Personalized psychiatry: a realistic goal

Biomarker identification in psychiatric disorders: from neuroscience to clinical practice

Patients with psychiatric disorders exhibit several neurobehavioral and neuropsychological alterations compared to healthy controls. However, signature endpoints of these behavioral manifestations have not yet been translated into clinical tests for diagnosis and follow-up measures. Recently, neuroproteomic approaches have been utilized to identify unique signature markers indicative of these disorders. Development of reliable biomarkers has the potential to revolutionize the diagnosis, classification, and monitoring of clinical responses in psychiatric diseases. However, the lack of biological gold standards, the evolving nosology of psychiatric disorders, and the complexity of the nervous system are among the major challenges that have hindered efforts to develop reliable biomarkers in the field of neuropsychiatry and drug abuse. While biomarkers currently have a limited role in the area of neuropsychiatry, several promising biomarkers have been proposed in conditions such as dementia, schizophrenia, depression, suicide, and addiction. One of the primary objectives of this review is to discuss the role of proteomics in the development of biomarkers specific to neuropsychiatry. We discuss and evaluate currently available biomarkers as well as those that are under research for clinical use in the future.

Significance of dietary folate intake, homocysteine levels and MTHFR 677 C>T genotyping in South African patients diagnosed with depression: test development for clinical application

Low folate intake in the presence of the functional MTHFR 677 C > T (rs1801133) polymorphism is an important cause of elevated homocysteine levels previously implicated in major depressive disorder (MDD) and many other chronic diseases. In this study the clinical relevance and inter-relationship of these aspects were evaluated in 86 South African patients diagnosed with MDD and 97 population-matched controls participating in a chronic diseases screening program. A questionnaire-based clinical and nutrition assessment was performed, homocysteine levels determined, and all study participants genotyped for MTHFR 677 C > T (rs1801133) using allele-specific TaqMan technology. The folate score was found to be significantly lower in the patient group compared to controls (p = 0.003) and correlated with increased body mass index (BMI), particularly in females with MDD (p = 0.009). BMI was significantly higher in the MDD patients compared with controls after adjustment for age and sex (p = 0.015), but this association was no longer significant after further adjustment for the level of folate intake in the diet. In MDD patients but not controls, the minor T-allele of MTHFR 677 C > T was associated with increased BMI (p = 0.032), which in turn correlated significantly with increased homocysteine levels. The significant association between BMI and homocysteine levels was observed in both the MDD patient (p = 0.049) and control (p = 0.018) study groups. The significantly higher homocysteine levels observed in MDD patients compared to controls after adjustment for age and sex (p = 0.030), therefore appears to be mediated by the effects of MTHFR 677 C > T and low folate intake on BMI. Detection of the low-penetrance MTHFR 677 C > T mutation reinforces the importance of folate intake above the recommended daily dose to prevent or restore dysfunction of the methylation pathway.

Rethinking psychiatry with OMICS science in the age of personalized P5 medicine: ready for psychiatome?

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is universally acknowledged as the prominent reference textbook for the diagnosis and assessment of psychiatric diseases. However, since the publication of its first version in 1952, controversies have been raised concerning its reliability and validity and the need for other novel clinical tools has emerged. Currently the DSM is in its fourth edition and a new fifth edition is expected for release in 2013, in an intense intellectual debate and in a call for new proposals. Since 1952, psychiatry has undergone many changes and is emerging as unique field in the medical area in which a novel approach is being demanded for properly treating patients: not the classical “one-size-fits-all” approach, but a more targeted and tailored diagnosis and therapeutics, taking into account the complex interactions among genes and their products, environment, culture and the psychological apparatus of the subject. OMICS sciences, being based on high-throughput technologies, are systems biology related fields (like genomics, proteomics, transcriptomics and so on). In the frame of the P5 medicine (personalized, participatory, predictive, preventive, psycho-cognitive), they could establish links between psychiatric diseases, which are disorders with a final common symptomatology with vastly heterogeneous biological, environmental and sociological underpinnings, and by understanding the psychiatric diseases beyond their classic symptomatic or syndromal definitions using OMICS research, one can have a broader picture and unprecedented links and reclassification of psychiatric nosology. Importantly, by understanding the basis of heterogeneity in diseases through OMICS research, one could also personalize treatment of psychiatric illnesses. In this manuscript, we discuss a gap in the current psychiatric research, namely the missing logical link among OMICS, personalized medicine and reclassification of diseases. Moreover, we explore the importance of incorporating OMICS-based quantitative dimensional criteria, besides the classical qualitative and categorical approach.

Why has it taken so long for biological psychiatry to develop clinical tests and what to do about it?

Patients with mental disorders show many biological abnormalities which distinguish them from normal volunteers; however, few of these have led to tests with clinical utility. Several reasons contribute to this delay: lack of a biological 'gold standard' definition of psychiatric illnesses; a profusion of statistically significant, but minimally differentiating, biological findings; 'approximate replications' of these findings in a way that neither confirms nor refutes them; and a focus on comparing prototypical patients to healthy controls which generates differentiations with limited clinical applicability. Overcoming these hurdles will require a new approach. Rather than seek biomedical tests that can 'diagnose' DSM-defined disorders, the field should focus on identifying biologically homogenous subtypes that cut across phenotypic diagnosis--thereby sidestepping the issue of a gold standard. To ensure clinical relevance and applicability, the field needs to focus on clinically meaningful differences between relevant clinical populations, rather than hypothesis-rejection versus normal controls. Validating these new biomarker-defined subtypes will require longitudinal studies with standardized measures which can be shared and compared across studies--thereby overcoming the problem of significance chasing and approximate replications. Such biological tests, and the subtypes they define, will provide a natural basis for a 'stratified psychiatry' that will improve clinical outcomes across conventional diagnostic boundaries.

Human lymphoblastoid cell line panels: novel tools for assessing shared drug pathways

Aims: While powerful in silico tools are emerging for predicting drug targets and pathways, general in vitro tools for assessing such predictions are lacking. We present a novel in vitro method for distinguishing shared versus distinct drug pathways based on comparative cell growth inhibition profiles across a small panel of human lymphoblastoid cell lines (LCLs) from individual donors. Materials & methods: LCLs from unrelated healthy donors were examined in parallel for growth inhibition profiles of various drugs, including antidepressants (paroxetine, fluoxetine, fluvoxamine, citalopram, amitriptyline and imipramine); anticancer drugs (5-fluorouracil, 6-mercaptopurine, azathioprine, methotrexate and resveratrol); steroid drugs (dexamethasone, beclomethasone and prednisolone); and antipsychotic drugs (haloperidol and clozapine). Cell growth was assessed by the colorimetric 2,3-bis(2-methoxy-4-nitro-5-sulfophenly)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide method following 72 h of drug exposure. Results: LCLs from unrelated individuals exhibited a wide range of sensitivities to growth inhibition by a given drug, which were independent of basal cell replication rates. Yet, each individual cell line demonstrated a consistent sensitivity to multiple drugs from the same family. High goodness-of-fit values (R2 > 0.6) were consistently observed for plots comparing the growth-inhibition profiles for paired drugs sharing a similar pathway, for example antidepressants, steroid drugs, antipsychotics, or 6-mercaptopurine compared with azathioprine, but not for drugs with different pathways. The method’s utility is demonstrated by the observation that chlorpheniramine, an antihistamine drug long suspected to also possess antidepressant-like properties, exhibits a growth-inhibition profile very similar to antidepressants. Conclusion: Comparing the growth-inhibition profiles of drugs (or compounds) of interest with the profiles of drugs with known pathways may assist in drug pathway classification. The method is useful for in vitro assessment of in silico-generated drug pathway predictions and for distinguishing shared versus distinct pathways for compounds of interest. Comparative transcriptomics analysis of human lymphoblastoid cell lines exhibiting ‘edge’ sensitivities can subsequently be utilized in the search for drug response biomarkers for personalized pharmacotherapy. The limitations and advantages of the method are discussed.

Need for reassessment of reported CYP2C19 allele frequencies in various populations in view of CYP2C19*17 discovery: the case of Greece

Introduction: CYP2C19*17 is a novel variant allele causing ultrarapid metabolism of CYP2C19 substrates. In the present study we investigated the CYP2C19*17 allelic frequency and recalculated previously reported frequencies of the CYP2C19*1/*1 genotype and of all genotype-derived phenotypes for CYP2C19 in the Greek population. Materials & methods: A total of 283 nonrelated healthy Greek ethnic subjects that had already been genotyped for CYP2C19*2 and *3 alleles as well as for CYP2D6 and CYP2C9 variant alleles participated in the study. The CYP2C19*17 allele was genotyped by the PCR-RFLP method. Results: The CYP2C19*17 allele frequency was 19.61%. The prevalence of CYP2C19*17 carriers in the Greek population was estimated at 31.80%, while the frequency of CYP2C19*1/*1 genotype was recalculated to 44.17% from 75.97% in our previous study. Several subjects possessing both CYP2C19*17 and variant alleles of CYP2D6 and CYP2C9 were also identified. Discussion & conclusion: The CYP2C19*17 allele is present in Greeks at a high frequency similar to that found in other European populations of Caucasian origin. Our study highlights the need of reassessing and updating CYP2C19 allelic frequencies in various populations in view of the major role that CYP2C19*17 may have in predicting the clinical outcome of drugs metabolized by CYP2C19.

A call for the creation of personalized medicine databases

The success of the Human Genome Project raised expectations that the knowledge gained would lead to improved insight into human health and disease, identification of new drug targets and, eventually, a breakthrough in healthcare management. However, the realization of these expectations has been hampered by the lack of essential data on genotype--drug-response phenotype associations. We therefore propose a follow-up to the Human Genome Project: forming global consortia devoted to archiving and analysing group and individual patient data on associations between genotypes and drug-response phenotypes. Here, we discuss the rationale for such personalized medicine databases, and the key practical and ethical issues that need to be addressed in their establishment.

Ethnic differences in CYP2C9*2 (Arg144Cys) and CYP2C9*3 (Ile359Leu) genotypes in Japanese and Israeli populations

CYP2C9 is a major P450 2C enzyme, which hydroxylates about 16% of drugs that are in current clinical use and contributes to the metabolism of a number of clinically important substrate drugs such as warfarin. Ethnic differences in the genetic variation of CYP2C9 have been reported, and might be related to the frequencies of adverse reactions to drugs metabolized by CYP2C9 in different ethnic groups. In the present study, ethnic differences in the CYP2C9*2 and CYP2C9*3 allele distribution in Japanese and Israeli populations were evaluated using a newly developed oligonucleotide based DNA array (OligoArray(R)). The population studied consisted of 147 Japanese and 388 Israeli donors (100 Ashkenazi Jews, 99 Yemenite Jews, 100 Moroccan Jews and 89 Libyan Jews). The CYP2C9*2 [Arg144Cys (416 C>T), exon 3] and CYP2C9*3 [Ile359Leu (1061 A>C), exon 7] genotypes were determined using an OligoArray(R). The accuracy of genotyping by the OligoArray(R) was verified by the fluorescent dye-terminator cycle sequencing method. A Hardy-Weinberg test indicated equilibrium (chi(2)<3.84 is Hardy-Weinberg) in all populations. The CYP2C9*2 genotype (CC/CT+TT) was absent in Japanese (1/0) (OR 0.02), and its frequency was significant in Libyan Jews (0.697/0.303) (OR 2.13; 95% CI 1.07-4.24) compared with Ashkenazi Jews (0.83/0.17), Yemenite Jews (0.899/0.101), and Moroccan Jews (0.81/0.19). The frequencies of CYP2C9*3 genotype (AA/AC+CC) was significantly lower in Japanese (0.986/0.014) (OR 0.08), and was higher in Libyan Jews (0.652/0.348) (OR 3.03; 95% CI 1.5-6.1) and Moroccan Jews (0.77/0.23) (OR 1.69; 95% CI 0.62-3.48) compared with those in Ashkenazi Jews (0.85/0.15) and Yemenite Jews (0.849/0.151). Thus, the CYP2C9*2 (Arg144Cys) and CYP2C9*3 (Ile359Leu) variants were rare in the Japanese population, and showed different frequencies in the four Jewish ethnic groups examined.

Pharmacogenomics Education: International Society of Pharmacogenomics Recommendations for Medical, Pharmaceutical, and Health Schools Deans of Education

Pharmacogenomics would be instrumental for the realization of personalized medicine in coming decades. Efforts are evident to clarify the potential bioethical, societal, and legal implications of key pharmacogenomics-based technologies projected to be soon introduced into the core practice of medicine. In sharp contrast, a lack of sufficient attention to educational aspects of pharmacogenomics, both for professionals and for society at large, is evident. In order to contribute to this discussion, a 'Pharmacogenomics Education Forum' was held on October 2, 2004 during the 3rd Annual Meeting of the International Society of Pharmacogenomics (ISP) at Santorini, Greece. The participants, members of the ISP Pharmacogenomics Education Forum, after deliberate discussions, proposed a document of 'Background Statement' and 'Recommendations and Call for Action' addressed to Deans of Education at Medical, Pharmaceutical, and Health Schools globally. This document has been considered by the education committee of the International Society of Pharmacogenomics and the result is presented here. We hope that this call would be listened to, and soon followed by beneficial action, ultimately leading to enhanced implementation of personalized medicine into core medical education and practice.

From pharmacogenetics to personalized medicine: a vital need for educating health professionals and the community

The field of pharmacogenetics will soon celebrate its 50th anniversary. Although science has delivered an impressive amount of information in these 50 years, pharmacogenetics has suffered from lack of integration into clinical practice. There are several reasons for this, including the unmet need for education at medical schools and the lack of awareness about the impact of genetic medicine on healthcare in the community. Recently, the FDA announced that it considers pharmacogenomics one of three major opportunities on the critical path to new medical products. This notion by the FDA is filling the regulatory void that existed between drug developers and drug users. However, in order to bring pharmacogenetic testing to the prescription pad successfully, healthcare professionals and policy makers, as well as patients, need to have the necessary background knowledge for making educated treatment decisions. To effectively move pharmacogenetics into everyday medicine, it is therefore imperative for scientists and teachers in the field to take on the challenge of disseminating pharmacogenetic insights to a broader audience.