Biochemical parameters in autism spectrum disorder: The search for new diagnostic markers

Aim: This study compares age and gender-matched control groups with cases aged 2-8 years diagnosed with autism spectrum disorder (ASD). With the obtained data, we aim to contribute to the elucidation of ASD's etiopathogenesis by providing the clinical use of laboratory parameters that can help with diagnosis and treatment monitoring. Material and Method: This study included 43 patients aged 2 to 8 years diagnosed with ASD and healthy controls matched for age and gender. Samples were analyzed using ELISA devices, biochemistry, and hemogram autoanalyzers. S Adenosyl Methionine (SAM), S-Adenosyl Homocysteine (SAH), Glycine N-methyl transferase, ALT, AST, Fe, UIBC, ferritin, folate, vitamin B12, TSH, T4, hemogram, Vitamin D, uric acid, insulin, glucose, total cholesterol, HDL, LDL, triglyceride, CRP, and creatinine levels were compared statistically. Results: No statistically significant difference was observed when comparing ALT, glucose, CRP, insulin, total cholesterol, HDL, LDL, triglyceride, creatinine, iron, UIBC, ferritin, folate, vitamin B12, TSH, T4, RBC, hemoglobin, hematocrit, MCV, and Glycine N-methyl Transferase levels (p>0.05). Wbc, platelet, uric acid, AST, vitamin D, and SAH levels were found to be significantly higher in the case group than in the control group. SAM and SAM/SAH levels were found to be significantly lower in the case group compared to the control group (p<0.05). In the ROC analysis, the diagnostic performance levels for SAM were calculated as the area under the curve of 0.876, the cut-off point was determined as 286.9 ng/mL, and the sensitivity was 85% and the specificity was 75%. The area under the curve for SAH was calculated as 0.671, the cut off point was determined as 0.49 ng/mL, and the sensitivity was 64% and the specificity was 64%. The area under the curve for the SAM/SAH ratio was calculated as 0.806, the cut-off point was determined as 576.3, and the sensitivity was 72% and the specificity was 72%. A significant and negative correlation was found between SAM and SAM/SAH ratios with the Modified Early Childhood Autism Screening Scale (M CHAT). As a result of the analysis, it was determined that a 1-unit increase in SAM value decreased the risk of autism 1/0.914 = 1.1 times, and a 1-unit increase in platelet increased the risk of autism 1.019 times. Conclusion: We believe that SAM, SAH levels, and SAM/SAH ratios can be introduced into clinical use as auxiliary biomarkers for current diagnostic methods. The relationship between the M-Chat total score, which is one of the scales used in ASD diagnosis, and these values further supports that these markers may be clinical biochemical laboratory parameters that can help with diagnosis. Keywords: Autism Spectrum Disorder (ASD), S-Adenosyl Methionine (SAM), S-Adenosyl Homocysteine (SAH), Glycine N-methyl Transferase, Biochemical Parameters