Association of LEPR and ANKK1 Gene Polymorphisms with Weight Gain in Epilepsy Patients Receiving Valproic Acid

Psychotropic drugs, eating behaviour and weight gain

PURPOSE OF REVIEW

Psychotropic drug related weight gain is a common side-effect of significant concern to both clinicians and patients. Recent studies and treatment guidelines strongly support taking preventive and early treatment approaches to psychotropic drug-related weight gain (PDWG). Arguably the main pathway that PDWG occurs is via changes in eating behaviour leading to increased caloric intake.

RECENT FINDINGS

Systematic reviews and meta-analyses have provided good data on the nature and prevalence of alterations in eating behaviour with psychotropic treatment including increased hunger, night eating and binge eating. These changes are unsurprisingly more prominent with agents like olanzapine and clozapine that have high propensity to cause weight gain.

SUMMARY

Altered eating behaviour can serve as an earlier measure of the risk of weight gain and can be examined easily in clinical practice. Detecting these changes can enable earlier action in terms of switching treatments and starting pharmacological and nonpharmacological preventive strategies.

Association of Valproic Acid and Its Main Metabolites' Plasma Concentrations with Clinical Outcomes among Epilepsy Patients: A 10-Year Retrospective Study Based on Therapeutic Drug Monitoring

Valproic acid (VPA) is a first-line antiepileptic drug with broad efficacy. Due to significant individual differences in its metabolism, therapeutic drug monitoring is commonly used. However, the recommended therapeutic range (50-100 μg/mL) is inadequate for predicting clinical outcomes. Additionally, the relationship between VPA metabolites and clinical outcomes remains unclear. In this retrospective study, 485 Chinese Southern Han epilepsy patients receiving VPA monotherapy were analyzed after reaching steady-state levels. Plasma concentrations of VPA and its five main metabolites were determined by liquid chromatography-mass spectrometry (LC-MS). We assessed the relevance of the recommended therapeutic VPA range for clinical outcomes and explored the association between VPA/metabolites levels and treatment efficacy/adverse effects. Vitro experiments were conducted to assess 4-ene-VPA hepatotoxicity. The therapeutic range of VPA exhibited no significant correlation with clinical outcomes, and plasma concentrations of VPA failed to serve as predictive indicators for treatment response/adverse effects. Treatment responders had higher 2-PGA concentrations (median, 26.39 ng/mL versus 13.68 ng/mL), with a threshold of 36.5 ng/mL for optimal epilepsy treatment. Patients with abnormal liver function had a higher 4-ene-VPA median concentration (6.41 μg/mL versus 4.83 μg/mL), and the ratio of 4-ene-VPA to VPA better predicted VPA-induced hepatotoxicity (area under the curve, 0.718) than 4-ene-VPA concentration. Vitro experiments revealed that 4-ene-VPA was more hepatotoxic than VPA in HepaRG and L02 cell lines. Total plasma VPA concentration does not serve as a predictor of clinical outcomes. 2-PGA concentrations may be associated with efficacy, whereas the ratio of 4-ene-VPA to VPA may be considered a better biomarker (threshold 10.03%) for VPA-induced hepatotoxicity. SIGNIFICANCE STATEMENT: This was the first and largest observational cohort in China to explore the relationship between patients' parent and metabolites concentrations of VPA and clinical outcomes during the maintenance of VPA monotherapy in epileptic patients. This study provided feasible references of VPA for epilepsy clinical treatment with a larger sample of patients compared with previous studies for a more definitive conclusion based on real-world situations. We found two potential biomarkers in predicting efficacy and liver injury, respectively. This breakthrough has the potential to assist in the rational use of VPA.

A study to investigate genetic factors associated with weight gain in people with diabetes: analysis of polymorphisms in four relevant genes

BACKGROUND

Weight change is often seen in people with diabetes. We investigated the effects of genes associated with weight change/glucose handling/insulin-signalling.

MATERIALS/METHODS

DNA from diabetes individuals and non-diabetes individuals, plus clinical data, were available from the DARE study (n = 379 individuals: T1D n = 111; T2D n = 222; controls n = 46). Weight gain was assessed by temporal change of Body Mass Index (BMI). Genotyping was performed for CAV1rs926198, LEPRrs1137101, BDNFrs6265 and FTOrs9939609.

RESULTS

No differences in genotype distributions were observed for the four SNPs in all groups un-stratified by weight gain. Following stratification differences in genotype distribution were observed. For those BMI relatively stable; controls showed a difference in genotype distributions versus T1D (CAV1rs926198, LEPRrs1137101). In T2D vs controls, significant differences were observed in genotype distribution for all four genes. For BMI increase, the only difference by category was LEPRrs1137101 (bothT1D/T2D vs controls). In BMI-stable groups, CAV1rs926198, T1D individuals showed lower T allele frequency (p=0.004) vs non-diabetes and for LEPRrs1137101 a higher G allele frequency versus controls (p=0.002). For T2D, CAV1rs926198, T allele frequency was lower in T2D than controls (p=0.005). For LEPR rs1137101, the G allele frequency was higher than in controls (p=0.004). In those with BMI increase, LEPRrs1137101 T1D individuals had higher G allele frequency versus controls (p=0.002) as did T2D vs controls (p=0.03).

CONCLUSION

Differences in allele frequency were seen between diabetes individuals and non-diabetes diagnosed at baseline in relation to the likelihood of BMI increase of >10%. It is established that the G allele of LEPRrs1137101 is associated with weight gain/obesity. However, this is the first report of CAV1rs926198 polymorphism being associated with weight stability/gain in diabetes.

Variation in prognosis and treatment outcome in juvenile myoclonic epilepsy: a Biology of Juvenile Myoclonic Epilepsy Consortium proposal for a practical definition and stratified medicine classifications

Reliable definitions, classifications and prognostic models are the cornerstones of stratified medicine, but none of the current classifications systems in epilepsy address prognostic or outcome issues. Although heterogeneity is widely acknowledged within epilepsy syndromes, the significance of variation in electroclinical features, comorbidities and treatment response, as they relate to diagnostic and prognostic purposes, has not been explored. In this paper, we aim to provide an evidence-based definition of juvenile myoclonic epilepsy showing that with a predefined and limited set of mandatory features, variation in juvenile myoclonic epilepsy phenotype can be exploited for prognostic purposes. Our study is based on clinical data collected by the Biology of Juvenile Myoclonic Epilepsy Consortium augmented by literature data. We review prognosis research on mortality and seizure remission, predictors of antiseizure medication resistance and selected adverse drug events to valproate, levetiracetam and lamotrigine. Based on our analysis, a simplified set of diagnostic criteria for juvenile myoclonic epilepsy includes the following: (i) myoclonic jerks as mandatory seizure type; (ii) a circadian timing for myoclonia not mandatory for the diagnosis of juvenile myoclonic epilepsy; (iii) age of onset ranging from 6 to 40 years; (iv) generalized EEG abnormalities; and (v) intelligence conforming to population distribution. We find sufficient evidence to propose a predictive model of antiseizure medication resistance that emphasises (i) absence seizures as the strongest stratifying factor with regard to antiseizure medication resistance or seizure freedom for both sexes and (ii) sex as a major stratifying factor, revealing elevated odds of antiseizure medication resistance that correlates to self-report of catamenial and stress-related factors including sleep deprivation. In women, there are reduced odds of antiseizure medication resistance associated with EEG-measured or self-reported photosensitivity. In conclusion, by applying a simplified set of criteria to define phenotypic variations of juvenile myoclonic epilepsy, our paper proposes an evidence-based definition and prognostic stratification of juvenile myoclonic epilepsy. Further studies in existing data sets of individual patient data would be helpful to replicate our findings, and prospective studies in inception cohorts will contribute to validate them in real-world practice for juvenile myoclonic epilepsy management.

Effect of ANKK1 Polymorphisms on Serum Valproic Acid Concentration in Chinese Han Adult Patients in the Early Postoperative Period

INTRODUCTION

This study aimed to investigate the relationship between gene polymorphisms and clinical factors with the concentrations of valproic acid (VPA) in adult patients who underwent neurosurgery in China.

METHODS

A total of 531 serum concentration samples at steady state were collected from 313 patients to develop a population pharmacokinetic (PPK) model. Data analysis was performed using nonlinear mixed effects modeling. Covariates included demographic parameters, biological characteristics, and genetic polymorphism. Bootstrap evaluation showed that the final model was stable. Sensitive analysis was performed to verify the relationship between gene polymorphisms and concentrations of VPA. Linear regression was used to analyze the relationship between VPA concentration, ANKK1, and daily dosage.

RESULTS

In the recruited patients, 17 of 25 single-nucleotide polymorphism distributions were consistent with the Hardy-Weinberg equilibrium. A one-compartment model with first-order absorption and elimination was developed for VPA injections. VPA clearance was significantly influenced by three variables: sex (17.41% higher in male than female patients), body weight, and the ANKK1 gene. Typical values for the elimination clearance and the volume of central compartment were 0.614 L/min and 23.5 L, respectively. The model evaluation indicated the stable and precise performance of the final model. After sensitive analysis using Kruskal-Wallis and Mann-Whitney U tests, we found that patients with AA alleles had higher VPA concentrations than those with GG and AG alleles. Linear regression models showed that gene polymorphisms of ANKK1 had little effects on VPA concentration.

CONCLUSION

A PPK model of VPA in Chinese Han patients was successfully established; this can be helpful for model-informed precision-dosing approaches in clinical patient care, and for exploring the mechanism of VPA-induced weight gain.

Therapeutic and Toxic Effects of Valproic Acid Metabolites

Valproic acid (VPA) and its salts are psychotropic drugs that are widely used in neurological diseases (epilepsy, neuropathic pain, migraine, etc.) and psychiatric disorders (schizophrenia, bipolar affective disorder, addiction diseases, etc.). In addition, the indications for the appointment of valproate have been expanding in recent years in connection with the study of new mechanisms of action of therapeutic and toxic metabolites of VPA in the human body. Thus, VPA is considered a component of disease-modifying therapy for multiple tumors, neurodegenerative diseases (Huntington's disease, Parkinson's disease, Duchenne progressive dystrophy, etc.), and human immunodeficiency syndrome. The metabolism of VPA is complex and continues to be studied. Known pathways of VPA metabolism include: β-oxidation in the tricarboxylic acid cycle (acetylation); oxidation with the participation of cytochrome P-450 isoenzymes (P-oxidation); and glucuronidation. The complex metabolism of VPA explains the diversity of its active and inactive metabolites, which have therapeutic, neutral, or toxic effects. It is known that some active metabolites of VPA may have a stronger clinical effect than VPA itself. These reasons explain the relevance of this narrative review, which summarizes the results of studies of blood (serum, plasma) and urinary metabolites of VPA from the standpoint of the pharmacogenomics and pharmacometabolomics. In addition, a new personalized approach to assessing the cumulative risk of developing VPA-induced adverse reactions is presented and ways for their correction are proposed depending on the patient's pharmacogenetic profile and the level of therapeutic and toxic VPA metabolites in the human body fluids (blood, urine).

A Longitudinal Study of the Association between the LEPR Polymorphism and Treatment Response in Patients with Bipolar Disorder

Patients with bipolar disorder (BD) exhibit individual variability in the treatment outcome, and genetic background could contribute to BD itself and the treatment outcome. Leptin levels significantly change in BD patients treated with valproate (VPA), but whether LEPR polymorphisms are associated with treatment response is still unknown. This longitudinal study aimed to investigate the associations between LEPR polymorphisms and VPA treatment response in BD patients who were drug naïve at their first diagnosis of BD. The single-nucleotide polymorphisms (SNPs) of LEPR (rs1137101, rs1137100, rs8179183, and rs12145690) were assayed, and the LEPR polymorphism frequencies of alleles and genotypes were not significantly different between the controls (n = 77) and BD patients (n = 130). In addition, after the 12-week course of VPA treatment in BD patients, the LEPR polymorphisms showed significant effects on changes in disease severity. Moreover, considering the effect of the LEPR haplotype, the frequency of the CAGG haplotype in BD patients was higher than that in the controls (9.3 vs. 2.9%, p = 0.016), and the LEPR CAGG haplotype was associated with a better treatment response than the other haplotypes in BD patients receiving VPA treatment. Therefore, LEPR polymorphisms might serve as mediators involved in the therapeutic action of VPA treatment.

Myotoxicity Induced by Antiepileptic Drugs: Could be a Rare but Serious Adverse Event?

Antiepileptic drugs (AEDs) are used in various pathologies such as including epilepsy, migraine, neuropathic pain, etc. They can improve symptoms but cause adverse events (ADRs). Case reports have reported that one rare but serious AED-induced adverse reaction that has appeared in case reports is myotoxicity from rhabdomyolysis. Rhabdomyolysis can be induced by a therapeutically dosed occur with therapeutic doses of antiepileptic drugs and is in most cases reversible, although rarely it can cause serious complications. Clinical manifestations of rhabdomyolysis range from a single isolated asymptomatic rise in serum CK levels to severe electrolyte imbalances, cardiac arrhythmia, acute and disseminated renal failure, intravascular coagulation, and other symptoms. Many clinical cases reported that both conventional older and newer AEDs, as well as propofol, can cause rhabdomyolysis, even if there are no conclusive data. It has recently been shown that genetic factors certainly contribute to adverse reactions of antiepileptic drugs. A study of genetic polymorphism in patients with AED-induced rhabdomyolysis may be useful to explain the rarity of this adverse event and to improve the treatment of these AED patients, in terms of AED type and dose adjustment.

Valproic Acid: A Promising Therapeutic Agent in Glioma Treatment

Glioma, characterized by infiltrative growth and treatment resistance, is regarded as the most prevalent intracranial malignant tumor. Due to its poor prognosis, accumulating investigation has been performed for improvement of overall survival (OS) and progression-free survival (PFS) in glioma patients. Valproic acid (VPA), one of the most common histone deacetylase inhibitors (HDACIs), has been detected to directly or synergistically exert inhibitory effects on glioma in vitro and in vivo. In this review, we generalize the latest advances of VPA in treating glioma and its underlying mechanisms and clinical implications, providing a clearer profile for clinical application of VPA as a therapeutic agent for glioma.

Pharmacogenomics of Medication-Induced Weight Gain and Antiobesity Medications

Obesity is a chronic, multifactorial disease associated with a large number of comorbidities. The clinical management of obesity involves a stepwise integrated approach, beginning with behavioral and lifestyle modification, followed by antiobesity medications, endobariatric procedures, and bariatric surgery. Weight gain and subsequent obesity are common side effects of medications, such as prednisone or antipsychotics. In this era of precision medicine, it is essential to identify patients at the highest risk of weight gain as a result of medication use. Pharmacogenomics could play an important role in obesity management by optimizing use of antiobesity medications as well as minimizing adverse weight gain. This review aims to provide a comprehensive analysis of the current literature on the role of pharmacogenomics in obesity and medication-induced weight gain. In summary, there are more robust studies of medication associated with weight gain and pharmacogenomics, and more studies are needed to understand the role of pharmacogenomics in antiobesity medications.

Pharmacogenomics of Cognitive Dysfunction and Neuropsychiatric Disorders in Dementia

Symptomatic interventions for patients with dementia involve anti-dementia drugs to improve cognition, psychotropic drugs for the treatment of behavioral disorders (BDs), and different categories of drugs for concomitant disorders. Demented patients may take >6–10 drugs/day with the consequent risk for drug–drug interactions and adverse drug reactions (ADRs >80%) which accelerate cognitive decline. The pharmacoepigenetic machinery is integrated by pathogenic, mechanistic, metabolic, transporter, and pleiotropic genes redundantly and promiscuously regulated by epigenetic mechanisms. CYP2D6, CYP2C9, CYP2C19, and CYP3A4/5 geno-phenotypes are involved in the metabolism of over 90% of drugs currently used in patients with dementia, and only 20% of the population is an extensive metabolizer for this tetragenic cluster. ADRs associated with anti-dementia drugs, antipsychotics, antidepressants, anxiolytics, hypnotics, sedatives, and antiepileptic drugs can be minimized by means of pharmacogenetic screening prior to treatment. These drugs are substrates, inhibitors, or inducers of 58, 37, and 42 enzyme/protein gene products, respectively, and are transported by 40 different protein transporters. APOE is the reference gene in most pharmacogenetic studies. APOE-3 carriers are the best responders and APOE-4 carriers are the worst responders; likewise, CYP2D6-normal metabolizers are the best responders and CYP2D6-poor metabolizers are the worst responders. The incorporation of pharmacogenomic strategies for a personalized treatment in dementia is an effective option to optimize limited therapeutic resources and to reduce unwanted side-effects.

Molecular pathway analysis associates alterations in obesity-related genes and antipsychotic-induced weight gain

OBJECTIVE

Antipsychotics often induce excessive weight gain. We hypothesised that individuals with genetic variations related to known obesity-risk genes have an increased risk of excessive antipsychotic-induced weight gain (AIWG). This hypothesis was tested in a subset of the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) trial data set.

METHODS

The CATIE trial compared effects and side effects of five different antipsychotics through an 18-month period. Based on the maximum weight gain recorded, excessive weight gain was defined as >7% weight gain. Cytoscape and GeneMANIA were instrumental in composing a molecular pathway from eight selected genes linked to obesity. Genetic information on a total of 495.172 single-nucleotide polymorphisms (SNPs) were available from 765 (556 males) individuals. Enrichment test was conducted through ReactomePA and Bioconductor. A permutation test was performed, testing the generated pathway against 105 permutated pathways (p ≤ 0.05). In addition, a standard genome-wide association study (GWAS) analysis was performed.

RESULT

GWAS analysis did not detect significant differences related to excessive weight gain. The pathway generated contained 28 genes. A total of 2067 SNPs were significantly expressed (p < 0.01) within this pathway when comparing excessive weight gainers to the rest of the sample. Affected genes including PPARG and PCSK1 were not previously related to treatment-induced weight gain.

CONCLUSIONS

The molecular pathway composed from high-risk obesity genes was shown to overlap with genetics of patients who gained >7% weight gain during the CATIE trial. This suggests that genes related to obesity compose a pathway of increased risk of excessive AIWG. Further independent analyses are warranted that may confirm or clarify the possible reasoning behind.

Genetic variations associated with pharmacoresistant epilepsy (Review)

Epilepsy is a common, serious neurological disorder worldwide. Although this disease can be successfully treated in most cases, not all patients respond favorably to medical treatments, which can lead to pharmacoresistant epilepsy. Drug-resistant epilepsy can be caused by a number of mechanisms that may involve environmental and genetic factors, as well as disease- and drug-related factors. In recent years, numerous studies have demonstrated that genetic variation is involved in the drug resistance of epilepsy, especially genetic variations found in drug resistance-related genes, including the voltage-dependent sodium and potassium channels genes, and the metabolizer of endogenous and xenobiotic substances genes. The present review aimed to highlight the genetic variants that are involved in the regulation of drug resistance in epilepsy; a comprehensive understanding of the role of genetic variation in drug resistance will help us develop improved strategies to regulate drug resistance efficiently and determine the pathophysiological processes that underlie this common human neurological disease.

Pharmacogenomic Characterization in Bipolar Spectrum Disorders

The holistic approach of personalized medicine, merging clinical and molecular characteristics to tailor the diagnostic and therapeutic path to each individual, is steadily spreading in clinical practice. Psychiatric disorders represent one of the most difficult diagnostic challenges, given their frequent mixed nature and intrinsic variability, as in bipolar disorders and depression. Patients misdiagnosed as depressed are often initially prescribed serotonergic antidepressants, a treatment that can exacerbate a previously unrecognized bipolar condition. Thanks to the use of the patient's genomic profile, it is possible to recognize such risk and at the same time characterize specific genetic assets specifically associated with bipolar spectrum disorder, as well as with the individual response to the various therapeutic options. This provides the basis for molecular diagnosis and the definition of pharmacogenomic profiles, thus guiding therapeutic choices and allowing a safer and more effective use of psychotropic drugs. Here, we report the pharmacogenomics state of the art in bipolar disorders and suggest an algorithm for therapeutic regimen choice.

Lipidomic characteristics and clinical findings of epileptic patients treated with valproic acid

Our early study has found valproic acid (VPA)-induced lipid dysmetabolism in animal model, however, the details of lipid profiling of VPA-treated epileptic patients remain unknown. Therefore, in this study, the blood samples of VPA-treated epileptic patients and VPA-free controls were collected for lipidomic and biochemical assays. As results, clinical data showed the changes of some blood lipid molecules in VPA-treated epileptic patients. In lipidomic assays, all 3797 annotated positive ions were identified prior to the data validation. In addition, the number of differentially expressed lipids were identified. And the 133 lipid molecules in VPA-treated cases were significantly up-regulated when compared to those in controls, while other 250 lipid metabolites were down-regulated. Further, these lipid metabolites were mainly constituted with glycerolipids, glycerophopholipids, fatty acyls, sterol lipids. In addition, the most significant elevations of metabolite molecules of triglyceride, sphingomyelin, phosphorylcholine, ceramides, phenolic phthiocerol, as well as topped reductions of phosphoethanolamines, diradylglycerols, 1α,25-dihydroxy-24-oxo-22-oxavitamin D3, 2-deoxy-20-hydroxy-5alpha-ecdysone 3-acetate, dolichyl-4 phosphate were identified respectively. Taken together, these clinical findings demonstrate that negative impacts of exposure to VPA on expression of lipid mediators, progressively disrupting the functions of lipid molecules. Interestingly, these differentially expressed metabolites may be potential biomarkers for screening VPA-induced dyslipidemia.

[Pharmacogenetic markers of metabolic disorders in the treatment with valproic acid]

The review includes studies on the association between the use of VA drugs and weight gain in patients with epilepsy as well as other valproate-induced adverse drug reactions, including insulin resistance. Understanding the mechanisms of significant weight gain of patients taking VA drugs will help personalize antiepileptic therapy and minimize the risk of valproate-induced obesity.

Polymorphisms of peroxisome proliferator-activated receptor γ (PPARγ) and cluster of differentiation 36 (CD36) associated with valproate-induced obesity in epileptic patients

RATIONALE

Valproate (VPA) is a choice for the treatment of primary generalized epilepsies and partial epilepsies. Unfortunately, weight gain or obesity is one of the most frequent adverse effects of VPA treatment. Genetic factors were shown to be involved in the effect.

OBJECTIVE

The aim of this study was to investigate the association of selected single nucleotide polymorphisms (SNPs) of cluster of differentiation 36 (CD36) and peroxisome proliferator-activated receptor γ (PPARγ) with VPA-induced weight gain and obesity in epileptic patients.

METHODS

A total of 225 Chinese Han epilepsy patients receiving VPA treatment were recruited in the study. Height and weight for the calculation of body mass index (BMI) were measured at the initiation of VPA therapy and in the follow-up examination. A BMI of 25 kg/m² or higher was defined as obesity on the basis of the World Health Organization (WHO) criteria for Asian populations. Four SNPs in CD36 (rs1194197, rs7807607) and PPARγ (rs10865710, rs2920502) were genotyped using the Sequenom^® MassArray iPlex platform.

RESULTS

About 19.6% of epileptic patients receiving VPA therapy were found to become obese. After covariate analysis of age, gender, sex, height, initial BMI, and VPA dosage, the CD36 rs1194197 C allele and rs7807607 T allele (OR, 0.31; 95%CI, 0.13-0.72; P = 0.009 and OR, 0.38; 95%CI; 0.18-0.83; P = 0.02, respectively) were identified as protective factors for VPA-induced obesity. The PPARγ rs10865710 C allele carriers were found to be less likely to suffer from VPA-induced obesity compared with GG genotype carriers (OR, 0.04; 95%CI, 0.01-0.12; P < 0.001). After a Bonferroni correction for multiple comparisons, the genotypic associations of CD36 rs1194197 and PPARγ rs10865710 and the allelic association of CD36 rs7807607 with obesity remained statistically significant.

CONCLUSIONS

Our data first indicated that CD36 and PPARγ polymorphisms may be associated with VPA-induced obesity and weight gain, suggesting that CD36 and PPARγ may have potential value in predicting VPA-induced obesity in Chinese Han epileptic patients.

Evaluation of association of DRD2 TaqIA and -141C InsDel polymorphisms with food intake and anthropometric data in children at the first stages of development

The reward sensation after food intake may be different between individuals and variants in genes related to the dopaminergic system may indicate a different response in people exposed to the same environmental factors. This study investigated the association of TaqIA (rs1800497) and -141C InsDel (rs1799732) variants in DRD2/ANKK1 gene with food intake and adiposity parameters in a cohort of children. The sample consisted of 270 children followed until 7 to 8 years old. DNA was extracted from blood and polymorphisms were detected by PCR-RFLP analysis. Food intake and nutritional status were compared among individuals with different SNP genotypes. Children carrying the A1 allele (TaqIA) had higher energy of lipid dense foods (LDF) when compared with A2/A2 homozygous children at 7 to 8 years old (GLM p=0.004; Mann Whitney p=0.005). No association was detected with -141C Ins/Del polymorphism. To our knowledge, this is the first association study of the DRD2 TaqIA and -141C Ins/Del polymorphism with food intake and anthropometric parameters in children. DRD2 TaqIA polymorphism has been associated with a reduction in D₂ dopamine receptor availability. Therefore, the differences observed in LDF intake in our sample may occur as an effort to compensate the hypodopaminergic functioning.

Population pharmacokinetics of valproic acid in epileptic children: Effects of clinical and genetic factors

Valproic acid (VPA) is a first-line anti-epileptic drug that is used in the treatment of generalized and partial seizures. Gene variants had been proved to influence the pharmacokinetics (PK) of VPA and contribute to its inter-individual variability (IIV). The aim of this study was to systematically investigate the effects of candidate gene variants (CYPs, UGTs, ABC transporters, and nuclear receptors) on VPA PK in Chinese children with epilepsy. A total of 1065 VPA serum trough concentrations at steady state were collected from 264 epileptic pediatric patients aged 3 months to 16 years. The population pharmacokinetic (PPK) model was developed using a nonlinear mixed effects modelling (NONMEM) approach. For the final PPK model, the oral clearance (CL/F) of VPA was estimated to be 0.259 L/h with IIV of 13.3%. The estimates generated by NONMEM indicated that the VPA CL/F was significantly influenced by patient body weight (increased by an exponent of 0.662), co-administration with carbamazepine (increased CL/F by 22%), and daily dose of VPA (increased by an exponent of 0.22). CL/F in patients with the LEPR rs1137101 variant (668 AG and GG genotypes) was much lower than in patients with the AA genotype (17.8% and 22.6% lower, respectively). However, none of the CYPs or UGTs gene variants was found to influence the PK of VPA in this study. Evaluation by bootstrap and normalized prediction distribution error (NPDE) showed that the final model was stable. The predictive performance was evaluated by goodness-of-fit (GOF) plots and visual predictive checks (VPC), and the results indicated satisfactory precision. Our model suggests a correlation between VPA CL/F and LEPR rs1137101 variants, which might be beneficial in the context of individual dose optimization.

The pharmacogenomics of valproic acid

Valproic acid is an anticonvulsant and mood-stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder. Adverse effects of valproic acid are rare, but hepatotoxicity is severe in particular in those younger than 2 years old and polytherapy. During valproic acid treatment, it is difficult for prescribers to predict its individual response. Recent advances in the field of pharmacogenomics have indicated variants of candidate genes that affect valproic acid efficacy and safety. In this review, a large number of candidate genes that influence valproic acid pharmacokinetics and pharmacodynamics are discussed, including metabolic enzymes, drug transporters, neurotransmitters and drug targets. Furthermore, pharmacogenomics is an important tool not only in further understanding of interindividual variability but also to assess the therapeutic potential of such variability in drug individualization and therapeutic optimization.

Pharmacogenomics in epilepsy

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Genetic variation can influence response to antiepileptic drug (AED) treatment through various effector processes.

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Metabolism of many AEDs is mediated by the cytochrome P450 (CYP) family; some of the CYPs have allelic variants that may affect serum AED concentrations.

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‘Precision medicine’ focuses on the identification of an underlying genetic aetiology allowing personalised therapeutic choices.

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Certain human leukocyte antigen, HLA, alleles are associated with an increased risk of idiosyncratic adverse drug reactions.

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New results are emerging from large-scale multinational efforts, likely imminently to add knowledge of value from a pharmacogenetic perspective.

There is high variability in the response to antiepileptic treatment across people with epilepsy. Genetic factors significantly contribute to such variability. Recent advances in the genetics and neurobiology of the epilepsies are establishing the basis for a new era in the treatment of epilepsy, focused on each individual and their specific epilepsy. Variation in response to antiepileptic drug treatment may arise from genetic variation in a range of gene categories, including genes affecting drug pharmacokinetics, and drug pharmacodynamics, but also genes held to actually cause the epilepsy itself.

From a purely pharmacogenetic perspective, there are few robust genetic findings with established evidence in epilepsy. Many findings are still controversial with anecdotal or less secure evidence and need further validation, e.g. variation in genes for transporter systems and antiepileptic drug targets. The increasing use of genetic sequencing and the results of large-scale collaborative projects may soon expand the established evidence.

Precision medicine treatments represent a growing area of interest, focussing on reversing or circumventing the pathophysiological effects of specific gene mutations. This could lead to a dramatic improvement of the effectiveness and safety of epilepsy treatments, by targeting the biological mechanisms responsible for epilepsy in each specific individual.

Whilst much has been written about epilepsy pharmacogenetics, there does now seem to be building momentum that promises to deliver results of use in clinic.

Inhibition of herpes virus infection in oligodendrocyte cultured cells by valproic acid

Valproic acid (VPA) is a small fatty acid used for treatment of different neurologic diseases such as epilepsy, migraines or bipolar disorders. VPA modulates different processes of cell metabolism that can lead to alterations in susceptibility of several cell types to the infection of Human Immunodeficiency Virus (HIV), Epstein-Barr virus (EBV), as well as to exert an inhibitory effect on the replication of different enveloped viruses in cultured cells. Taken these data into account and the fact that HSV-1 has been involved in some neuropathies, we have characterized the effect of VPA on this herpesvirus infection of the differentiation/maturation-inducible human oligodendrocyte cell line HOG, which resulted more susceptible to VPA inhibition of virus growth after cell differentiation. In these cells, the role of VPA in virus entry was tackled. Incubation with VPA induced a slight but reproducible inhibition in the virus particles uptake mainly observed when the drug was added in the adsorption or early upon infection. In addition, transcription and expression of viral proteins were significantly downregulated in the presence of VPA. Remarkably, when the infective viral production was assessed, VPA dramatically blocked the detection of infectious HSV-1 particles. Herein, our results indicate that VPA treatment of HOG cells significantly reduces the effect of HSV-1 infection, virus entry and productivity without affecting cellular viability.