The plasma level of glutamic acid decarboxylase 65 (GAD65) increased in severely autistic Iranian children.

Introduction: Autism spectrum disorder (ASD) is a neurodevelopmental disorder. The major etiological mechanism lies in glutamatergic/GABAergic imbalance. The aim of this study was to evaluate the plasma levels of glutamic acid decarboxylase 65 (GAD65) protein in mildly and severely autistic patients, and also to compare plasma GAD65 concentration in mild and severe autism.

Method: In total, 62 autistic patients (aged 6-9 years) and 17 age-matched neurotypically healthy controls were included in the study. The diagnosis, as well as the level of autism, was assessed by applying the Gilliam Autism Rating Scale. Plasma GAD65 protein level was determined using an enzyme-linked immunosorbent assay (ELISA) kit for GAD65.

Results: Our findings showed no remarkable alteration in plasma GAD65 concentration in patients with mild autism as compared to healthy subjects, while patients with severe autism showed an increased plasma level of GAD65 as compared to healthy controls and mildly autistic patients.

Conclusion: Our findings suggest the level of plasma GAD65 to be considered a potential diagnostic biomarker for the severity of autism (Fig. 2, Ref. 40).