In a recent study, 87/87 autistic individuals showed decreased metabolism of L-tryptophan, an amino acid that has a variety of impacts on brain development, compared to 0/128 individuals in the control group. User AutismScienceFdn, in the Autism subreddit, 11 Jun 2013
Decreased tryptophan metabolism in patients with autism spectrum disorders User WookieeWookiee, in the Reddit Science subreddit, 09 Jun 2013