Pharmacogenetic evaluation of ABCB1, Cyp2C9, Cyp2C19 and methylene tetrahydrofolate reductase polymorphisms in teratogenicity of anti-epileptic drugs in women with epilepsy

Seizure medication and planned pregnancy: balancing the risks and outcomes

INTRODUCTION

The therapeutic management of women with epilepsy (WWE) of childbearing age can be complicated by the need to balance maternal/fetal risks related to seizure occurrence during gestation with the potential teratogenic risks related to the use of anti-seizure medications (ASMs).

AREAS COVERED

The authors review clinical evidence on seizure-related and ASM-related risks during pregnancy. Current regulatory indications are discussed, evaluating their impact on clinical practice, and ethical implications of pharmacological decisions are debated.

EXPERT OPINION

If properly informed about the maternal/fetal risks carried by different pharmacological choices, WWE can become the final decision makers regarding their care in every phase of their life. Over the coming years, analysis of aggregated pregnancy registry data on the structural impact, on the fetus, of low doses of valproate and of newer ASMs, together with analysis of the main population study data on functional (cognitive and behavioral) outcomes, could lead to huge advances, making choosing an ASM a less complex process for the clinician and a less painful decision for the woman. Future objectives should include identification of the potential role of the pharmacogenomic profile of WWE in determining the risk of fetal malformations.

Precision medicine in women with epilepsy: The challenge, systematic review, and future direction

Epilepsy is one of the most prevalent neurologic conditions, affecting almost 70 million people worldwide. In the United States, 1.3 million women with epilepsy (WWE) are in their active reproductive years. Women with epilepsy (WWE) face gender-specific challenges such as pregnancy, seizure exacerbation with hormonal pattern fluctuations, contraception, fertility, and menopause. Precision medicine, which applies state-of-the art molecular profiling to diagnostic, prognostic, and therapeutic problems, has the potential to advance the care of WWE by precisely tailoring individualized management to each patient's needs. For example, antiseizure medications (ASMs) are among the most common teratogens prescribed to women of childbearing potential. Teratogens act in a dose-dependent manner on a susceptible genotype. However, the genotypes at risk for ASM-induced teratogenic deficits are unknown. Here we summarize current challenging issues for WWE, review the state-of-art tools for clinical precision medicine approaches, perform a systematic review of pharmacogenomic approaches in management for WWE, and discuss potential future directions in this field. We envision a future in which precision medicine enables a new practice style that puts focus on early detection, prediction, and targeted therapies for WWE.

Genetic Susceptibility to Drug Teratogenicity: A Systematic Literature Review

Since the 1960s, drugs have been known to cause teratogenic effects in humans. Such teratogenicity has been postulated to be influenced by genetics. The aim of this review was to provide an overview of the current knowledge on genetic susceptibility to drug teratogenicity in humans and reflect on future directions within the field of genetic teratology. We focused on 12 drugs and drug classes with evidence of teratogenic action, as well as 29 drugs and drug classes with conflicting evidence of fetal safety in humans. An extensive literature search was performed in the PubMed and EMBASE databases using terms related to the drugs of interest, congenital anomalies and fetal development abnormalities, and genetic variation and susceptibility. A total of 29 studies were included in the final data extraction. The eligible studies were published between 1999 and 2020 in 10 different countries, and comprised 28 candidate gene and 1 whole-exome sequencing studies. The sample sizes ranged from 20 to 9,774 individuals. Several drugs were investigated, including antidepressants (nine studies), thalidomide (seven studies), antiepileptic drugs (five studies), glucocorticoids (four studies), acetaminophen (two studies), and sex hormones (estrogens, one study; 17-alpha hydroxyprogesterone caproate, one study). The main neonatal phenotypic outcomes included perinatal complications, cardiovascular congenital anomalies, and neurodevelopmental outcomes. The review demonstrated that studies on genetic teratology are generally small, heterogeneous, and exhibit inconsistent results. The most convincing findings were genetic variants in SLC6A4, MTHFR, and NR3C1, which were associated with drug teratogenicity by antidepressants, antiepileptics, and glucocorticoids, respectively. Notably, this review demonstrated the large knowledge gap regarding genetic susceptibility to drug teratogenicity, emphasizing the need for further efforts in the field. Future studies may be improved by increasing the sample size and applying genome-wide approaches to promote the interpretation of results. Such studies could support the clinical implementation of genetic screening to provide safer drug use in pregnant women in need of drugs.

Maternal and neonatal complications during pregnancy in women with epilepsy

Epilepsy is the commonest serious neurological problem faced by obstetricians and gynaecologists. Epidemiological studies estimate epilepsy to complicate 0.3–0.7% of all pregnancies.1 2 The importance of epilepsy in pregnancy lies in the fact that many women with epilepsy (WWE) have to go through their pregnancy while taking antiepileptic (AED) drugs. Both the seizures and AEDs can have harmful effects on the mother as well the foetus. Thus, during pregnancy, the clinician faces dual challenge of controlling seizures as well as preventing teratogenicity of AEDs.1 In this review we discuss the possible impact of seizures as well as AEDs on mother as well as the child. We try to answer some of the commonest questions which are relevant to successful management of pregnancy and ensuring birth of a healthy baby.

Pharmacogenomics in Asia: a systematic review on current trends and novel discoveries

While early pharmacogenomic studies have primarily been carried out in Western populations, there has been a notable increase in the number of Asian studies over the past decade. We systematically reviewed all pharmacogenomic studies conducted in Asia published before 2016 to highlight trends and identify research gaps in Asia. We observed that pharmacogenomic research in Asia was dominated by larger developed countries, notably Japan and Korea, and mainly driven by local researchers. Studies were focused on drugs acting on the CNS, chemotherapeutics and anticoagulants. Significantly, several novel pharmacogenomic associations have emerged from Asian studies. These developments are highly encouraging for the strength of regional scientific and clinical community and propound the importance of discovery studies in different populations.

ABCB1 gene C3435T polymorphism and drug resistance in epilepsy: evidence based on 8,604 subjects

BACKGROUND

The present study aimed to assess the role of C3435T polymorphism in drug-resistance in epilepsy by a meta-analysis.

MATERIAL AND METHODS

Databases were obtained from the Cochrane Library, MEDLINE, EMBASE, PubMed, Science Direct database, CNKI, and Wanfang up to October 2014. All the case-control association studies evaluating the role of ABCB1 C3435T in pharmacoresistance to anti-epileptic drug (AED) were identified. RevMan 5.0 software was utilized to perform quantitative analyses in an allele model (C vs. T) and a genotype model (CC vs. CT+TT).

RESULTS

From the 189 potential studies, we included 28 articles for the meta-analysis, including 30 independent case-control studies involving 4124 drug-resistant epileptic patients and 4480 epileptic patients for whom drug treatment was effective. We excluded 164 studies because of duplication, lack of genotype data, and non-clinical research. We found that C3435T polymorphism was not significantly associated with drug resistance in epilepsy, either in allele model (C vs. T: OR=1.07; 95%CI: 0.95-1.19) or in genotype model (CC vs. CT+TT: OR=1.05; 95%CI: 0.89-1.24, P=0.55). Subgroup analyses suggested that in Caucasian populations there are significant differences between resistance group (NR) and control group (R) in both allele model (C vs. T: OR=1.09; 95%CI: 1.00-1.18, P=0.05) and genotype model (CC vs. CT+TT: OR=1.20; 95%CI: 1.04-1.40, P=0.01). However, we did not find this association in Asian populations.

CONCLUSIONS

We conclude that the ABCB1 C3435T polymorphism may be a genetic marker for drug resistance in epilepsy in Caucasian populations.