Dysregulation of the transsulfuration pathway has been implicated in autism with research showing homocysteine and and oxidized glutathione levels were significantly higher in children diagnosed with autism spectrum disorders while cysteine levels, total glutathione and glutathione were remarkably lower in childiren with autism spectrum disorder compared to control subjects. Homocysteine levels levels correlated significantly with increasing Childhood Autism Rating Scale scores.
Taurine is synthesized from l-cysteine. Taurine is involved in calcium homeostasis. Taurine levels in autistic children were lower than than in controls. There may be low taurine levels only in a subset of indivduals with autism. Not all studies show taurine levels are low in autism.
Research points to intracellular calcium homeostasis being dysregulated in autism. Genes for various sub-units of proteins that act as calcium channels are associated with autism. In autism dysregulation of the transsulfuration pathway could dysregulate taurine synthesis which could dysregulate calcium homeostasis.
Whatever the answer is increasing levels of L-cysteine through supplementing with L-cysteine containing amino acids is not the answer. L-cysteine containing amino acids can be very toxic.