Biological factors underlying sex differences in neurological disorders

Expression of Dopamine-Related Genes in Four Human Brain Regions

A better understanding of dopaminergic gene expression will inform future treatment options for many different neurologic and psychiatric conditions. Here, we utilized the National Institutes of Health’s Genotype-Tissue Expression project (GTEx) dataset to investigate genotype by expression associations in seven dopamine pathway genes (ANKK1, DBH, DRD1, DRD2, DRD3, DRD5, and SLC6A3) in and across four human brain tissues (prefrontal cortex, nucleus accumbens, substantia nigra, and hippocampus). We found that age alters expression of DRD1 in the nucleus accumbens and prefrontal cortex, DRD3 in the nucleus accumbens, and DRD5 in the hippocampus and prefrontal cortex. Sex was associated with expression of DRD5 in substantia nigra and hippocampus, and SLC6A3 in substantia nigra. We found that three linkage disequilibrium blocks of SNPs, all located in DRD2, were associated with alterations in expression across all four tissues. These demographic characteristic associations and these variants should be further investigated for use in screening, diagnosis, and future treatment of neurological and psychiatric conditions.

Aging and sex: Impact on microglia phagocytosis

Microglia dysfunction and activation are important hallmarks of the aging brain and are concomitant with age-related neurodegeneration and cognitive decline. Age-associated changes in microglia migration and phagocytic capacity result in maladaptive responses, chronic neuroinflammation, and worsened outcomes in neurodegenerative disorders. Given the sex bias in the incidence, prevalence, and therapy response of most neurological disorders, we have here examined whether the phagocytic activity of aged microglia is different in males and females. With this aim, the phagocytosis activity of male and female cells was compared in an in vitro aged microglia model and in microglia isolated from adult (5-month-old) or aged (18-month-old) mice. In both models, the phagocytosis of neural debris increased with aging in male and female cells and was higher in aged female microglia than in aged male cells. However, female aged microglia lost its ability to adapt its phagocytic activity to inflammatory conditions. These findings suggest that microglia phagocytosis of neural debris may represent a previously unexplored neuroprotective characteristic of aged microglia that may contribute to the generation of sex differences in the manifestation of neurodegenerative diseases.

APOE rs405509 polymorphism and Parkinson's disease risk in the Chinese population

Parkinson's disease (PD) is the second most common progressive neurodegenerative disorder with complex etiology involving both genetic and environmental factors. Apolipoprotein E (ApoE) rs405509 (-219 T/G), a promoter SNP, controls the expression of APOE gene, and plays a modifier effect of APOE ε4 on the susceptibility of Alzheimer's disease. In this study, we investigate the association between APOE rs405509 polymorphism and the susceptibility of PD in a Chinese population. A total of 1020 subjects were collected including 510 sporadic PD patients (mean age: 63.11 ± 9.28 years) and 510 healthy control subjects (mean age: 62.97 ± 9.09 years). APOE rs405509 polymorphism was genotyped using a TaqMan genotyping method. The Hardy-Weinberg Equilibrium (HWE) was calculated for the control group by Chi-square (χ2) test. The strength of this association between the APOE rs405509 polymorphism and PD risk was evaluated with crude odds ratios (ORs) and 95 % confidence intervals (CIs) using a logistic regression analysis. The T allele frequency was 0.84 and 0.70 in the PD and control groups, respectively. T allele carriers of rs405509 were associated with an increased overall risk of PD and in male subjects in the allele, recessive, and additive genetic models. Similar results in female subjects were found in the allele and recessive genetic models. In conclusion, our study suggests that the APOE rs405509 T allele is correlated with increased susceptibility of PD in a Chinese population.

SeXX Matters in Multiple Sclerosis

Multiple sclerosis (MS) is the most common chronic inflammatory and neurodegenerative disease of the central nervous system (CNS). An interesting feature that this debilitating disease shares with many other inflammatory disorders is that susceptibility is higher in females than in males, with the risk of MS being three times higher in women compared to men. Nonetheless, while men have a decreased risk of developing MS, many studies suggest that males have a worse clinical outcome. MS exhibits an apparent sexual dimorphism in both the immune response and the pathophysiology of the CNS damage, ultimately affecting disease susceptibility and progression differently. Overall, women are predisposed to higher rates of inflammatory relapses than men, but men are more likely to manifest signs of disease progression and worse CNS damage. The observed sexual dimorphism in MS may be due to sex hormones and sex chromosomes, acting in parallel or combination. In this review, we outline current knowledge on the sexual dimorphism in MS and discuss the interplay of sex chromosomes, sex hormones, and the immune system in driving MS disease susceptibility and progression.

Evaluation of the efficacy of drug treatment based on measurement of the oxidative stress, using reactive oxygen metabolites and biological antioxidant potential, in children with autism spectrum disorder and attention deficit hyperactivity disorder

Background

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, mainly characterized by impairment of social communication and restricted interests. ASD is frequently accompanied by attention deficit hyperactivity disorder (ADHD), which is characterized by carelessness, hyperactivity and impulsivity (ASD/ADHD). It has been suggested that ASD and ADHD are associated with oxidative stress, that is, that patients with ASD/ADHD are in a state of increased oxidative stress. There are currenr tly no objective or biological test criteria for evaluating the efficacy of drug therapy in these patients. The purpose of this study was to evaluate whether oxidative stress markers [serum reactive oxygen metabolites (d-ROMs) levels and biological antioxidant potential (BAP)] can be used as objective indicators for evaluating the efficacy of drug treatment in ASD/ADHD patients.

Methods

The subjects of this study subjects were 50 Japanese patients with ASD/ADHD aged 4 to 14 years old. Serum samples were obtained from the patients to measure the serum levels of d-ROMs and the serum BAP. The study subjects were divided into two age groups: preschool children (4 to 6 years old) and school-age children (7 to 14 years old), and the serum levels of d-ROMs, serum BAP, serum BAP/d-ROMs ratio (hereinafter, the prefix serum will be dropped), and scores on the Parent-interview ASD Rating Scales-Text Revision (PARS-TR) and ADHD Rating Scale (ADHD-RS) were determined before and after drug therapy and compared between the two groups. In addition, changes in the d-ROMs, BAP and BAP/d-ROMs ratio and changes in the scores on the PARS-TR and ADHD-RS after treatment were also analyzed.

Results

Significant decrease of the d-ROMs, BAP, and scores on the PARS-TR and ADHD-RS, with a significant increase of the BAP/d-ROMs ratio, was observed after treatment. In addition, a significant correlation was observed between the changes in the d-ROMs and changes in the scores on the PARS-TR and ADHD-RS after treatment in the school-age ASD/ADHD children.

Conclusion

Our results suggest the possibility that the serum level of d-ROMs may be useful as an objective assessment marker to supplement the subjective assessment of the effects of drug treatment in school-age children with ASD/ADHD.

Temporal trends and geographical variability of the prevalence and incidence of attention deficit/hyperactivity disorder diagnoses among children in Catalonia, Spain

Attention deficit/hyperactivity disorder (ADHD) is one of the most common behavioral disorders in childhood. According to a recent systematic review, the worldwide estimate of ADHD prevalence is 7.2% in children. This study aims to assess the prevalence of ADHD diagnoses in 2017 and the incidence of ADHD diagnoses in 2009–2017 in children living in Catalonia, Spain, as well as their temporal and geographical variability, and stratifying by sex and age. We used administrative data for all children aged 4 to 17 years who were insured in the public Catalan Health System in 2009–2017. We identified all ADHD cases diagnosed in 2009–2017 (ICD-9 code 314). We estimated the prevalence of ADHD diagnoses in 2017 and the overall annual incidence of ADHD diagnoses in 2009–2017. We used Poisson regression models to assess temporal trends in the incidence. We estimated a prevalence of ADHD diagnoses of 4.06% (95%CI 4.03, 4.10) in 2017, being 5.81% (95%CI 5.75, 5.87) for boys and 2.20% (95%CI 2.16, 2.24) for girls, the highest prevalence being in 13-to-17-year-olds (7.28% (95%CI 7.20, 7.36)). We did not observe a statistically significant increase of the incidence of ADHD diagnoses during the study period. Geographical differences were found across the healthcare areas in both prevalence and annual incidence and constant during the study period. In conclusion, the prevalence of ADHD diagnoses observed in this study was 4.06%, which was lower than the estimates reported in previous systematic reviews, but in line with the prevalence estimates from other recent European studies. The prevalence was higher in boys than girls, with a sex ratio consistent with previous studies. We did not observe an increase in the temporal trend of incidence of ADHD diagnoses in recent years, but we found geographical differences.

Increased age and male sex are independently associated with higher frequency of blood-cerebrospinal fluid barrier dysfunction using the albumin quotient

Background

The cerebrospinal fluid (CSF)/serum quotient of albumin (QAlb) is the most used biomarker for the evaluation of blood–cerebrospinal fluid barrier (B-CSF-B) permeability. For years QAlb was considered only as an age-related parameter but recently it has also been associated to sex. The aim of the present study was to explore the impact of sex in the determination of B-CSF-B dysfunction.

Methods

The analysis was retrospectively conducted on subjects consecutively admitted to the neurological ward. CSF and serum albumin levels were measured by immunonephelometry and pathological QAlb thresholds were considered: 6.5 under 40 years, 8.0 in the age 40–60 and 9.0 over 60 years.

Results

1209 subjects were included in the study. 718 females and 491 males (age: 15–88 years): 24.6% of patients had a diagnosis of multiple sclerosis, 23.2% suffered from other inflammatory neurological diseases, 24.6% were affected by non-inflammatory neurological diseases, and for 27.6% of patients the final neurological diagnosis could not be traced. Dysfunctional B-CSF-B was detected more frequently (44 vs. 20.1%, p < 0.0001) and median QAlb value were higher (7.18 vs. 4.87, p < 0.0001) in males than in females in the overall study population and in all disease subgroups. QAlb and age were positively correlated both in female (p < 0.0001) and male (p < 0.0001) patients, however the slopes of the two regression lines were not significantly different (p = 0.7149), while the difference between the elevations was extremely significant (p < 0.0001) with a gap of 2.2 units between the two sexes. Finally, in a multivariable linear regression analysis increased age and male sex were independently associated with higher QAlb in the overall study population (both p < 0.001) and after stratification by age and disease group.

Conclusions

Accordingly, identification and validation of sex-targeted QAlb thresholds should be considered as a novel tool in an effort to achieve more precision in the medical approach.

CNVs and Chromosomal Aneuploidy in Patients With Early-Onset Schizophrenia and Bipolar Disorder: Genotype-Phenotype Associations

Introduction: Early-onset schizophrenia (EOS) and bipolar disorder (EOB) start before the age of 18 years and have a more severe clinical course, a worse prognosis, and a greater genetic loading compared to the late-onset forms. Copy number variations (CNVs) are an important genetic factor in the etiology of psychiatric disorders. Therefore, this study aimed to analyze CNVs in patients with EOS and EOB and to establish genotype-phenotype relationships for contiguous gene syndromes or genes affected by identified CNVs. Methods: Molecular karyotyping was performed in 45 patients, 38 with EOS and seven with EOB hospitalized between 2010 and 2017. The exclusion criteria were medical or neurological disorders or IQ under 70. Detected CNVs were analyzed according to the standards and guidelines of the American College of Medical Genetics. Result: Molecular karyotyping showed CNVs in four patients with EOS (encompassing the PAK2, ADAMTS3, and ADAMTSL1 genes, and the 16p11.2 microduplication syndrome) and in two patients with EOB (encompassing the ARHGAP11B and PRODH genes). In one patient with EOB, a chromosomal aneuploidy 47, XYY was found. Discussion: Our study is the first study of CNVs in EOS and EOB patients in Slovenia. Our findings support the association of the PAK2, ARHGAP11B, and PRODH genes with schizophrenia and/or bipolar disorder. To our knowledge, this is also the first report of a multiplication of the ADAMTSL1 gene and the smallest deletion of the PAK2 gene in a patient with EOS, and one of the few reports of the 47, XYY karyotype in a patient with EOB.

Genetics of sex differences in neuroanatomy and function

Sex differences are observed at many distinct biologic levels, such as in the anatomy and functioning of the brain, behavior, and susceptibility to neuropsychiatric disorders. Previously, these differences were believed to entirely result from the secretion of gonadal hormones; however, recent research has demonstrated that differences are also the consequence of direct or nonhormonal effects of genes located on the sex chromosomes. This chapter reviews the four core genotype model that separates the effects of hormones and sex chromosomes and highlights a few genes that are believed to be partly responsible for sex dimorphism of the brain, in particular, the Sry gene. Genetics of the brain's neurochemistry is discussed and the susceptibility to certain neurologic and psychiatric disorders is reviewed. Lastly, we discuss the sex-specific genetic contribution in disorders of sexual development. The precise molecular mechanisms underlying these differences are currently not entirely known. An increased knowledge and understanding of the role of candidate genes will undeniably be of great aid in elucidating the molecular basis of sex-biased disorders and potentially allow for more sex-specific therapies.

The sex-specific interaction of the microbiome in neurodegenerative diseases

Several neurologic diseases exhibit different prevalence and severity in males and females, highlighting the importance of understanding the influence of biologic sex and gender. Beyond host-intrinsic differences in neurologic development and homeostasis, evidence is now emerging that the microbiota is an important environmental factor that may account for differences between men and women in neurologic disease. The gut microbiota is composed of trillions of bacteria, archaea, viruses, and fungi, that can confer benefits to the host or promote disease. There is bidirectional communication between the intestinal microbiota and the brain that is mediated via immunologic, endocrine, and neural signaling pathways. While there is substantial interindividual variation within the microbiota, differences between males and females can be detected. In animal models, sex-specific microbiota differences can affect susceptibility to chronic diseases. In this review, we discuss the ways in which neurologic diseases may be regulated by the microbiota in a sex-specific manner.

Hypogonadotrophic hypogonadism, delayed puberty and risk for neurodevelopmental disorders

Hypogonadotrophic hypogonadism (HH) is a rare disorder that manifests absent puberty and infertility. Genetic syndromes with hypogonadism, such as Klinefelter syndrome, are associated with an increased risk of neurodevelopmental disorders (NDDs). However, it is not clear whether patients with HH or transient delayed puberty in general, have an increased risk of NDDs. We performed a register-based study on a national cohort of 264 patients with HH and 7447 patients diagnosed with delayed puberty that was matched with 2640 and 74 470 controls, respectively. The outcome was defined as having any of the following NDD diagnoses: (i) autism spectrum disorder (ASD); (ii) attention deficit hyperactivity disorder (ADHD); or (iii) intellectual disability (ID). Additional sensitivity analyses were performed to control for different parental and birth variables, as well as diagnosed malformation syndromes and chromosomal anomalies (ie, Down's and Turner syndromes). Patients with HH had increased risk for being diagnosed with ASD (odds ratio [OR] = 5.7; 95% confidence interval [CI] = 2.6-12.6), ADHD (OR = 3.0; 95% CI = 1.8-5.1) and ID (OR = 18.0; 95% CI = 8.9-36.3) compared to controls. Patients with delayed puberty also had a significantly increased risk of being diagnosed with an NDD. These associations remained significant after adjustments. This is the first study to demonstrate a significant association between HH, delayed puberty and NDDs in a population-based cohort. Clinicians should be aware of the overlap between these disorders. Further studies should explore the mechanisms behind these associations.

Putative contributions of the sex chromosome proteins SOX3 and SRY to neurodevelopmental disorders

The male-biased prevalence of certain neurodevelopmental disorders and the sex-biased outcomes associated with stress exposure during gestation have been previously described. Here, we hypothesized that genes distinctively targeted by only one or both homologous proteins highly conserved across therian mammals, SOX3 and SRY, could induce sexual adaptive changes that result in a differential risk for neurodevelopmental disorders. ChIP-seq/chip data showed that SOX3/SRY gene targets were expressed in different brain cell types in mice. We used orthologous human genes in rodent genomes to extend the number of SOX3/SRY set (1,721). These genes were later found to be enriched in five modules of coexpressed genes during the early and mid-gestation periods (FDR < 0.05), independent of sexual hormones. Genes with differential expression (24, p < 0.0001) and methylation (40, p < 0.047) between sexes were overrepresented in this set. Exclusive SOX3 or SRY target genes were more associated with the late gestational and postnatal periods. Using autism as a model sex-biased disorder, the SOX3/SRY set was enriched in autism gene databases (FDR ≤ 0.05), and there were more de novo variations from the male autism spectrum disorder (ASD) samples under the SRY peaks compared to the random peaks (p < 0.024). The comparison of coexpressed networks of SOX3/SRY target genes between male autism and control samples revealed low preservation in gene modules related to stress response (99 genes) and neurogenesis (78 genes). This study provides evidence that while SOX3 is a regulatory mechanism for both sexes, the male-exclusive SRY also plays a role in gene regulation, suggesting a potential mechanism for sex bias in ASD.

Sex-specific neuroprotection by inhibition of the Y-chromosome gene, SRY, in experimental Parkinson's disease

Parkinson's disease (PD) is a debilitating neurodegenerative disorder caused by the loss of midbrain dopamine (DA) neurons. While the cause of DA cell loss in PD is unknown, male sex is a strong risk factor. Aside from the protective actions of sex hormones in females, emerging evidence suggests that sex-chromosome genes contribute to the male bias in PD. We previously showed that the Y-chromosome gene, SRY, directly regulates adult brain function in males independent of gonadal hormone influence. SRY protein colocalizes with DA neurons in the male substantia nigra, where it regulates DA biosynthesis and voluntary movement. Here we demonstrate that nigral SRY expression is highly and persistently up-regulated in animal and human cell culture models of PD. Remarkably, lowering nigral SRY expression with antisense oligonucleotides in male rats diminished motor deficits and nigral DA cell loss in 6-hydroxydopamine (6-OHDA)-induced and rotenone-induced rat models of PD. The protective effect of the SRY antisense oligonucleotides was associated with male-specific attenuation of DNA damage, mitochondrial degradation, and neuroinflammation in the toxin-induced rat models of PD. Moreover, reducing nigral SRY expression diminished or removed the male bias in nigrostriatal degeneration, mitochondrial degradation, DNA damage, and neuroinflammation in the 6-OHDA rat model of PD, suggesting that SRY directly contributes to the sex differences in PD. These findings demonstrate that SRY directs a previously unrecognized male-specific mechanism of DA cell death and suggests that suppressing nigral Sry synthesis represents a sex-specific strategy to slow or prevent DA cell loss in PD.

Evaluation of α-synuclein and apolipoprotein E as potential biomarkers in cerebrospinal fluid to monitor pharmacotherapeutic efficacy in dopamine dictated disease states of Parkinson's disease and schizophrenia

BACKGROUND AND OBJECTIVE

Dopamine plays an important role in the disease pathology of Parkinson's disease and schizophrenia. These two neuropsychiatric disorders represent disease end points of the dopaminergic spectrum where Parkinson's disease represents dopamine deficit and schizophrenia represents dopamine hyperactivity in the mid-brain. Therefore, current treatment strategies aim to restore normal dopamine levels. However, during treatment patients develop adverse effects due to overshooting of physiological levels of dopamine leading to psychosis in Parkinson's disease, and extrapyramidal symptoms in schizophrenia. Absence of any laboratory tests hampers modulation of pharmacotherapy. Apolipoprotein E and α-synuclein have an important role in the neuropathology of these two diseases. The objective of this study was to evaluate cerebrospinal fluid (CSF) concentrations of apolipoprotein E and α-synuclein in patients with these two diseases so that they may serve as biomarkers to monitor therapy in Parkinson's disease and schizophrenia.

METHODS

Drug-naïve Parkinson's disease patients and Parkinson's disease patients treated with dopaminergic therapy, neurological controls, schizophrenic patients treated with antidopaminergic therapy, and drug-naïve schizophrenic patients were recruited for the study and CSF was collected. Enzyme-linked immunosorbent assays were carried out to estimate the concentrations of apolipoprotein E and α-synuclein. Pathway analysis was done to establish a possible role of these two proteins in various pathways in these two dopamine dictated diseases.

RESULTS

Apolipoprotein E and α-synuclein CSF concentrations have an inverse correlation along the entire dopaminergic clinical spectrum. Pathway analysis convincingly establishes a plausible hypothesis for their co-regulation in the pathogenesis of Parkinson's disease and schizophrenia. Each protein by itself or as a combination has encouraging sensitivity and specificity values of more than 55%.

CONCLUSION

The dynamic variation of these two proteins along the spectrum is ideal for them to be pursued as pharmacotherapeutic biomarkers in CSF to monitor pharmacological efficacy in Parkinson's disease and schizophrenia.

Men and women respond differently to antipsychotic drugs

BACKGROUND

Because women are often perceived as having better outcomes than men in psychotic illnesses such as schizophrenia - women are less often in hospital, have a lower suicide rate, are less often involved with the law, enjoy better relationships with family and friends - the question arises as to whether or not this apparent advantage is attributable to a gender difference in antipsychotic response.

OBJECTIVE

The aim of this paper is to critically review the quantitative and qualitative literature on gender difference in antipsychotic response sourced mainly from medical databases of the last ten years.

FINDINGS

There are theoretical reasons why women's effective doses of antipsychotics might need to be lower than guidelines recommend for men, especially as regards olanzapine and clozapine, but, because there are so many variables that impinge on antipsychotic response, it is difficult to provide definitive guidance. What is evident is that some antipsychotic side effects, weight gain for instance, are more worrisome for women than for men. It is also evident that, after menopause, women need an increase in their antipsychotic dose; other reproductive stages in women's lives require special prescribing considerations as well.

CONCLUSION

There is a science, and an art, to prescribing antipsychotics, which needs to take gender into account. This article is part of the issue entitled 'Special Issue on Antipsychotics'.

2D-DIGE as a strategy to identify serum protein biomarkers to monitor pharmacological efficacy in dopamine-dictated states of Parkinson's disease and schizophrenia

OBJECTIVES

Parkinson's disease and schizophrenia are clinical scenarios that occur due to dopaminergic deficit and hyperactivity in the midbrain, respectively. Current pharmacological interventions for these two diseases therefore aim to restore normal dopamine levels in the midbrain. But during therapy, there is a overshooting of dopamine concentrations that result in hallucinations in Parkinson's disease patients and extra-pyramidal symptoms in schizophrenic patients. This causes a lot of inconvenience to the patents and the clinicians. There are no tests currently available to monitor drug efficacy in these two neuropsychiatric diseases.

MATERIALS AND METHODS

Parkinson's disease and schizophrenic naïve patients were recruited. Serum proteins isolated from these two clinical phenotypes were labeled with fluorescent cyanine dyes and analyzed by two-dimensional difference in gel electrophoresis proteomic experiment. Differentially expressed spots that had consistent expression pattern across five sets of biological replicate gels were trypsin digested and subjected to mass spectrometric analysis for protein identification. Validation experiments were done for the identified proteins using antibody-based assay on a patient cohort that included naïve, treated, and those who had side effects.

RESULTS

Serum α- and β-globin chains were identified as differentially expressed proteins having threefold higher expressions in Parkinson's patients as compared to schizophrenia. Interestingly, concentrations of these two proteins had an inverse correlation across clinical phenotypes in the dopaminergic spectrum. RBC contamination as a source for these proteins was ruled out.

CONCLUSION

There is a clear association of free serum globin with dopaminergic clinical states. This lays a platform for protein biomarker-based monitoring of pharmacological efficacy in Parkinson's disease and schizophrenia.

Mutation in the vasopressin gene eliminates the sex difference in social reinforcement in adolescent rats

The neuropeptide, arginine vasopressin (AVP), is thought to contribute to sex differences in normative and pathological social development by regulating social motivation. Recent studies using Brattleboro rats that have a mutation in the Avp gene, however, have suggested that AVP impacts adolescent social behaviors of males and females in a similar manner through actions on behavioral state (i.e., arousal). In the present study, we made use of a recently developed operant conditioning paradigm to test whether the chronic, lifelong AVP deficiency caused by the Brattleboro mutation impacts the reinforcement value of social stimuli during adolescence. Operant responding for access to a familiar conspecific was assessed in male and female adolescent wild type (WT; normal AVP), heterozygous Brattleboro (HET), and homozygous Brattleboro (HOM) rats. Following the social reinforcement test, rats were tested in the same operant paradigm except that the social reinforcer was replaced with a light reinforcer to determine whether effects of the Brattleboro mutation were specific to social stimuli or a general characteristic of operant conditioning. WT males directed a greater proportion of their responding toward the social and light stimuli than WT females; only males exhibited a preference for these reinforcers over unreinforced ports. The sex difference in social reinforcement was absent in HOM rats, whereas the sex difference in light reinforcement was present in all genotypes. These data indicate that adolescent males are more sensitive to the reinforcing properties of social and light stimuli, and that the sex difference in social, but not light, reinforcement depends upon normal levels of AVP. These findings support the hypothesis that AVP plays a critical role in sex differences in social development by acting on factors that influence social motivation.

ADGRL3 rs6551665 as a Common Vulnerability Factor Underlying Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder

Neurodevelopmental disorders are prevalent, frequently occur in comorbidity and share substantial genetic correlation. Previous evidence has suggested a role for the ADGRL3 gene in Attention-Deficit/Hyperactivity Disorder (ADHD) susceptibility in several samples. Considering ADGRL3 functionality in central nervous system development and its previous association with neurodevelopmental disorders, we aimed to assess ADGRL3 influence in early-onset ADHD (before 7 years of age) and Autism Spectrum Disorder (ASD). The sample comprises 187 men diagnosed with early-onset ADHD, 135 boys diagnosed with ASD and 468 male blood donors. We tested the association of an ADGRL3 variant (rs6551665) with both early-onset ADHD and ASD susceptibility. We observed significant associations between ADGRL3-rs6551665 on ADHD and ASD susceptibilities; we found that G-carriers were at increased risk of ADHD and ASD, in accordance with previous studies. The overall evidence from the literature, corroborated by our results, suggests that ADGRL3 might be involved in brain development, and genetic modifications related to it might be part of a shared vulnerability factor associated with the underlying neurobiology of neurodevelopmental disorders such as ADHD and ASD.

Cerebrospinal Fluid Proteomics For Identification Of α2-Macroglobulin As A Potential Biomarker To Monitor Pharmacological Therapeutic Efficacy In Dopamine Dictated Disease States Of Parkinson's Disease And Schizophrenia

AIM

Parkinson's disease and schizophrenia are clinical end points of dopaminergic deficit and excess, respectively, in the mid-brain. In accordance, current pharmacological interventions aim to restore normal dopamine levels, the overshooting of which culminates in adverse effects which results in psychotic symptoms in Parkinson's disease and extra-pyramidal symptoms in schizophrenia. Currently, there are no laboratory assays to assist treatment decisions or help foresee these drug side-effect outcomes. Therefore, the aim was to discover a protein biomarker that had a varying linear expression across the clinical dopaminergic spectrum.

MATERIALS AND METHODS

iTRAQ-based proteomic experiments along with mass spectrometric analysis was used for comparative proteomics using cerebrospinal fluid (CSF). CSF fluid was collected from 36 patients with Parkinson's disease, 15 patients with urological diseases that served as neurological controls, and seven schizophrenic patients with hallucinations. Validation included ELISA and pathway analysis to highlight the varying expression and provide plausible molecular pathways for differentially expressed proteins in the three clinical phenotypes.

RESULTS

Protein profiles were delineated in CSF from Parkinson's disease patients, neurological control and schizophrenia, respectively. Ten of the proteins that were identified had a linear relationship across the dopaminergic spectrum. α-2-Macroglobulin showed to be having high statistical significance on inter-group comparison on validation studies using ELISA.

CONCLUSIONS

Non-gel-based proteomic experiments are an ideal platform to discover potential biomarkers that can be used to monitor pharmaco-therapeutic efficacy in dopamine-dictated clinical scenarios. α-2 Macroglobulin is a potential biomarker to monitor pharmacological therapy in Parkinson's disease and schizophrenia.

Assessing Positive Child Health among Individuals Born Extremely Preterm

OBJECTIVE

To assess the development of a Positive Child Health Index (PCHI) based on 11 adverse outcomes and evaluate the association of PCHI with quality of life (QoL) scores in a preterm cohort.

STUDY DESIGN

A total of 889 children enrolled in the Extremely Low Gestational Age Newborn (ELGAN) study in 2002-2004 were followed up at 10 years of age. A parent/caregiver completed questionnaires for child QoL, asthma, visual or hearing impairment, gross motor function impairment, epilepsy, attention deficit/hyperactivity disorder, anxiety, and depression. The child was assessed for cognitive impairment, autism, and obesity. PCHI scores were computed and linear regression models were used to evaluate the relationship between QoL categories (psychosocial, physical, emotional, social, school, and total) and the PCHI (dichotomized and coded as a multilevel categorical predictor) and to assess sex differences.

RESULTS

Among ELGAN children, higher PCHI scores were associated with higher reported QoL scores for all QoL categories. Children with no disorders and a PCHI of 100% had Pediatric Quality of Life Inventory total scores that were 11 points higher than children with 1 or more adverse outcomes (PCHI of <100%). Boys had lower QoL scores for the total, psychosocial, social, and school categories.

CONCLUSIONS

Positive child health assessed using a quantitative PCHI was associated with QoL across the ELGAN cohort at school age. In the current study, the PCHI encompassed 11 outcomes assessed in ELGANs. Future research could include an enhanced panel of child health outcomes to support the use of PCHI as an indicator of positive child health.

Evaluation of Serum Apolipoprotein E as a Potential Biomarker for Pharmacological Therapeutic Efficacy Monitoring in Dopamine Dictated Disease Spectrum of Schizophrenia and Parkinson's disease: A Preliminary Study

AIM OF THE STUDY

Parkinson's disease and schizophrenia are disease end points of dopaminergic deficit and hyperactivity, respectively, in the mid brain. Accordingly, current medications aim to restore normal dopamine levels, overshooting of which results in adverse effects of psychosis and extra-pyramidal symptoms, respectively. There are currently no available laboratory tests to guide treatment decisions or help predict adverse side effects of the drugs. The aim was to therefore explore the possibility of using apolipoprotein E as a biomarker to monitor pharmacological intervention in dopamine dictated states of Parkinson's disease and schizophrenia for optimum therapy.

METHODS

Naïve and treated, Parkinson's disease and schizophrenic patients were recruited from neurology and psychiatry clinics. Serum of healthy volunteers was collected as controls. Serum concentrations of apolipoprotein E was estimated by enzyme-linked immunosorbent assay (ELISA). Pathway analysis was carried out to delineate the interactions of apolipoprotein E in Parkinson's disease and schizophrenia.

RESULTS

Apolipoprotein E levels are higher in Parkinson's disease patients as compared with schizophrenic samples (P < .05). Also, post-treatment apolipoprotein E levels in both disease states were at par with levels seen in healthy controls. The interactions of apolipoprotein E validate the results and place the differential expression of the protein in Parkinson's disease and schizophrenia in the right perspective.

CONCLUSION

Apolipoprotein E concentration across the dopaminergic spectrum suggests that it can be pursued not only as a potential biomarker in schizophrenia and Parkinson's disease, but can also be an effective tool for clinicians to determine efficacy of drug-based therapy.

Genes and Pathways Regulated by Androgens in Human Neural Cells, Potential Candidates for the Male Excess in Autism Spectrum Disorder

BACKGROUND

Prenatal exposure to androgens during brain development in male individuals may participate to increase their susceptibility to develop neurodevelopmental disorders such as autism spectrum disorder (ASD) and intellectual disability. However, little is known about the action of androgens in human neural cells.

METHODS

We used human neural stem cells differentiated from embryonic stem cells to investigate targets of androgens.

RESULTS

RNA sequencing revealed that treatment with dihydrotestosterone (DHT) leads to subtle but significant changes in the expression of about 200 genes, encoding proteins of extracellular matrix or involved in signal transduction of growth factors (e.g., insulin/insulin growth factor 1). We showed that the most differentially expressed genes (DEGs), RGCC, RNF144B, NRCAM, TRIM22, FAM107A, IGFBP5, and LAMA2, are reproducibly regulated by different androgens in different genetic backgrounds. We showed, by overexpressing the androgen receptor in neuroblastoma cells SH-SY5Y or knocking it down in human neural stem cells, that this regulation involves the androgen receptor. A chromatin immunoprecipitation combined with direct sequencing analysis identified androgen receptor-bound sequences in nearly half of the DHT-DEGs and in numerous other genes. DHT-DEGs appear enriched in genes involved in ASD (ASXL3, NLGN4X, etc.), associated with ASD (NRCAM), or differentially expressed in patients with ASD (FAM107A, IGFBP5). Androgens increase human neural stem cell proliferation and survival in nutrient-deprived culture conditions, with no detectable effect on regulation of neurite outgrowth.

CONCLUSIONS

We characterized androgen action in neural progenitor cells, identifying DHT-DEGs that appear to be enriched in genes related to ASD. We also showed that androgens increase proliferation of neuronal precursors and protect them from death during their differentiation in nutrient-deprived conditions.

Sex: A Significant Risk Factor for Neurodevelopmental and Neurodegenerative Disorders

Males and females sometimes significantly differ in their propensity to develop neurological disorders. Females suffer more from mood disorders such as depression and anxiety, whereas males are more susceptible to deficits in the dopamine system including Parkinson's disease (PD), attention-deficit hyperactivity disorder (ADHD) and autism. Despite this, biological sex is rarely considered when making treatment decisions in neurological disorders. A better understanding of the molecular mechanism(s) underlying sex differences in the healthy and diseased brain will help to devise diagnostic and therapeutic strategies optimal for each sex. Thus, the aim of this review is to discuss the available evidence on sex differences in neuropsychiatric and neurodegenerative disorders regarding prevalence, progression, symptoms and response to therapy. We also discuss the sex-related factors such as gonadal sex hormones and sex chromosome genes and how these might help to explain some of the clinically observed sex differences in these disorders. In particular, we highlight the emerging role of the Y-chromosome gene, SRY, in the male brain and its potential role as a male-specific risk factor for disorders such as PD, autism, and ADHD in many individuals.

Metabolic syndrome and risk of Parkinson disease: A nationwide cohort study

BACKGROUND

The association of metabolic syndrome (MetS) with the development of Parkinson disease (PD) is currently unclear. We sought to determine whether MetS and its components are associated with the risk of incident PD using large-scale cohort data for the whole South Korean population.

METHODS AND FINDINGS

Health checkup data of 17,163,560 individuals aged ≥40 years provided by the National Health Insurance Service (NHIS) of South Korea between January 1, 2009, and December 31, 2012, were included, and participants were followed up until December 31, 2015. The mean follow-up duration was 5.3 years. The hazard ratio (HR) and 95% confidence interval (CI) of PD were estimated using a Cox proportional hazards model adjusted for potential confounders. We identified 44,205 incident PD cases during follow-up. Individuals with MetS (n = 5,848,508) showed an increased risk of PD development compared with individuals without MetS (n = 11,315,052), even after adjusting for potential confounders including age, sex, smoking, alcohol consumption, physical activity, income, body mass index, estimated glomerular filtration rate, and history of stroke (model 3; HR, 95% CI: 1.24, 1.21-1.27). Each MetS component was positively associated with PD risk (HR, 95% CI: 1.13, 1.10-1.16 for abdominal obesity; 1.13, 1.10-1.15 for hypertriglyceridemia; 1.23, 1.20-1.25 for low high-density lipoprotein cholesterol; 1.05, 1.03-1.08 for high blood pressure; 1.21, 1.18-1.23 for hyperglycemia). PD incidence positively correlated with the number of MetS components (log-rank p < 0.001), and we observed a gradual increase in the HR for incident PD with increasing number of components (p < 0.001). A significant interaction between age and MetS on the risk of incident PD was observed (p for interaction < 0.001), and people aged ≥65 years old with MetS showed the highest HR of incident PD of all subgroups compared to those <65 years old without MetS (reference subgroup). Limitations of this study include the possibilities of misdiagnosis of PD and reverse causality.

CONCLUSIONS

Our population-based large-scale cohort study suggests that MetS and its components may be risk factors of PD development.

Evidence for sex difference in the CSF/plasma albumin ratio in ~20 000 patients and 335 healthy volunteers

Given sex-related differences in brain disorders, it is of interest to study if there is a sex difference in the permeability of the blood-cerebrospinal fluid barrier (BCSFB) and the blood-brain barrier (BBB). The CSF/serum albumin ratio (Q_Alb ) is a standardized biomarker that evaluates the function of these barriers. In previous studies, contradictory results have been reported with respect to sex difference using this quotient, possibly because of small population sizes and heterogeneity with respect to ages. Q_Alb measurements in more than 20 000 patients between 1 and 90 years visiting our hospitals revealed a significant sex difference in all age groups also when excluding patients with pathologically high CSF albumin > 400 mg/L. Similar pattern was found in 335 healthy volunteers in similar age intervals. Although also other factors are likely important, our observation is consistent with lower integrity of the brain barriers in males. If the difference in Q_Alb is caused mainly by a difference in barrier function, this may require different drug doses and strategies for efficient central nervous system (CNS) delivery in males and females, as well as it may indicate differences in brain metabolism. Moreover, our study emphasizes that different reference values should be used both for different ages and sexes.

Sex differences in Parkinson's disease: Features on clinical symptoms, treatment outcome, sexual hormones and genetics

Parkinson's disease (PD) is the second most frequent age-related neurodegenerative disorder. Sex is an important factor in the development of PD, as reflected by the fact that it is more common in men than in women by an approximate ratio of 2:1. Our hypothesis is that differences in PD among men and women are highly determined by sex-dependent differences in the nigrostriatal dopaminergic system, which arise from environmental, hormonal and genetic influences. Sex hormones, specifically estrogens, influence PD pathogenesis and might play an important role in PD differences between men and women. The objective of this review was to discuss the PD physiopathology and point out sex differences in nigrostriatal degeneration, symptoms, genetics, responsiveness to treatments and biochemical and molecular mechanisms among patients suffering from this disease. Finally, we discuss the role estrogens may have on PD sex differences.

A Genetic Investigation of Sex Bias in the Prevalence of Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) shows substantial heritability and is two to seven times more common in male individuals than in female individuals. We examined two putative genetic mechanisms underlying this sex bias: sex-specific heterogeneity and higher burden of risk in female cases.

METHODS

We analyzed genome-wide autosomal common variants from the Psychiatric Genomics Consortium and iPSYCH Project (n = 20,183 cases, n = 35,191 controls) and Swedish population register data (n = 77,905 cases, n = 1,874,637 population controls).

RESULTS

Genetic correlation analyses using two methods suggested near complete sharing of common variant effects across sexes, with rg estimates close to 1. Analyses of population data, however, indicated that female individuals with ADHD may be at especially high risk for certain comorbid developmental conditions (i.e., autism spectrum disorder and congenital malformations), potentially indicating some clinical and etiological heterogeneity. Polygenic risk score analysis did not support a higher burden of ADHD common risk variants in female cases (odds ratio [confidence interval] = 1.02 [0.98-1.06], p = .28). In contrast, epidemiological sibling analyses revealed that the siblings of female individuals with ADHD are at higher familial risk for ADHD than the siblings of affected male individuals (odds ratio [confidence interval] = 1.14 [1.11-1.18], p = 1.5E-15).

CONCLUSIONS

Overall, this study supports a greater familial burden of risk in female individuals with ADHD and some clinical and etiological heterogeneity, based on epidemiological analyses. However, molecular genetic analyses suggest that autosomal common variants largely do not explain the sex bias in ADHD prevalence.

Sex-Specific Transcriptome Differences in Substantia Nigra Tissue: A Meta-Analysis of Parkinson's Disease Data

Parkinson’s disease (PD) is one of the most common progressive neurodegenerative diseases. Clinical and epidemiological studies indicate that sex differences, as well as genetic components and ageing, can influence the prevalence, age at onset and symptomatology of PD. This study undertook a systematic meta-analysis of substantia nigra microarray data using the Transcriptome Mapper (TRAM) software to integrate and normalize a total of 10 suitable datasets from multiple sources. Four different analyses were performed according to default parameters, to better define the segments differentially expressed between PD patients and healthy controls, when comparing men and women data sets. The results suggest a possible regulation of specific sex-biased systems in PD susceptibility. TRAM software allowed us to highlight the different activation of some genomic regions and loci involved in molecular pathways related to neurodegeneration and neuroinflammatory mechanisms.

Sexual Dimorphism and Sex Differences in Caenorhabditis elegans Neuronal Development and Behavior

As fundamental features of nearly all animal species, sexual dimorphisms and sex differences have particular relevance for the development and function of the nervous system. The unique advantages of the nematode Caenorhabditis elegans have allowed the neurobiology of sex to be studied at unprecedented scale, linking ultrastructure, molecular genetics, cell biology, development, neural circuit function, and behavior. Sex differences in the C. elegans nervous system encompass prominent anatomical dimorphisms as well as differences in physiology and connectivity. The influence of sex on behavior is just as diverse, with biological sex programming innate sex-specific behaviors and modifying many other aspects of neural circuit function. The study of these differences has provided important insights into mechanisms of neurogenesis, cell fate specification, and differentiation; synaptogenesis and connectivity; principles of circuit function, plasticity, and behavior; social communication; and many other areas of modern neurobiology.

Loss of chromosome Y in blood, but not in brain, of suicide completers

Men have a higher rate of completed suicide than women, which suggests that sex chromosome abnormalities may be related to the pathophysiology of suicide. Recent studies have found an aberrant loss of chromosome Y (LOY) in various diseases; however, no study has investigated whether there is an association between LOY and suicide. The purpose of this study was to determine whether LOY occurs in men who completed suicide. Our study consisted of 286 male Japanese subjects comprised of 140 suicide completers without severe physical illness (130 post-mortem samples of peripheral blood and 10 brains) and 146 age-matched control subjects (130 peripheral blood samples from healthy individuals and 16 post-mortem brains). LOY was measured as the chromosome Y/chromosome X ratio of the fluorescent signal of co-amplified short sequences from the Y-X homologous amelogenin genes (AMELY and AMELX). Regression analyses showed that LOY in the blood of suicide completers was significantly more frequent than that found in controls (odds ratio = 3.50, 95% confidence interval = 1.21–10.10), but not in the dorsolateral prefrontal cortex (DLPFC) region of brain. Normal age-dependent LOY in blood was found in healthy controls (r = -0.353, p < 0.001), which was not seen in suicide completers (r = -0.119, p = 0.177). DLPFC tissue had age-dependent LOY (B = -0.002, p = 0.015), which was independent of phenotype. To our knowledge, this is the first study demonstrating that LOY in blood is associated with suicide completion. In addition, our findings are the first to also indicate that age-dependent LOY may occur not only in blood, but also in specific brain regions.

Genetic loss of diazepam binding inhibitor in mice impairs social interest

Neuropsychiatric disorders in which reduced social interest is a common symptom, such as autism, depression, and anxiety, are frequently associated with genetic mutations affecting γ-aminobutyric acid (GABA)ergic transmission. Benzodiazepine treatment, acting via GABA type-A receptors, improves social interaction in male mouse models with autism-like features. The protein diazepam binding inhibitor (DBI) can act as an endogenous benzodiazepine, but a role for DBI in social behavior has not been described. Here, we investigated the role of DBI in the social interest and recognition behavior of mice. The responses of DBI wild-type and knockout male and female mice to ovariectomized female wild-type mice (a neutral social stimulus) were evaluated in a habituation/dishabituation task. Both male and female knockout mice exhibited reduced social interest, and DBI knockout mice lacked the sex difference in social interest levels observed in wild-type mice, in which males showed higher social interest levels than females. The ability to discriminate between familiar and novel stimulus mice (social recognition) was not impaired in DBI-deficient mice of either sex. DBI knockouts could learn a rotarod motor task, and could discriminate between social and nonsocial odors. Both sexes of DBI knockout mice showed increased repetitive grooming behavior, but not in a manner that would account for the decrease in social investigation time. Genetic loss of DBI did not alter seminal vesicle weight, indicating that the social interest phenotype of males lacking DBI is not due to reduced circulating testosterone. Together, these studies show a novel role of DBI in driving social interest and motivation.

Healthy minds from 0-100 years: Optimising the use of European brain imaging cohorts ("Lifebrain")

The main objective of "Lifebrain" is to identify the determinants of brain, cognitive and mental (BCM) health at different stages of life. By integrating, harmonising and enriching major European neuroimaging studies across the life span, we will merge fine-grained BCM health measures of more than 5,000 individuals. Longitudinal brain imaging, genetic and health data are available for a major part, as well as cognitive and mental health measures for the broader cohorts, exceeding 27,000 examinations in total. By linking these data to other databases and biobanks, including birth registries, national and regional archives, and by enriching them with a new online data collection and novel measures, we will address the risk factors and protective factors of BCM health. We will identify pathways through which risk and protective factors work and their moderators. Exploiting existing European infrastructures and initiatives, we hope to make major conceptual, methodological and analytical contributions towards large integrative cohorts and their efficient exploitation. We will thus provide novel information on BCM health maintenance, as well as the onset and course of BCM disorders. This will lay a foundation for earlier diagnosis of brain disorders, aberrant development and decline of BCM health, and translate into future preventive and therapeutic strategies. Aiming to improve clinical practice and public health we will work with stakeholders and health authorities, and thus provide the evidence base for prevention and intervention.

Pregnancy at Advanced Maternal Age Affects Behavior and Hippocampal Gene Expression in Mouse Offspring

There is growing evidence that advanced maternal age is a risk factor for neurological and neuropsychiatric disorders in offspring. However, it remains unclear whether the altered brain programming induced by advanced maternal age is mediated by pre- or postnatal factors. Here, a mouse model was used to investigate whether pregnancy at advanced age may provoke behavioral and brain gene expression changes in offspring. Swiss Albino mice conceived by 3-month-old males and either 15-18-month-old (n = 11) or 3-month-old control females (n = 5), were delivered by cesarean section, fostered after birth by 3-month-old dams and subjected to a battery of behavioral tests. Furthermore, genome-wide mRNA expression was analyzed in the hippocampi of 4-month-old males offspring using microarrays. Offspring conceived by old mothers exhibited increased ultrasound vocalization activity during separation from the foster mother, increased anxiety-like behaviors in adult life, and altered patterns of hippocampal gene expression, compared to controls. These effects were not reversed by the postnatal maternal care provided by the young foster mothers, suggesting that the altered brain programming is already established at birth, consistent with prenatal effects related to maternal aging.

Chromosome-Centric Human Proteome Project Allies with Developmental Biology: A Case Study of the Role of Y Chromosome Genes in Organ Development

One of the main goals of Chromosome-Centric Human Proteome Project is to identify protein evidence for missing proteins (MPs). Here, we present a case study of the role of Y chromosome genes in organ development and how to overcome the challenges facing MPs identification by employing human pluripotent stem cell differentiation into cells of different organs yielding unprecedented biological insight into adult silenced proteins. Y chromosome is a male-specific sex chromosome which escapes meiotic recombination. From an evolutionary perspective, Y chromosome has preserved 3% of ancestral genes compared to 98% preservation of the X chromosome based on Ohno's law. Male specific region of Y chromosome (MSY) contains genes that contribute to central dogma and govern the expression of various targets throughout the genome. One of the most well-known functions of MSY genes is to decide the male-specific characteristics including sex, testis formation, and spermatogenesis, which are majorly formed by ampliconic gene families. Beyond its role in sex-specific gonad development, MSY genes in coexpression with their X counterparts, as single copy and broadly expressed genes, inhibit haplolethality and play a key role in embryogenesis. The role of X-Y related gene mutations in the development of hereditary syndromes suggests an essential contribution of sex chromosome genes to development. MSY genes, solely and independent of their X counterparts and/or in association with sex hormones, have a considerable impact on organ development. In this Review, we present major recent findings on the contribution of MSY genes to gonad formation, spermatogenesis, and the brain, heart, and kidney development and discuss how Y chromosome proteome project may exploit developmental biology to find missing proteins.

Of sex and determination: marking 25 years of Randy, the sex-reversed mouse

On Thursday 9 May 1991, the world awoke to front-page news of a breakthrough in biological research. From Washington to Wollongong, newspapers, radio and TV were abuzz with the story of a transgenic mouse in London called Randy. Why was this mouse so special? The mouse in question was a chromosomal female (XX) made male by the presence of a transgene containing the Y chromosome gene Sry This sex-reversal provided clear experimental proof that Sry was the elusive mammalian sex-determining gene. Twenty-five years on, we reflect on what this discovery meant for our understanding of how males and females arise and what remains to be understood.

Aberrant activation of the human sex-determining gene in early embryonic development results in postnatal growth retardation and lethality in mice

Sexual dimorphisms are prevalent in development, physiology and diseases in humans. Currently, the contributions of the genes on the male-specific region of the Y chromosome (MSY) in these processes are uncertain. Using a transgene activation system, the human sex-determining gene hSRY is activated in the single-cell embryos of the mouse. Pups with hSRY activated (hSRY^ON) are born of similar sizes as those of non-activated controls. However, they retard significantly in postnatal growth and development and all die of multi-organ failure before two weeks of age. Pathological and molecular analyses indicate that hSRY^ON pups lack innate suckling activities, and develop fatty liver disease, arrested alveologenesis in the lung, impaired neurogenesis in the brain and occasional myocardial fibrosis and minimized thymus development. Transcriptome analysis shows that, in addition to those unique to the respective organs, various cell growth and survival pathways and functions are differentially affected in the transgenic mice. These observations suggest that ectopic activation of a Y-located SRY gene could exert male-specific effects in development and physiology of multiple organs, thereby contributing to sexual dimorphisms in normal biological functions and disease processes in affected individuals.

Sex Hormones and Sex Chromosomes Cause Sex Differences in the Development of Cardiovascular Diseases

This review summarizes recent evidence concerning hormonal and sex chromosome effects in obesity, atherosclerosis, aneurysms, ischemia/reperfusion injury, and hypertension. Cardiovascular diseases occur and progress differently in the 2 sexes, because biological factors differing between the sexes have sex-specific protective and harmful effects. By comparing the 2 sexes directly, and breaking down sex into its component parts, one can discover sex-biasing protective mechanisms that might be targeted in the clinic. Gonadal hormones, especially estrogens and androgens, have long been found to account for some sex differences in cardiovascular diseases, and molecular mechanisms mediating these effects have recently been elucidated. More recently, the inherent sexual inequalities in effects of sex chromosome genes have also been implicated as contributors in animal models of cardiovascular diseases, especially a deleterious effect of the second X chromosome found in females but not in males. Hormonal and sex chromosome mechanisms interact in the sex-specific control of certain diseases, sometimes by opposing the action of the other.

Genes, Gender, Environment, and Novel Functions of Estrogen Receptor Beta in the Susceptibility to Neurodevelopmental Disorders

Many neurological disorders affect men and women differently regarding prevalence, progression, and severity. It is clear that many of these disorders may originate from defective signaling during fetal or perinatal brain development, which may affect males and females differently. Such sex-specific differences may originate from chromosomal or sex-hormone specific effects. This short review will focus on the estrogen receptor beta (ERβ) signaling during perinatal brain development and put it in the context of sex-specific differences in neurodevelopmental disorders. We will discuss ERβ’s recent discovery in directing DNA de-methylation to specific sites, of which one such site may bear consequences for the susceptibility to the neurological reading disorder dyslexia. We will also discuss how dysregulations in sex-hormone signaling, like those evoked by endocrine disruptive chemicals, may affect this and other neurodevelopmental disorders in a sex-specific manner through ERβ.

Gene and environment interaction: Is the differential susceptibility hypothesis relevant for obesity?

The differential susceptibility model states that a given genetic variant is associated with an increased risk of pathology in negative environments but greater than average resilience in enriched ones. While this theory was first implemented in psychiatric-genetic research, it may also help us to unravel the complex ways that genes and environments interact to influence feeding behavior and obesity. We reviewed evidence on gene vs. environment interactions that influence obesity development, aiming to support the applicability of the differential susceptibility model for this condition, and propose that various environmental "layers" relevant for human development should be considered when bearing the differential susceptibility model in mind. Mother-child relationship, socioeconomic status and individual's response are important modifiers of BMI and food intake when interacting with gene variants, "for better and for worse". While only a few studies to date have investigated obesity outcomes using this approach, we propose that the differential susceptibility hypothesis is in fact highly applicable to the study of genetic and environmental influences on feeding behavior and obesity risk.

Girls and Boys Born before 28 Weeks Gestation: Risks of Cognitive, Behavioral, and Neurologic Outcomes at Age 10 Years

OBJECTIVES

To compare the prevalence of cognitive, neurologic, and behavioral outcomes at 10 years of age in 428 girls and 446 boys who were born extremely preterm.

STUDY DESIGN

A total of 889 of 966 eligible children previously enrolled in the multicenter Extremely Low Gestational Age Newborns Study from 2002-2004 were evaluated at 10 years of age. Children underwent a neuropsychological battery and testing for autism spectrum disorder (ASD), and parents reported on their child's behavior, development, and seizures.

RESULTS

Of the children, 28% of boys and 21% of girls exhibited moderate to severe impairment on summary measures of cognitive abilities. Boys had a higher prevalence of impairment than girls in nearly all measures of cognition, were more than twice as likely to have microcephaly (15% in boys, 8% in girls), and require more often assistive devices to ambulate (6% in boys, 4% in girls). In contrast, boys and girls had comparable risk for a history of seizure (identified in 10% of the cohort) or epilepsy (identified in 7% of the cohort). The boy-to-girl ratio of ASD (9% in boys, 5% in girls) was lower than expected compared with the overall US autism population.

CONCLUSIONS

In this contemporary cohort of children born extremely premature and evaluated at school age, boys had higher prevalence of cognitive, neurologic, and behavioral deficits than girls. The ratio of boys to girls among those with ASD deserves further study as does the perinatal environmental-genetic interactions that might contribute to male preponderance of deficits in this high-risk sample.

The number of Purkinje neurons and their topology in the cerebellar vermis of normal and reln haplodeficient mouse

The Reeler heterozygous mice (reln(+/-)) are haplodeficient in the gene (reln) encoding for the reelin glycoprotein (RELN) and display reductions in brain/peripheral RELN similar to autistic or schizophrenic patients. Cytoarchitectonic alterations of the reln(+/-) brain may be subtle, and are difficult to demonstrate by current histological approaches. We analyzed the number and topological organization of the Purkinje neurons (PNs) in five vermal lobules - central (II-III), culmen (IV-V), tuber (VIIb), uvula (IX), and nodulus (X) - that process different types of afferent functional inputs in reln(+/+) and reln(+/-) adult mice (P60) of both sexes (n=24). Animals were crossed with L7GFP mice so that the GFP-tagged PNs could be directly identified in cryosections. Digital images from these sections were processed with different open source software for quantitative topological and statistical analyses. Diversity indices calculated were: maximum caliper, density, area of soma, dispersion along the XZ axis, and dispersion along the YZ axis. We demonstrate: i. reduction in density of PNs in reln(+/-) males (14.37%) and reln(+/-) females (17.73%) compared to reln(+/+) males; ii. that reln(+/-) males have larger PNs than other genotypes, and females (irrespective of the reln genetic background) have smaller PNs than reln(+/+) males; iii. PNs are more chaotically arranged along the YZ axis in reln(+/-) males than in reln(+/+) males and, except in central lobulus, reln(+/-) females. Therefore, image processing and statistics reveal previously unforeseen gender and genotype-related structural differences in cerebellum that may be clues for the definition of novel biomarkers in human psychiatric disorders.

Decoding the non-coding genome: elucidating genetic risk outside the coding genome

Current evidence emerging from genome-wide association studies indicates that the genetic underpinnings of complex traits are likely attributable to genetic variation that changes gene expression, rather than (or in combination with) variation that changes protein-coding sequences. This is particularly compelling with respect to psychiatric disorders, as genetic changes in regulatory regions may result in differential transcriptional responses to developmental cues and environmental/psychosocial stressors. Until recently, however, the link between transcriptional regulation and psychiatric genetic risk has been understudied. Multiple obstacles have contributed to the paucity of research in this area, including challenges in identifying the positions of remote (distal from the promoter) regulatory elements (e.g. enhancers) and their target genes and the underrepresentation of neural cell types and brain tissues in epigenome projects - the availability of high-quality brain tissues for epigenetic and transcriptome profiling, particularly for the adolescent and developing brain, has been limited. Further challenges have arisen in the prediction and testing of the functional impact of DNA variation with respect to multiple aspects of transcriptional control, including regulatory-element interaction (e.g. between enhancers and promoters), transcription factor binding and DNA methylation. Further, the brain has uncommon DNA-methylation marks with unique genomic distributions not found in other tissues - current evidence suggests the involvement of non-CG methylation and 5-hydroxymethylation in neurodevelopmental processes but much remains unknown. We review here knowledge gaps as well as both technological and resource obstacles that will need to be overcome in order to elucidate the involvement of brain-relevant gene-regulatory variants in genetic risk for psychiatric disorders.

Perinatal exposure to endocrine disruptors: sex, timing and behavioral endpoints

Of the approximately 85,000 chemicals in use, 1000 have been identified as having the ability to disrupt normal endocrine function. Exposure to endocrine disrupting chemicals (EDCs) during critical period in brain differentiation (prenatal and neonatal life) via the mother can alter the course of the development of sexually dimorphic behaviors. Bisphenol A (BPA) is a very high volume chemical used in plastic, resins and other products, and virtually everyone examined has detectable BPA. BPA has estrogenic activity and is one of the most studied EDCs. We review evidence from studies in rodents using dose levels relevant to human exposure. BPA alters behavior and eliminates or in some cases reverses sexually dimorphic behaviors observed in unexposed animals.