regions. To uncover if sex differences exist in chromatin accessibility in the human dorsal root ganglion (hDRG), where nociceptive neurons innervating the body are found, we performed bulk and spatial assays for transposase-accessible chromatin technology followed by sequencing (ATAC-seq) from organ donors without a history of chronic pain. Using bulk ATAC-seq, we detected abundant sex differences in the hDRG. In women, differentially accessible regions (DARs) mapped mostly to the X chromosome, whereas in men, they mapped to autosomal genes. Hormone-responsive transcription factor binding motifs such as EGR1/3 were abundant within DARs in women, while JUN, FOS, and other activating protein 1 factor motifs were enriched in men, suggesting a higher activation state of cells compared with women. These observations were consistent with spatial ATAC-seq data. Furthermore, we validated that EGR1 expression is biased to female hDRG using RNAscope. In neurons, spatial ATAC-seq revealed higher chromatin accessibility in GABAergic, glutamatergic, and interferon-related genes in women and in Ca2+-signaling-related genes in men. Strikingly, XIST, responsible for inactivating 1 X chromosome by compacting it and maintaining at the periphery of the nucleus, was found to be highly dispersed in female neuronal nuclei. This is likely related to the higher chromatin accessibility in X in female hDRG neurons observed using both ATAC-seq approaches. We have documented baseline epigenomic sex differences in the hDRG which provide important descriptive information to test future hypotheses.

The XG blood group system comprises two antigens, Xga and CD99. CD99 is known to be carried on both the X and Y chromosomes in pseudoautosomal region 1. We identified five unrelated Japanese individuals with anti-CD99 and investigated their genomic background as well as the clinical significance of anti-CD99.

Analysis of CD99 expression on RBCs and a modified monocyte monolayer assay was performed using flow cytometry. Genomic DNA was obtained from the five anti-CD99 producers to identify the deleted region responsible for the lack of CD99, and we conducted a long polymerase chain reaction using primer pairs specific for CD99 and GYG2.

CD99 expression from the Y chromosome was higher than that from the X chromosome. The five anti-CD99 plasma samples gave varied agglutination strengths with the red blood cells (RBCs) expressing high and low CD99 levels, in the antiglobulin test. The phagocytosis rate of anti-CD99-sensitized RBCs was 76.6% in one case indicating a risk of hemolytic transfusion reactions (HTR), and it correlated with the level of CD99 expression. The deleted region spanned 115 kb, from CD99 exon 3 to GYG2 exon 1. All five anti-CD99 producers were homozygous for the large deletion allele.

All five anti-CD99 producers were females with a history of pregnancy in Kyushu, Japan, and this deletion allele may thus be endemic. Our results indicated the possibility of HTR due to anti-CD99, and the risk is low when transfusing RBC products from Xg(a-) females with a low expression of CD99.

Mutations in the AVPR2 gene are the most common cause of nephrogenic diabetes insipidus (NDI). In-frame deletions of the AVPR2 gene are a rare variant that results in NDI. We report a novel variant of the p.H138del in an NDI family with twin male patients and three female carriers of different clinical phenotypes.

The proband's blood genome was sequenced with a panel, and the variants were classified according to ACMG/AMP (2015) guidelines. X chromosome inactivation (XCI) was analyzed in the peripheral blood of his mother, grandmother, and maternal aunt, respectively. The haplotypes of the X chromosome were determined using their STR loci.

A novel in-frame deletion in the AVPR2 gene was detected in monozygotic-twin boys, and his mother, grandmother, and maternal aunt were heterozygous carriers. The two boys showed typical NDI, and their mother and grandmother presented polydipsia, polydipsia, and polyuria, but the maternal aunt did not have similar symptoms. The blood XCI results of the mother, grandmother, and maternal aunt showed random inactivation (36.18 , 48.37, and 49.30 %, respectively). The X haplotype indicated that the variant of the mother and grandmother was on their activated X chromosomes(Xa), while the maternal aunt's variant was on her inactivated X chromosome(Xi).

In-frame deletion of the AVPR2 gene within its functional domain can significantly affect protein function, which is one of the vital causes of NDI. The clinical variability of female carriers of AVPR2 is associated with underlying environmental and epigenetic factors or complex recombination of the X chromosomes.

X-chromosome inactivation (XCI) is a fundamental mechanism in placental mammals that compensates for gene dosage differences between sexes. Using methylation levels of genes under XCI, we establish defective levels of XCI as a new source of interindividual variation among cancer types in females, characterized by a significant and consistent lowering of XIST expression and enrichment of differentially expressed genes under XCI. We show that defective XCI is an additive factor to the cancer risk of XCI escape deregulation in women. Defective XCI of more than 10% has an attributable risk of 40% among 12 different cancers from The Cancer Genome Atlas. Validations between independent studies of breast cancer samples show that defective XCI increases triple-negative subtype frequency, decreases survival rates, and is reduced by chemotherapy treatment. Mechanistically, it is associated with somatic mutations at TP53 and top MYC gains. In independent studies, defective XCI is detectable in blood and increases with aging, menopause, and cancer diagnosis.

To evaluate the association of GGN repeat polymorphism of androgen receptor (AR) with ovarian reserve and ovarian response in controlled ovarian stimulation (COS).

This genetic association study was conducted among a total of 361 women aged ≤40 years with basal FSH≤12 U/L undergoing the GnRH-agonist long protocol for COS in a university-affiliated IVF center. GGN repeat in the AR gene was analyzed with Sanger sequencing. The primary endpoint was the number of antral follicle counts (AFCs), and the secondary endpoints were stimulation days, total dose of gonadotropin (Gn) used, total number of retrieved oocytes, ovarian sensitivity index, and follicular output rate.

The GGN repeat in exon 1 of the AR gene ranged from 13 to 24, and the median repeat length was 22. Based on the genotypes (S for GGN repeats <22, L for GGN repeats ≥22), the patients were divided into 3 groups: SS, SL, and LL. Generalized regression analysis indicated that the number of AFCs in group SS was significantly lower than those in group SL (adjusted β=1.8, 95% CI: 0.2-3.4, P=0.024) and group LL (adjusted β=1.5, 95% CI: 0.2-2.7, P=0.021). No significant difference was observed in the number of AFCs between group SL and group LL (P>0.05). Generalized regression analysis indicated no significant differences in ovarian stimulation parameters among the 3 groups, either before or after adjusting for confounding factors (P>0.05).

GGN repeat length on the AR gene is associated with AFC but not with ovarian response in Chinese women, indicating that AR gene polymorphisms may affect ovarian reserve.

Coronavirus disease 2019 (COVID-19) is a multi-system disease that can lead to various severe complications. Acute limb ischemia (ALI) has been increasingly recognized as a COVID-19-associated complication that often predicts a poor prognosis. However, the pathophysiology and molecular mechanisms underlying COVID-19-associated ALI remain poorly understood. Hypercoagulability and thrombosis are considered important mechanisms, but we also emphasize the roles of vasospasm, hypoxia, and acidosis in the pathogenesis of the disease. The angiotensin-converting enzyme 2 (ACE2) pathway, inflammation, and platelet activation may be important molecular mechanisms underlying these pathological changes induced by COVID-19. Furthermore, we discuss the hypotheses of risk factors for COVID-19-associated ALI from genetic, age, and gender perspectives based on our analysis of molecular mechanisms. Additionally, we summarize therapeutic approaches such as use of the interleukin-6 (IL-6) blocker tocilizumab, calcium channel blockers, and angiotensin-converting enzyme inhibitors, providing insights for the future treatment of coronavirus-associated limb ischemic diseases.

Sex differences in brain development are thought to lead to sex variation in social behavior. Sex differences are fundamentally driven by both gonadal hormones and sex chromosomes, yet little is known about the independent effects of each on social behavior. Further, mouse models of the genetic liability for the neurodevelopmental disorder MYT1L Syndrome have shown sex-specific deficits in social motivation. In this study, we aimed to determine if gonadal hormones or sex chromosomes primarily mediate the sex differences seen in mouse social behavior, both at baseline and in the context of Myt1l haploinsufficiency.

Four-core genotypes (FCG) mice, which uncouple gonadal and chromosomal sex, were crossed with MYT1L heterozygous mice to create eight different groups with unique combinations of sex factors and MYT1L genotype. A total of 131 mice from all eight groups were assayed for activity and social behavior via the open field and social operant paradigms. Measures of social seeking and orienting were analyzed for main effects of chromosome, gonads, and their interactions with Myt1l mutation.

The FCGxMYT1L cross revealed independent effects of both gonadal and chromosomal sex on activity and social behavior. Specifically, the presence of ovarian hormones led to greater overall activity, social seeking, and social orienting regardless of MYT1L genotype. In contrast, sex chromosomes affected social behavior mainly in the MYT1L heterozygous group, with XX MYT1L mutant mice demonstrating elevated levels of social orienting and seeking compared to XY MYT1L mutant mice.

Gonadal and chromosomal sex have independent mechanisms of driving greater social motivation in females. Additionally, genes on the sex chromosomes may interact with neurodevelopmental risk genes to influence sex variation in atypical social behavior.

ACE2 expression is altered in pregnancy disorders and ACE2 gene variants are associated with several major pregnancy complications including small-for-gestational-age, fetal growth restriction and preeclampsia. This study utilised gene-editing to generate both ACE2 knockout and ACE2 rs2074192 placental organoids, facilitating mechanistic studies into the role of ACE2 in placental development, and the effect of fetal carriage of ACE2 rs2074192 CC, CT and TT genotypes. Parameters of cell and organoid growth were measured, together with qPCR, Western Blotting, and ELISA assessments, in all groups from both organoid models. Here, we report that ACE2 knockout results in delayed placental cell growth and increased cell death. ACE2 knockout organoids had lower ACE protein expression, reduced organoid diameters and asymmetrical growth. Placental organoids with the ACE2 rs2074192 TT genotype had significantly higher expression of ACE2 mRNA and ACE2 protein with elevated ACE2:ACE expression ratio and no change in ACE protein. Despite increased expression of ACE2 protein, ACE2 enzyme activity was significantly decreased in ACE2 rs2074192 TT placental organoids. TT organoids also had reduced diameters and asymmetrical growth. Our research provides a new molecular understanding of the role of ACE2 in placental development, with potential implications for pregnancy in the carriage of the ACE2 rs2074192 gene variant.

Turner syndrome (TS) presents with multiple karyotypes, including 45,X monosomy and variants such as isochromosomes and mosaicism, and is characterized by several co-morbidities, including metabolic conditions and autoimmunity. Here, we investigated the genomic landscapes across a range of karyotypes. We show that TS have a common autosomal methylome and transcriptome, despite distinct karyotypic variations. All TS individuals lacked the X chromosome p-arm, and XIST expression from the q-arm did not affect the autosomal transcriptome or methylome, highlighting the critical role of the missing p-arm with its pseudoautosomal region 1. Furthermore, we show increased levels of neutrophils and increased neutrophil activation. The increase in neutrophils was linked to TS clinical traits and to increased expression of the X-Y homologous gene TBL1X, suggesting a genetic basis, which may lead to neutrophil-driven inflammatory stress in TS. Identifying TS individuals with increased neutrophil activation could potentially mitigate the progression towards more severe metabolic issues.

The incidence of pituitary adrenocorticotropic hormone (ACTH)-secreting PitNETs, commonly known as ACTH PitNETs, is significantly higher in females; however, the underlying causes for this gender disparity remain unclear. In this study, we analyzed the expression of deubiquitinating enzymes in functioning ACTH PitNETs from both male and female subjects using RNA sequencing and identified USP11 as a potential susceptibility factor contributing to the higher prevalence of these PitNETs in females. Further investigation revealed that USP11 expression is markedly elevated in female functioning ACTH PitNETs, with levels significantly higher than those observed in male PitNETs and normal pituitary tissue. Experimental data indicate that USP11 promotes the transcription of proopiomelanocortin (POMC) and the secretion of ACTH. In contrast, knockdown of USP11 leads to a substantial reduction in both POMC transcription and ACTH secretion, as demonstrated in both in vitro and in vivo models. Mechanistically, we found that USP11 facilitates the deubiquitination of the key transcription factor TPIT in functioning ACTH PitNETs, enhancing its protein stability and thereby promoting POMC transcription and ACTH secretion. Additionally, virtual screening identified Lomitapide and Nicergoline as potential inhibitors of USP11, reducing POMC expression and ACTH secretion. Thus, USP11 emerges as a potential therapeutic target, and drugs aimed at inhibiting its function could benefit women with Cushing's disease.

X Chromosome Inactivation (XCI) equalizes X-linked gene expression between sexes. B cells exhibit dynamic XCI, with Xist RNA/heterochromatic marks absent on the inactive X (Xi) in naive B cells but returning following mitogenic stimulation. The impact of dynamic XCI on Xi structure and maintenance was previously unknown. Here, we find dosage compensation of the Xi with state-specific XCI escape genes in naive and in vitro activated B cells. Allele-specific OligoPaints indicate similar Xi and Xa territories in B cells that are less compact than in fibroblasts. Allele-specific Hi-C reveals a lack of TAD-like structures on the Xi of naive B cells, and stimulation-induced alterations in TAD-like boundary strength independent of gene expression. Notably, Xist deletion in B cells changes TAD boundaries and large-scale Xi compaction. Altogether, our results uncover B cell-specific Xi plasticity which could underlie sex-biased biological mechanisms.

Human fetuses exhibit notable sex differences in growth rate and response to the intrauterine environment, yet their origins and underlying mechanisms remain uncertain. Here, we conduct a detailed investigation of sex differences in human pre-gastrulation embryos. The lower methylation and incomplete inactivation of the X chromosome in females, as well as the sex-specific cell-cell communication patterns, contribute to sex-differential transcription. Male trophectoderm is more inclined toward syncytiotrophoblast differentiation and exhibits a stronger hormone secretion capacity, while female trophectoderm tends to retain cytotrophoblast program with stronger mitochondrial function as well as higher vasculogenesis and immunotolerance signals. Male primitive endoderm initiates the anterior visceral endoderm transcriptional program earlier than females. The cell cycle activities of the epiblast and primitive endoderm are higher in males compared to females, while the situation is opposite in the trophectoderm. In conclusion, our study provides in-depth insights into the sex differences in human pre-gastrulation embryos and contributes to unraveling the origins of the sex differences in human fetal development.

Transient Bartter syndrome related to pathogenic variants of MAGED2 is the most recently described antenatal Bartter syndrome. Despite its transient nature, it is the most severe form of Bartter syndrome in the perinatal period. Our aim was to describe 14 new cases and to try to explain the incomplete penetrance in women.

We report on 14 new cases, including 3 females, and review the 40 cases described to date. We tested the hypothesis that MAGED2 is transcriptionally regulated by differential methylation of its CpG-rich promotor by pyrosequencing of DNA samples extracted from fetal and adult leukocytes and kidney samples.

Analysis of the data from 54 symptomatic patients showed spontaneous resolution of symptoms in 27% of cases, persistent complications in 41% of cases, and fatality in 32% of cases. Clinical anomalies were reported in 76% of patients, mostly renal anomalies (52%), cardiovascular anomalies (29%), and dysmorphic features (13%). A developmental delay was reported in 24% of patients. Variants were found in all regions of the gene. Methylation analysis of the MAGED2 CpG-rich promotor showed a correlation with gender, independent of age, tissue or presence of symptoms, excluding a role for this mechanism in the incomplete penetrance in women.

This work enriches the phenotypic and genetic description of this recently described disease and deepens our understanding of the pathophysiological role and regulation of MAGED2. Finally, by describing the wide range of outcomes in patients, this work opens the discussion on genetic counseling offered to families.