This study aimed to find the common inborn errors of metabolism in Iranian patients with autism spectrum disorder.

In this cross-sectional multicenter study, 105 children and adolescents with autism spectrum disorder from six centers in different cities of Iran were enrolled between August, 2019 and October, 2020. Metabolic screening, including measuring plasma levels of amino acids, acylcarnitines, creatine, and guanidinoacetate, and urinary levels of organic acids, purines, and pyrimidines was performed. Other data, including age, parental consanguinity, history of seizure, developmental mile-stones, and physical examination, were also recorded.

An inborn error of metabolism was found in 13 (12.4%) patients. Five patients (4.8%) had cerebral creatine deficiency syndrome, 4 (3.8%) had arginine succinate aciduria, 2-methylbutyryl glycinuria, short-chain acyl-CoA dehydrogenase deficiency, and combined methylmalonic aciduria/malonic aciduria. There was a strong association between positive metabolic evaluation and parental consanguinity, history of seizures, microcephaly, and delayed development.

Our results suggest that metabolic screening should be performed in the cases of autism associated with parental consanguinity, developmental delay, and a history of seizures. The assays to be considered as a screening panel include plasma or blood amino acids, acylcarnitines, creatine and guanidinoacetate, and urinary levels of organic acids.