Pharmacogenomics of multigenic diseases: sex-specific differences in disease and treatment outcome

The Role of Gender Pharmacogenetics in the Personalization of Drug Treatment

The use of pharmacogenetic guidelines in personalizing treatments has shown the potential to reduce interindividual variability in drug response by enabling genotype-matched dosing and drug selection. However, other important factors, such as patient gender, may interact strongly with pharmacogenetics in determining the individual profile of toxicity and efficacy but are still rarely considered when planning pharmacological treatment. The literature indicates that males and females respond differently to drugs, with women being at higher risk for toxicity and having different plasma exposure to drugs at standard doses. Recent studies have shown that pharmacogenetic variants may have different predictive value in different sexes, as in the case of treatment with opioids, angiotensin-converting enzyme inhibitors, or proton pump inhibitors. Of particular interest is the case of treatment with fluoropyrimidines for cancer. A significant increase in toxicity has been described in female patients, with a more pronounced effect of specific DPYD and TYMS polymorphisms also noted. This manuscript reviews the major findings in the field of sex-specific pharmacogenomics. SIGNIFICANCE STATEMENT: Interindividual variability in drug response is an emerging issue in pharmacology. The genetic profile of patients, as well as their gender, may play a role in the identification of patients more exposed to the risk of adverse drug reactions or poor efficacy. This article reviews the current state of research on the interaction between gender and pharmacogenetics in addressing interindividual variability.

Pharmacogenomic analysis of a genetically distinct Indigenous population

Indigenous Australians face a disproportionately severe burden of chronic disease relative to other Australians, with elevated rates of morbidity and mortality. While genomics technologies are slowly gaining momentum in personalised treatments for many, a lack of pharmacogenomic research in Indigenous peoples could delay adoption. Appropriately implementing pharmacogenomics in clinical care necessitates an understanding of the frequencies of pharmacologically relevant genetic variants within Indigenous populations. We analysed whole-genome sequence data from 187 individuals from the Tiwi Islands and characterised the pharmacogenomic landscape of this population. Specifically, we compared variant profiles and allelic distributions of previously described pharmacologically significant genes and variants with other population groups. We identified 22 translationally relevant pharmacogenomic variants and 18 clinically actionable guidelines with implications for drug dosing and treatment of conditions including heart disease, diabetes and cancer. We specifically observed increased poor and intermediate metabolizer phenotypes in the CYP2C9 (PM:19%, IM:44%) and CYP2C19 (PM:18%, IM:44%) genes.

The effects of sex on pharmacogenetically guided drug treatment

Tweetable abstract Sex-related pharmacogenetics is emerging area of research to better explain sex discrepancies in drug response. Sex pharmacogenetics should be considered an essential step for personalized medicine.

Demographic representation in clinical trials for cell-based therapy

Inclusion of women and minorities in clinical research is critical to fully assess the safety and efficacy of innovative therapies. With inadequate representation of demography, generalizability is impaired since pharmacokinetics and pharmacodynamics differ in these patient populations. This study was designed to analyze the voluntary participation rates of different demographic groups in cell-based therapy clinical trials conducted by the Interdisciplinary Stem Cell Institute (ISCI) at the University of Miami, Miller School of Medicine. ISCI conducted eight clinical trials between 2007 and 2017. The trials enrolled patients with ischemic and non-ischemic cardiomyopathy, idiopathic pulmonary fibrosis (IPF), aging-frailty, and Type-2 Diabetes. Participants received cell-based therapy (n = 218) or placebo (n = 33). Among the 251 participants, 29.5% were Hispanic and 20% were women. The proportion of individuals participating in each trial was compared to that of the respective disease populations attending University of Miami Health System clinics to calculate the participation to prevalence ratio (PPR). Distribution of women accurately reflected the population attending the University of Miami Health System in trials for dilated cardiomyopathy (DCM) and aging-frailty but was under-represented in others. Similarly, Hispanics and whites were accurately represented in three of the five disease fields, with Hispanics under-represented in frailty and diabetes, and whites over-represented in DCM and IPF. Black patients were accurately represented in the diabetes trial but were under-represented in all others. This study provides insight into challenges of achieving representative inclusion in research. Novel community engagement strategies are necessary to improve inclusion of women and under-represented minorities in clinical research of cell-based therapy.

Integrating NIMH Research Domain Criteria (RDoC) into PTSD Research

Three and a half decades of research on posttraumatic stress disorder (PTSD) has produced substantial knowledge on the pathobiology of this frequent and debilitating disease. However, despite all research efforts, so far no drug that has specifically targeted PTSD core symptoms progressed to clinical use. Instead, although not overly efficient, serotonin re-uptake inhibitors continue to be considered the gold standard of PTSD pharmacotherapy. The psychotherapeutic treatment and symptom-oriented drug therapy options available for PTSD treatment today show some efficacy, although not in all PTSD patients, in particular not in a substantial percent of those suffering from the detrimental sequelae of repeated childhood trauma or in veterans with combat related PTSD. PTSD has this in common with other psychiatric disorders - in particular effective treatment for incapacitating conditions such as resistant major depression, chronic schizophrenia, and frequently relapsing obsessive-compulsive disorder as well as dementia has not yet been developed through modern neuropsychiatric research.In response to this conundrum, the National Institute of Mental Health launched the Research Domain Criteria (RDoC) framework which aims to leave diagnosis-oriented psychiatric research behind and to move on to the use of research domains overarching the traditional diagnosis systems. To the best of our knowledge, the paper at hand is the first that has systematically assessed the utility of the RDoC system for PTSD research. Here, we review core findings in neurobiological PTSD research and match them to the RDoC research domains and units of analysis. Our synthesis reveals that several core findings in PTSD such as amygdala overactivity have been linked to all RDoC domains without further specification of their distinct role in the pathophysiological pathways associated with these domains. This circumstance indicates that the elucidation of the cellular and molecular processes ultimately decisive for regulation of psychic processes and for the expression of psychopathological symptoms is still grossly incomplete. All in all, we find the RDoC research domains to be useful but not sufficient for PTSD research. Hence, we suggest adding two novel domains, namely stress and emotional regulation and maintenance of consciousness. As both of these domains play a role in various if not in all psychiatric diseases, we judge them to be useful not only for PTSD research but also for psychiatric research in general.

Response to sertraline is influenced by GNβ3 gene G-350A variant in patients with major depressive disorder

PURPOSE

Heterotrimeric guanine nucleotide-binding proteins (G proteins) are a major group of human genome membrane protein receptors. Genetic variation in the β3 subunit (GNβ3) associated with gene splicing and increased activity is associated with major depressive disorder (MDD). However, the effect of G-350A GNβ3 genetic polymorphism and therapeutic outcome of selective serotonin reuptake inhibitors (SSRIs) in MDD has not yet been studied.

METHOD

One hundred newly diagnosed MDD patients were treated with sertraline for 6 weeks. The severity of depressive symptoms was weekly assessed by Hamilton Rating Scale for Depression (HRSD). A 50% decrease in HRSD was defined as response to treatment. GNβ3 polymorphisms (G-350A, A657T) were determined in each individual using a PCR-RFLP technique.

RESULTS

Our results suggested that subjects with GG genotype of G-350A responded 5.9-folds more to sertraline compared to carriers of other variants (P = 0.004, OR = 5.9; 95% CI = 1.66-21.99). In addition, carriers of the G allele responded 1.9-folds more to sertraline than carriers of the A allele (P = 0.032, OR = 1.92; 95% CI = 1.05-3.65). However, no association was observed between A657T variants and response to sertraline (P = 0.920, OR = 0.9; 95% CI = 0.31-2.69).

CONCLUSION

The results suggest that G-350A variant of GNβ3 plays a foremost part as a predictor of response to antidepressant treatment.

Population difference in the association of BDNF promoter methylation with mild cognitive impairment in the Xinjiang Uygur and Han populations

BACKGROUND

Mild cognitive impairment (MCI) is a clinical transitional stage between normal aging and Alzheimer disease, which leads to memory loss and a reduction in cognitive function. Brain derived neurotrophic factor (BDNF) plays an important role in neuronal development and plasticity. The aim of this study was to explore the association between BDNF promoter methylation and MCI in the Xinjiang Uygur and Han populations.

METHODS

A DNA methylation assay using bisulfite pyrosequencing technology was performed on 96 Uygur and 96 Han Chinese individuals from Xinjiang province, China.

RESULTS

We found a significantly higher BDNF methylation level in Han MCI cases than in Uygur MCI cases in males from Xinjiang province (p=0.022). In addition, the methylation level was significantly higher in Xinjiang Han healthy Chinese individuals (Northwestern China) than in Ningbo Han healthy Chinese individuals (Southeastern China) (Female and Male: p=1.17E-05; Female: p=0.020; Male: p=1.37E-04). But our results showed no significant association of BDNF methylation with MCI in either the Uygur or Han Chinese populations (p>0.05). Further gender-based subgroup analyses did not find any significant results (p>0.05).

CONCLUSION

Our results indicate that different levels of BDNF methylation may be present in different populations and environments. This study also provides further information regarding the relationship between BDNF methylation levels and MCI in Xinjiang Uygur and Han ethnic groups.

Influence of GNB3 C825T polymorphism on the efficacy of antidepressants in the treatment of major depressive disorder: A meta-analysis

OBJECTIVE

We performed the present meta-analysis in order to evaluate the influence of a common polymorphism (C825T, rs5443 C>T) in the GNB3 gene on the efficacy of antidepressants in the treatment of major depressive disorder (MDD).

METHOD

A relevant literature was searched using the PubMed, Embase, Web of Science, Cochrane Library, CISCOM, CINAHL, Google Scholar, CBM and CNKI databases without any language restrictions. STATA Version 12.0 software (Stata Corporation, College Station, Texas USA) was used for this meta-analysis. Odds ratio (OR) and its corresponding 95% confidence interval (95% CI) were calculated.

RESULTS

Our findings suggested that the GNB3 C825T polymorphism was significantly correlated with a higher response rate to antidepressants in MDD patients under the allele and dominant models. Furthermore, we found significant associations between GNB3 C825T polymorphisms and antidepressant-induced remission in MDD patients. Ethnicity-stratified analysis indicated that GNB3 C825T polymorphisms may be strongly related to the efficacy of antidepressants in the treatment of MDD among Asians, but not in Caucasians (all P>0.05).

CONCLUSION

Our findings provide empirical evidence that GNB3 C825T polymorphisms may be correlated with the efficacy of antidepressants in the treatment of MDD, especially among Asians patients.

Male-specific association between dopamine receptor D4 gene methylation and schizophrenia

Objective

The goal of our study was to investigate whether DRD4 gene DNA methylation played an important role in the susceptibility of Han Chinese SCZ.

Methods

Using the bisulphite pyrosequencing technology, DNA methylation levels of 6 CpG dinucleotides in DRD4 CpG island were measured among 30 paranoid SCZ patients, 30 undifferentiated SCZ patients, and 30 age- and gender-matched healthy controls.

Results

Strong correlation was observed among the six CpG sites (r>0.5, P<0.01), thus average methylation levels were applied thereafter. Our results indicated that there was a significant association between DRD4 methylation and the risk of SCZ (P = 0.003), although there was no significant difference in DRD4 methylation between the two SCZ subtypes (P = 0.670). A breakdown analysis by gender showed that the significant association of DRD4 methylation and SCZ was driven by males (P<0.001) but not by females (P = 0.835). DRD4 methylation was significantly associated with p300 in male SCZ patients (r = −0.543, P = 0.005) but not in female SCZ patients (r = 0.110, P = 0.599). Moreover, receiver operating characteristic (ROC) curves showed DRD4 methylation was able to predict the status of SCZ in males [area under curve (AUC) = 0.832, P = 0.002] but not in females (AUC = 0.483, P = 0.876). Finally, a further expression experiment showed that DRD4 methylation in the gene body was positively associated with gene expression, although the exact mechanism of gene regulation remained unknown for this interesting DRD4 methylation.

Conclusion

The gender disparity in the DRD4 DNA methylation provides novel insights into the pathogenesis of SCZ.

The role of nurse administrators and managers in quality psychiatric care

Psychiatric healthcare services in Japan demand continuous improvement to ensure quality care. Psychiatric nurse administrators and managers greatly influence the quality of services. To improve treatment, the following are considered necessary: clarification of service goal, proper assessment of treatment outcome, shortening of hospitalization, patient-centered care, establishment of trust relationships based on open communication with patients, and effective interdisciplinary teamwork. Additionally, administrators and managers must evaluate the clinical competence of individual nurses and appropriately assign them, especially when personnel shortage is an issue. Furthermore, in collaboration with other healthcare professionals, nurse managers must provide optimal care by setting goals of psychiatric services for patients in acute, sub-acute, or convalescent phases. This article presents the roles of nurse administrators and managers in improving the quality of Japanese psychiatric healthcare services.

Influence of catechol-O-methyltransferase (COMT) gene polymorphisms in pain sensibility of Brazilian fibromialgia patients

Fibromyalgia syndrome (FS) is a rheumatic syndrome affecting to 2-3% of individuals of productive age, mainly women. Neuroendocrine and genetic factors may play a significant role in development of the disease which is characterized by diffuse chronic pain and presence of tender points. Several studies have suggested an association between FS, especially pain sensitivity, and polymorphism of the catechol-O-methyltransferase (COMT) gene. The aim of the present study was to characterize the SNPs rs4680 and rs4818 of the COMT gene and assess its influence in pain sensitivity of patients with fibromyalgia screened by the Fibromyalgia Impact Questionnaire (FIQ). DNA was extracted from peripheral blood of 112 patients with fibromyalgia and 110 healthy individuals and was used as template in PCR for amplification of a 185-bp fragment of the COMT gene. The amplified fragment was sequenced for analyses of the SNPs rs4680 and rs4818. The frequency of mutant genotype AA of SNP rs6860 was 77.67% in patients with FS and 28.18% for the control group. For the SNP rs4818, the frequency of mutant genotype CC was 73.21 and 39.09% for patients with FS and controls, respectively. Moreover, the FIQ score was higher in patients with the homozygous mutant genotype for SNPs rs4680 (87.92 points) and rs4818 (86.14 points). These results suggest that SNPs rs4680 and rs4818 of the COMT gene may be associated with fibromyalgia and pain sensitivity in FS Brazilian patients.

Association of polymorphisms of the serotonergic system with smoking initiation in Caucasians

BACKGROUND

The serotonergic system may be implicated in susceptibility to nicotine dependence as nicotine increases 5-hydroxytryptamine (5-HT) release in brain and symptoms of nicotine withdrawal may be modulated by diminished serotonergic neurotransmission. We examined the association of polymorphisms of genes involved in release and receptor function of 5-HT with cigarette smoking initiation in subjects of Caucasian origin.

METHODS

5-HTTLPR polymorphism of the 5-HT transporter gene and -759C/T (rs3813929) and -697G/C (rs518147) polymorphisms of the 5-HT(2C) receptor gene were analyzed in 172 smoking initiators and 254 non-initiators, using PCR-RFLP method. Smoking behavior was assessed with a questionnaire about tobacco use.

RESULTS

We found no differences in the frequency of the 5-HTTLPR genotypes between smoking initiators and non-initiators. However, the frequency of 5-HT(2C) -759T allele was significantly higher in non-initiators than smoking initiators (29.5% vs 16.3%, p=0.002) and the same was true for 5-HT(2C) -697C allele carriers (48.8% vs 34.9%, p=0.004). Sex-dependent analysis revealed that these increased frequencies of -759T and -697C allele carriers were present only in males. No association was observed between any quantitative measures of smoking and these three polymorphisms.

CONCLUSIONS

5-HTTLPR polymorphism was not associated with smoking initiation in either male or female subjects. However, significant association was found between 5-HT(2C) receptor gene polymorphisms and smoking initiation in male Caucasian subjects.

The blood parasite Haemoproteus reduces survival in a wild bird: a medication experiment

While avian chronic haemoparasite infections induce reproductive costs, infection has not previously been shown to affect survival. Here, we experimentally reduced, through medication, the intensity of infection by Haemoproteus parasites in wild-breeding female blue tits Cyanistes caeruleus. However, this treatment did not reduce the intensity of infection in males or the intensity of infection by Leucocytozoon. Medicated females, but not males, showed increased local survival until the next breeding season compared with control birds. To our knowledge, this is the first empirical evidence showing long-term direct survival costs of chronic Haemoproteus infections in wild birds.

Can the host immune system promote multiple invasions of erythrocytes in vivo? Differential effects of medication and host sex in a wild malaria-like model

Multiple invasions (MIs) or infections, i.e. those by more than 1 parasite in the same erythrocyte, could be the result of parasite density or, alternatively, to parasite-related factors or host-related factors. According to the last possibility, to our knowledge, only 3 laboratory studies of malaria have found an increase in the occurrence of MIs when antibodies to parasite antigens were present. Therefore, we tested the possibility that MIs were influenced by the host immune status, using as model the malaria-like parasite Haemoproteus infecting blue tits (Cyanistes caeruleus). Avian hosts infected with Haemoproteus were medicated with primaquine or injected with saline solution and the density of infection and the presence of MIs counted. Medication treatment reduced significantly the density of infection by Haemoproteus in females but not in males. For females, the presence of MIs was positively associated with both the density of infection and the immunoglobulin levels on each capture, but no association was found between the treatment and the presence of MIs. For males, the density of infection but not the immunoglobulin levels was positively associated with the presence of MIs. In addition, medicated males supported more MIs than controls. Our results represent the first line of evidence in the wild for a possible role of the host immune system promoting MIs.

Allelic mRNA expression of X-linked monoamine oxidase a (MAOA) in human brain: dissection of epigenetic and genetic factors

A pVNTR repeat polymorphism located in the promoter region of the X-linked MAOA gene has been associated with mental disorders. To explore the effect of polymorphisms and epigenetic factors on mRNA expression, we have measured allelic expression imbalance (AEI) in female human brain tissue, employing two frequent marker single nucleotide polymorphisms (SNPs) in exon 8 (T890G) and exon 14 (C1409T) of MAOA. This approach compares one allele against the other in the same subject. AEI ratios ranged from 0.3 to 4 in prefrontal cortex, demonstrating the presence of strong cis-acting factors in mRNA expression. Analysis of CpG methylation in the MAOA promoter region revealed substantial methylation in females but not in males. MAOA methylation ratios for the three- and four-repeat pVNTR alleles of MAOA did not correlate with X-chromosome inactivation ratios, determined at the X-linked androgen receptor locus, suggesting an alternative process of dosage compensation in females. The extent of allelic MAOA methylation was highly variable and correlated with AEI (R2=0.5 and 0.7 at two CpG loci), indicating that CpG methylation regulates gene expression. Genetic factors appeared also to contribute to the AEI ratios. Genotyping of 13 MAOA polymorphisms in female subjects showed strong association with a haplotype block spanning from the pVNTR to the marker SNP. Therefore, allelic mRNA expression is affected by genetic and epigenetic events, both with the potential to modulate biogenic amine tone in the CNS.

Allelic expression of serotonin transporter (SERT) mRNA in human pons: lack of correlation with the polymorphism SERTLPR

An insertion/deletion polymorphism in the SERT linked promoter region (SERTLPR), previously reported to regulate mRNA expression in vitro, has been associated with mental disorders and response to psychotropic drugs. Contradictory evidence, however, has raised questions about the role of SERTLPR in regulating mRNA expression in vivo. We have used analysis of allelic expression imbalance (AEI) of SERT mRNA to assess quantitatively the contribution of SERTLPR to mRNA expression in human post-mortem pons tissue sections containing serotonergic neurons of the dorsal and median raphe nuclei. Any difference in the expression of one allele over the other indicates the presence of cis-acting elements that differentially affect transcription and/or mRNA processing and turnover. Using a marker SNP in the 3' untranslated region of SERT mRNA, statistically significant differences in allelic mRNA levels were detected in nine out of 29 samples heterozygous for the marker SNP. While the allelic expression differences were relatively small (15-25%), they could nevertheless be physiologically relevant. Although previous results had suggested that the long form of SERTLPR yields higher mRNA levels than the short form, we did not observe a correlation between SERTLPR and allelic expression ratios. Also in contrast to previous results, we found no correlation between SERTLPR and allelic expression ratios or SERT mRNA levels in B-lymphocytes. This study demonstrates that regulation of SERT mRNA is independent of SERTLPR, but could be associated with polymorphisms in partial linkage disequilibrium with SERTLPR.

Pharmacogenetics/genomics and personalized medicine

Despite the marked advances in drug therapy, some patients do not respond favorably or suffer severe adverse drug effects. Pharmacogenetic studies have shown that polymorphisms of drug metabolizing enzymes, transporters and receptors contribute to variable drug response. Owing to the complexity of drug actions, a broader genomics approach aims at finding new drug targets and optimizing therapy for the individual patient. However, pharmacogenomics has made only a few inroads into clinical practice to date. This review evaluates obstacles that need to be overcome. These include the complexity of mechanisms underlying drug response, given singly or in combination, uncertainty about the genetic underpinnings of complex diseases, such as cancer, diabetes, cardiovascular and mental disorders and a lack of quantitative understanding of the scope of genetic variations, even for well-studied genes. By resolving these hurdles, pharmacogenomics will yield significant, but incremental, therapeutic advances paving the way towards personalized health care.