Low Expression Levels of MAOA and TPH1 Genes May Represent Risk Factors in Boys With Autism Spectrum Disorder-A Case-Control Study.

Researchers studied blood samples from 30 boys with autism and 30 boys without autism. They found that boys with autism had lower levels of activity in two genes (MAOA and TPH1) that help make serotonin, a brain chemical important for mood and behavior. These lower gene activity levels might be risk factors that contribute to autism development, though they didn't relate to how severe the autism symptoms were.

This case-control study examined gene expression levels of MAOA and TPH1, key enzymes in serotonin metabolism, in 30 boys with autism spectrum disorder (ASD) compared to 30 typically developing controls. Using blood samples and quantitative PCR analysis, researchers found significantly reduced expression of both genes in the ASD group (p=0.017 for MAOA, p<0.001 for TPH1). No correlation was found between gene expression levels and autism severity within the ASD group. This is reportedly the first study to investigate these specific gene expressions in human blood samples for ASD, suggesting that disrupted serotonin pathway regulation through reduced MAOA and TPH1 expression may represent risk factors for ASD development in males.

Findings suggest serotonin pathway dysregulation may contribute to ASD risk in males. However, the clinical utility requires validation in larger, diverse populations. Results may inform future biomarker research and potential therapeutic targets involving serotonin metabolism, though direct clinical applications are premature.

Small sample size (30 per group), male-only population limits generalizability, case-control design cannot establish causation, single-center study, and no information provided about potential confounding variables or participant matching criteria.

It has been reported that disruptions in the metabolic pathways of tryptophan, the precursor of the neurotransmitter serotonin, may contribute to the development of autism spectrum disorder (ASD); however, further research is needed. Therefore, this study aims to assess the gene expression levels of two key enzymes involved in tryptophan metabolism, monoamine oxidase A (MAOA) and tryptophan hydroxylase-1 (TPH1), in male children diagnosed with ASD, and to explore their relationship with autism severity. For this purpose, 30 male children diagnosed with ASD according to the DSM-5 diagnostic criteria, who presented to the Institutional Child and Adolescent Psychiatry outpatient clinic, and 30 male children who presented to the same clinic with no psychiatric disorders detected were recruited as the control group. The subjects were administered the Childhood Autism Rating Scale.

The expressions of MAOA and TPH1 genes were determined using Quantitative Real-Time PCR. The expression levels of MAOA and TPH1 genes were significantly reduced in the patient group compared to the control group (p = 0.017 and 0.000, respectively). No statistically significant results were obtained between autism severity and the expression levels of these genes within the patient group (p > 0.05). This study is the first to investigate and establish a correlation between the expression levels of the MAOA and TPH1 genes and ASD using human blood samples.

Low MAOA and TPH1 gene expression levels, may contribute to serotonergic dysregulation potentially acting as risk factors involved in ASD.