MAG and autism: Children with ASD had significantly lower serum levels of 25‐hydroxy VitD than healthy children with 40 and 48% being VitD deficient and insufficient, respectively. Serum 25‐hydroxy VitD had significant negative correlations with Childhood Autism Rating Scale. Increased levels of serum anti‐MAG auto‐antibodies were found in 70% of children with ASD.