A systematic review of common genetic variation and biological pathways in autism spectrum disorder

Background

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by persistent deficits in social communication and interaction. Common genetic variation appears to play a key role in the development of this condition. In this systematic review, we describe the relationship between genetic variations and autism. We created a gene dataset of the genes involved in the pathogenesis of autism and performed an over-representation analysis to evaluate the biological functions and molecular pathways that may explain the associations between these variants and the development of ASD.

Results

177 studies and a gene set composed of 139 were included in this qualitative systematic review. Enriched pathways in the over-representation analysis using the KEGG pathway database were mostly associated with neurotransmitter receptors and their subunits. Major over-represented biological processes were social behavior, vocalization behavior, learning and memory. The enriched cellular component of the proteins encoded by the genes identified in this systematic review were the postsynaptic membrane and the cell junction.

Conclusions

Among the biological processes that were examined, genes involved in synaptic integrity, neurotransmitter metabolism, and cell adhesion molecules were significantly involved in the development of autism.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-021-00662-z.

Maternal Nutrition and Neurodevelopment: A Scoping Review

In this scoping review, we examined the association between maternal nutrition during pregnancy and neurodevelopment in offspring. We searched the Pubmed and ScienceDirect databases for articles published from 2000 to 2020 on inadequate intake of vitamins (B12, folate, vitamin D, vitamin A, vitamin E, vitamin K), micronutrients (cooper, iron, creatine, choline, zinc, iodine), macronutrients (fatty acids, proteins), high fat diets, ketogenic diets, hypercaloric diets, and maternal undernutrition. Some older relevant articles were included. The search produced a total of 3590 articles, and 84 studies were included in the qualitative synthesis. Data were extracted and analyzed using charts and the frequency of terms used. We concluded that inadequate nutrient intake during pregnancy was associated with brain defects (diminished cerebral volume, spina bifida, alteration of hypothalamic and hippocampal pathways), an increased risk of abnormal behavior, neuropsychiatric disorders (ASD, ADHD, schizophrenia, anxiety, depression), altered cognition, visual impairment, and motor deficits. Future studies should establish and quantify the benefits of maternal nutrition during pregnancy on neurodevelopment and recommend adequate supplementation.

Possible Genetic Determinants of Response to Phenytoin in a Group of Colombian Patients With Epilepsy

Background

Epilepsy is a serious health problem worldwide. Despite the introduction of new antiepileptic drugs (AEDs) almost 30% of these patients have drug-resistant forms of the disease (DRE), with a significant increase in morbi-mortality.

Objective

Our objective was to assess the impact of some genetic factors and its possible association with treatment response and adverse drug reactions (ADRs) to phenytoin in 67 adult Colombian patients with epilepsy.

Methods

We conducted an analytical, observational, prospective cohort study to screen four polymorphisms in pharmacogenes: CYP2C9*2-c.430C>T (rs1799853), CYP2C9*3-c.1075A>C (rs1057910), ABCB1-c.3435T>C (rs1045642), and SCN1A-IVS5-91G>A (rs3812718), and their association with treatment response. Patients were followed for 1 year to confirm the existence of DRE (non-response) and ADRs using an active pharmacovigilance approach, followed by a consensus in order to classify ADRs according to causality, preventability, intensity and their relation with phenytoin dose, the duration of treatment, and susceptibility factors (DoTS methodology).

Results

A little more than half of evaluated subjects (52.2%) were non-responding to phenytoin. Regarding the genotype-phenotype correlation there was no association between polymorphisms of SCN1A and ABCB1 and DRE (non-response) (p = 0.34), and neither with CYP2C9 polymorphisms and the occurrence of ADRs (p = 0.42). We only found an association between polymorphic alleles of CYP2C9 and vestibular-cerebellar ADRs (dizziness, ataxia, diplopia, and dysarthria) (p = 0.001). Alleles CYP2C9*2-c.430C>T and CYP2C9*3-c.1075A>C were identified as susceptibility factors to ADRs in 24% of patients.

Conclusions

Decreased function alleles of CYP2C9 were highly predictive of vestibular-cerebellar ADRs to phenytoin in our study (p = 0.001). However, the genetic variants CYP2C9*2-c.430C>T, CYP2C9*3-c.1075A>C, ABCB1-c.3435T>C, and SCN1A-IVS5-91G>A, were not associated with treatment response in our study.

Safety liver profile of teriflunomide versus interferon β in multiple sclerosis: Systematic review and indirect comparison meta-analysis

OBJECTIVES

To compare the liver safety profile of interferon β (IFN β) and teriflunomide in patients with multiple sclerosis.

METHODS

A network meta-analysis was carried out following the Cochrane Collaboration methodology. All trials comparing all types of IFN β with teriflunomide, or disease-modifying drugs, or placebo in RRMS were included. An indirect comparison network meta-analysis within a Bayesian framework with STATA (version 13.0) was done for this study.

RESULTS

The database searches yielded 284 titles, with 15 records as duplicates. One study was identified by manually searching. Thirteen articles were included in the systematic review. Twelve studies compared IFN β (4203 patients) vs another DMT. Four studies evaluated the effectiveness and safety of teriflunomide (906 patients) vs another DMT. Six studies reported drug-induced liver injury as per the Hy's Law. However, only one study had a direct comparison and reported no cases of liver toxicity in either group, so it was not possible to estimate the OR. The indirect comparisons metanalysis shows that there was no statistically-significant difference between teriflunomide and IFN β (OR 1.09, 95% CI 0.02-2.16).

CONCLUSIONS

There were no significant difference when comparing IFN β and teriflunomide in terms of liver failure or elevation of transaminases.

Leptin: role over central nervous system in epilepsy

Adipose tissue is a dynamic organ with different effects on the body. Many of these effects are mediated by leptin, a hormone strongly involved in regulation of feeding and energy metabolism. It has an important role as a mediator of neuronal excitatory activity and higher brain functions. The aim of this study was to review the association between leptin and cerebral neuronal function, in particular its anticonvulsant or convulsant effects and the possible therapeutic role for treating epilepsy. For this purpose, the databases Pubmed, Science Direct, Elsevier, ResearchGate and Scielo were searched to identify experimental studies, reviews and systematic review articles, published in English, Spanish or Portuguese. Experimental studies and the presence of leptin receptors in nervous system sites other than the hypothalamus suggest an influence on higher brain functions. Indeed several animal studies have demonstrated a role of these channels in epileptiform activity as both anticonvulsive and convulsive effects have been found. The reason for these discrepancies is unclear but provides clear evidence of a potential role of leptin and leptin therapy in epileptiform activity. The association between leptin and brain function demonstrates the importance of peripheral metabolic hormones on central nervous system and opens a new way for the development of novel therapeutic interventions in diseases like epilepsy. Nevertheless further investigations are important to clarify the dynamics and diverse actions of leptin on excitatory regulation in the brain.

Learning skills and academic performance in children and adolescents with absence epilepsy

INTRODUCTION

Although cognitive and learning disorders have been described in patients with epilepsy, very few studies focus on specific disorders such as absence epilepsy. The aim of this study was to evaluate learning skills and academic performance in children and adolescents with absence epilepsy.

METHODS

Observational case-control study. Cases were chosen from the Central League against Epilepsy's clinic in Bogotá, Colombia. Controls were selected from a private school and matched with cases by age, school year, and sex. Medical history, seizure frequency, antiepileptic treatment, and academic performance were assessed. Academic abilities were tested with Batería de Aptitudes Diferenciales y Generales (BADyG) (a Spanish-language test of differential and general aptitudes). Data were analysed using Student t-test.

RESULTS

The sample consisted of 19 cases and 19 controls aged between 7 and 16. In 15 patients, seizures were controlled; all patients had received antiepileptic medication at some point and 78.9% were actively being treated. Although cases had higher rates of academic failure, a greater incidence of grade retention, and more therapeutic interventions than controls, these differences were not significant. Similarly, there were no significant differences on the BADyG test, except for the immediate memory subcategory on which cases scored higher than controls (P=.0006).

CONCLUSION

Children treated pharmacologically for absence epilepsy, whose seizures are controlled, have normal academic abilities and skills for their age.