Homocysteine Levels in Autism Spectrum Disorder: A Clinical Update

Background and Objective: Homocysteine (Hcy) is a non-protein alpha-amino acid, which plays several important roles in human physiology and in the central nervous system. Although Hcy has several known biological properties in one-carbon metabolism, its overproduction might be harmful, and could add to the pathophysiology associated with ASD. We reviewed the current evidence about changes in Hcy concentration in ASD and tried to correlate its changes with the clinical profile. Discussion: The concentration of the amino acid in biological fluids (blood and urine) in children/youngs with ASD is increased in the majority of studies when comparing to typically developing control subjects. Some report demonstrated a significant association between the severity of the disorder and the abnormalities in Hcy levels. Conclusion: Further research is needed to correlate the increase in Hcy with specific symptoms/deficits in ASD and to evaluate the clinical impact of strategies that can reduce Hcy concentration in ASD.