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

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.