A genome-wide association study of female sexual dysfunction

A survival of the fittest strategy for the selection of genotypes by which drug responders and non-responders can be predicted in small groups

Phenotype Prediction Scores (PPS) might be powerful tools to predict traits or the efficacy of treatments based on combinations of Single-Nucleotide Polymorphism (SNPs) in large samples. We developed a novel method to produce PPS models for small samples sizes. The set of SNPs is first filtered on those known to be relevant in biological pathways involved in a clinical condition, and then further filtered repeatedly in a survival strategy to select stabile positive/negative risk alleles. This method is applied on Female Sexual Interest/Arousal Disorder (FSIAD), for which two subtypes has been proposed: 1) a relatively insensitive excitatory system in the brain for sexual cues, and 2) a dysfunctional activation of brain mechanisms for sexual inhibition. A double-blind, randomized, placebo-controlled cross-over experiment was conducted on 129 women with FSIAD. The women received three different on-demand drug-combination treatments during 3 two-week periods: testosterone (0.5 mg) + sildenafil (50 mg), testosterone (0.5 mg) + buspirone (10 mg), or matching placebos. The resulted PPS were independently validated on patient-level and group-level. The AUC scores for T+S of the derivation set was 0.867 (95% CI = 0.796-0.939; p<0.001) and was 0.890 (95% CI = 0.778-1.000; p<0.001) on the validation set. For T+B the AUC of the derivation set was 0.957 (95% CI = 0.921-0.992; p<0.001) and 0.869 (95% CI = 0.746-0.992; p<0.001) for the validation set. Both formulas could reliably predict for each drug who benefit from the on-demand drugs and could therefore be useful in clinical practice.

Correlation of sexual dysfunction with sex hormone and estrogen receptor gene polymorphism in Chinese Han women with epilepsy

OBJECTIVE

Women with epilepsy (WWE) have a high risk of sexual dysfunction (SD). We aimed to investigate the incidence of SD, the correlation between SD, sex hormone and estrogen receptor (ER) gene polymorphism in Chinese Han WWE.

METHODS

This cross-sectional study examined 112 married WWE in the Affiliated Hospital of Yangzhou University who were taking antiepileptic drugs (AEDs) for ≥1 year, and 120 healthy controls without epilepsy, all of Chinese Han nationality. The age, menstruation, fertility of all the subjects and disease details of WWE were recorded. The Chinese version of female sexual function index (FSFI) was used to investigate the sexual function of the subjects. The chemiluminescence method was used for the detection of sex hormones, while polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to determine the ER gene polymorphism. The differences of the sexual function, sex hormone, ER genotype, and allele frequency were compared between the two groups. The correlation between SD, sex hormone and ER gene polymorphism was also analyzed.

RESULTS

(1) A high rate (70.5%) of SD was detected in WWE. (2) The serum prolactin (PRL) level (P = 0.039) and the ratio of estradiol to progesterone (E2/P) (P＜0.001) in the WWE group were significantly higher than those in the control group. The allele frequencies of ERα-PvuII C (P = 0.001) and ERβ-AluI A (P = 0.001) in the WWE group were significantly higher than those in the control group. (3) Binary logistic regression analysis showed that serum testosterone level [odds ratio (OR) = 0.412, 95 % confidence interval (CI): 0.201-0.842, P = 0.015], and PvuII CC genotype [odds ratio (OR) = 6.074, 95 % confidence interval (CI): 1.257-29.352, P = 0.025] were independently correlated with SD.

CONCLUSION

The incidence of SD in Chinese Han WWE is high. High serum testosterone levels may exert a protective effect on sexual function. ERα-PvuII polymorphism is related to the susceptibility of SD, and PvuII CC genotype may be the risk genotype of SD.

Genotype scores predict drug efficacy in subtypes of female sexual interest/arousal disorder: A double-blind, randomized, placebo-controlled cross-over trial

Attempts to develop a drug treatment for female sexual interest/arousal disorder have so far been guided by the principle of ‘one size fits all’, and have failed to acknowledge the complexity of female sexuality. Guided by personalized medicine, we designed two on-demand drugs targeting two distinct hypothesized causal mechanisms for this sexual disorder. The objective of this study was to design and test a novel procedure, based on genotyping, that predicts which of the two on-demand drugs will yield a positive treatment response. In a double-blind, randomized, placebo-controlled cross-over experiment, 139 women with female sexual interest/arousal disorder received three different on-demand drug-combination treatments during three 2-week periods: testosterone 0.5 mg + sildenafil 50 mg, testosterone 0.5 mg + buspirone 10 mg, and matching placebo. The primary endpoint was change in satisfactory sexual events. Subjects’ genetic profile was assessed using a microarray chip that measures 300,000 single-nucleotide polymorphisms. A preselection of single-nucleotide polymorphisms associated with genes that are shown to be involved in sexual behaviour were combined into a Phenotype Prediction Score. The Phenotype Prediction Score demarcation formula was developed and subsequently validated on separate data sets. Prediction of drug-responders with the Phenotype Prediction Score demarcation formula gave large effect sizes (d = 0.66 through 1.06) in the true drug-responders, and medium effect sizes (d = 0.51 and d = 0.47) in all patients (including identified double, and non-responders). Accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of the Phenotype Prediction Score demarcation formula were all between 0.78 and 0.79, and thus sufficient. The resulting Phenotype Prediction Score was validated and shown to effectively and reliably predict which women would benefit from which on-demand drug, and could therefore also be useful in clinical practice, as a companion diagnostic establishing the way to a true personalized medicine approach.

Impact of estrogen receptor α gene and oxytocin receptor gene polymorphisms on female sexuality

Over the past decades, research attention has increasingly been paid to the neurobiological component of sexual behavior. The aim of the present study was to investigate the correlation of estrogen receptor α (ERA) gene polymorphism (rs2234693-PvuII) (T→C substitution) and oxytocin receptor gene polymorphism (rs53576) (G→A substitution) with sexuality parameters of young, healthy women. One hundred thirty-three Greek heterosexual women, students in higher education institutions, 20-25 years of age, sexually active, with normal menstrual cycles (28-35 days), were recruited in the study. Exclusion criteria were chronic and/or major psychiatric diseases, use of oral contraceptive pills (OCs), polycystic ovary syndrome (PCOS), thyroid diseases as well as drugs that are implicated in hypothalamus-pituitary-gonadal axis. T allele (wildtype) of rs2234693 (PvuII) polymorphism of ERA gene was correlated with increased levels of arousal and lubrication, whereas A allele (polymorphic) of rs53576 (OXTR) polymorphism was correlated with increased arousal levels. The simultaneous presence of both T allele of rs2234693 (PvuII) and A allele of rs53576 (OXTR) polymorphisms (T + A group) was correlated with increased arousal, orgasm levels as well as female sexual function index full score. To our knowledge, this is the first study to investigate the interaction between ERA and OXTR with regard to sexual function in women. Female sexuality is a complex behavioral trait that encompasses both biological and psychological components. It seems that variability in female sexual response stems from genetic variability that characterizes endocrine, neurotransmitter and central nervous system influences.

Genomics and metabolomics of muscular mass in a community-based sample of UK females

The contribution of specific molecular-genetic factors to muscle mass variation and sarcopenia remains largely unknown. To identify endogenous molecules and specific genetic factors associated with appendicular lean mass (APLM) in the general population, cross-sectional data from the TwinsUK Adult Twin Registry were used. Non-targeted mass spec-based metabolomic profiling was performed on plasma of 3953 females (mostly dizygotic and monozygotic twins). APLM was measured using dual-energy X-ray absorptiometry (DXA) and genotyping was genome-wide (GWAS). Specific metabolites were used as intermediate phenotypes in the identification of single-nucleotide polymorphisms associated with APLM using GWAS. In all, 162 metabolites were found significantly correlated with APLM, and explained 17.4% of its variation. However, the top three of them (unidentified substance X12063, urate, and mannose) explained 11.1% (P ≤ 9.25 × 10(-26)) so each was subjected to GWAS. Each metabolite showed highly significant (P ≤ 9.28 × 10(-46)) associations with genetic variants in the corresponding genomic regions. Mendelian randomization using these SNPs found no evidence for a direct causal effect of these metabolites on APLM. However, using a new software platform for bivariate analysis we showed that shared genetic factors contribute significantly (P ≤ 4.31 × 10(-43)) to variance in both the metabolites and APLM--independent of the effect of the associated SNPs. There are several metabolites, having a clear pattern of genetic inheritance, which are highly significantly associated with APLM and may provide a cheap and readily accessible biomarker of muscle mass. However, the mechanism by which the genetic factor influences muscle mass remains to be discovered.

Gene expression changes in aging zebrafish (Danio rerio) brains are sexually dimorphic

Background

Brain aging is a multi-factorial process due to both genetic and environmental factors. The zebrafish has recently become a popular model organism for examining aging and age-related diseases because as in humans they age gradually and exhibit cognitive decline. Few studies have examined the biological changes in the aging brain that may contribute to these declines and none have examined them within individuals with respect to gender. Our aim was to identify the main genetic pathways associated with zebrafish brain aging across gender. We chose males and females from specific age groups (young, 7.5-8.5 months and old, 31-36 months) based on the progression of cognitive decline in zebrafish. RNA was isolated from individual brains and subjected to microarray and qPCR analysis. Statistical analyses were performed using a two-way ANOVA and the relevant post-hoc tests.

Results

Our results demonstrated that in the brains of young and old male and female zebrafish there were over 500 differentially expressed genes associated with multiple pathways but most notably were those related to neurogenesis and cell differentiation, as well as brain and nervous system development.

Conclusions

The gene expression of multiple pathways is altered with age and differentially expressed in males and females. Future studies will be aimed at determining the causal relationships of age-related changes in gene expression in individual male and female brains, as well as possible interventions that counteract these alterations.

Pharmacology of serotonin and female sexual behavior

In this review, first a historical perspective of serotonin's (5-HT) involvement in female sexual behavior is presented. Then an overview of studies implicating 5-HT is presented. The effect of drugs that increase or decrease CNS levels of 5-HT is reviewed. Evidence is presented that drugs which increase 5-HT have negative effects on female sexual behavior while a decrease in 5-HT is associated with facilitation of sexual behavior. Studies with compounds that act on 5-HT₁, 5-HT₂ or 5-HT₃ receptors are discussed. Most evidence indicates that 5-HT₁A receptor agonists inhibit sexual behavior while 5-HT₂ or 5-HT₃ receptors may exert a positive influence. There is substantial evidence to support a role for 5-HT in the modulation of female consummatory sexual behavior, but studies on the role of 5-HT in other elements of female sexual behavior (e.g. desire, motivation, sexual appetite) are few. Future studies should be directed at determining if these additional components of female sexual behavior are also modulated by 5-HT.

Bringing sex research into the 21st century: genetic and epigenetic approaches on female sexual function

Behavioral genetic evidence offers a useful way to disentangle some of the multifactorial etiological pathways toward the now clearly multidimensional construct of female sexual dysfunction (FSD) and has already shown its potential in providing a better understanding of the heterogeneous factors underlying FSD. Understanding the genetic basis and therefore physiologic key mechanisms of sexual function and dysfunction has the potential for improved treatments (i.e., the development of new medication) and ultimately prevention. However, genetic epidemiologic research into FSD is scarce and highlights the need for more in-depth exploration using larger samples and more accurate phenotypes. Knowledge gained from genetic studies also highlights the importance of environmental factors and gene-environment interactions in disease development and maintenance. Exploration of DNA epigenetic patterns that regulate gene expression profiles could therefore provide the missing link between epigenomic state and FSD, and as such may offer a new biological framework for the multifactorial pathoetiology underlying FSD.