ASD: Autism Spectrum Disorder; AT: Autoimmune Thyroiditis; MTHFR: Methylenetetrahydrafolatreductase; TCN1: Transcobalamin 1; TCN2: Transcobalamin 2; MTRR: Methionine synthase reductase; PEMT: Phosphoethanolamine N-Methyltransferase. The gene discussed is TCN1; the disease is autism spectrum disorder.