FOXP2 down expression is associated with executive dysfunctions and electrophysiological abnormalities of brain in Autism spectrum disorder; a neuroimaging genetic study

Bridging Genetic Insights with Neuroimaging in Autism Spectrum Disorder-A Systematic Review

Autism Spectrum Disorder (ASD) is an early onset neurodevelopmental disorder characterized by impaired social interaction and communication, and repetitive patterns of behavior. Family studies show that ASD is highly heritable, and hundreds of genes have previously been implicated in the disorder; however, the etiology is still not fully clear. Brain imaging and electroencephalography (EEG) are key techniques that study alterations in brain structure and function. Combined with genetic analysis, these techniques have the potential to help in the clarification of the neurobiological mechanisms contributing to ASD and help in defining novel therapeutic targets. To further understand what is known today regarding the impact of genetic variants in the brain alterations observed in individuals with ASD, a systematic review was carried out using Pubmed and EBSCO databases and following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. This review shows that specific genetic variants and altered patterns of gene expression in individuals with ASD may have an effect on brain circuits associated with face processing and social cognition, and contribute to excitation-inhibition imbalances and to anomalies in brain volumes.

Linked OXTR Variants Are Associated with Social Behavior Differences in Bonobos (Pan paniscus)

Single-nucleotide polymorphisms (SNPs) in forkhead box protein P2 (FOXP2) and oxytocin receptor (OXTR) genes have been associated with linguistic and social development in humans, as well as to symptom severity in autism spectrum disorder (ASD). Studying biobehavioral mechanisms in the species most closely related to humans can provide insights into the origins of human communication, and the impact of genetic variation on complex behavioral phenotypes. Here, we aimed to determine if bonobos (Pan paniscus) exhibit individual variation in FOXP2 and OXTR loci that have been associated with human social development and behavior. Although the ASD-related variants were reported in 13-41% of the human population, we did not find variation at these loci in our sample of 13 bonobos. However, we did identify a novel variant in bonobo FOXP2, as well as four novel variants in bonobo OXTR that were 17-184 base pairs from the human ASD variants. We also found the same linked, homozygous allelic combination across the 4 novel OXTR SNPs (homozygous TGTC) in 6 of the 13 bonobos, indicating that this combination may be under positive selection. When comparing the combined OXTR genotypes, we found significant group differences in social behavior; bonobos with zero copies of the TGTC combination were less social than bonobos with one copy of the TGTC combination. Taken together, our findings suggest that these OXTR variants may influence individual-level social behavior in bonobos and support the notion that linked genetic variants are promising risk factors for social communication deficits in humans.

Expression alteration of Neuroligin family gene in attention deficit and hyperactivity disorder and autism spectrum disorder

BACKGROUND

Autism spectrum disorder (ASD) is a complex neurodevelopment disorder with social and communicational deficiency, language impairment, and ritualistic behaviors. Attention deficit hyperactivity disorder (ADHD) is a pediatric psychiatric disorder with symptoms, including attention deficit, hyperactivity, and impulsiveness. ADHD is a childhood-onset disorder that can persist into adult life. Neuroligins are post-synaptic cell-adhesion molecules that connect neurons and have an essential role in the mediation of trans-synaptic signaling and shaping the synapse and circuits and neural network functioning.

AIMS

Present study aimed to shed light on the role of the Neuroligin gene family in ASD and ADHD.

METHODS AND PROCEDURES

mRNA levels of the Neuroligin gene family (NLGN1, NLGN2, NLGN3, and NLGN4X) were studied in the peripheral blood of 450 unrelated ASD patients, 450 unrelated ADHD patients, and the normal group included 490 unrelated non-psychiatric children by quantitative PCR. Also, clinical situations were considered.

OUTCOMES AND RESULTS

Results showed that mRNA levels of NLGN1, NLGN2, and NLGN3 were significantly down-regulated in the ASD group vs. control subjects. In ADHD, a significant reduction of NLGN2 and NLGN3 was detected in comparison with normal children. A comparison of ASD and ADHD subjects revealed that NLGN2 was significantly down-regulated in ASD subjects.

CONCLUSIONS

The Neuroligin family gene may play an essential role in the etiology of ASD and ADHD and thus be a source for a better understanding of neurodevelopment disorders.

IMPLICATIONS

Similar patterns of deficiency of Neuroligin family genes in ASDs and ADHDs may indicate the role of these genes in functions that have been affected in both disorders.

A Brief Overview of Neutrophils in Neurological Diseases

Neutrophils are the most abundant leukocyte in circulation and are the first line of defense after an infection or injury. Neutrophils have a broad spectrum of functions, including phagocytosis of microorganisms, the release of pro-inflammatory cytokines and chemokines, oxidative burst, and the formation of neutrophil extracellular traps. Traditionally, neutrophils were thought to be most important for acute inflammatory responses, with a short half-life and a more static response to infections and injury. However, this view has changed in recent years showing neutrophil heterogeneity and dynamics, indicating a much more regulated and flexible response. Here we will discuss the role of neutrophils in aging and neurological disorders; specifically, we focus on recent data indicating the impact of neutrophils in chronic inflammatory processes and their contribution to neurological diseases. Lastly, we aim to conclude that reactive neutrophils directly contribute to increased vascular inflammation and age-related diseases.