Central tetrahydrobiopterin concentration in neurodevelopmental disorders.

Hmmm, I would say considering that Nrf2 helps to maintain coupling of NO via tetrahydrobiopterin....the resources of methionine, proper functionings of the pathway and methylation status of the pathways involved may throw a really big wrench into things....and could account for a number of conditions including those in autism and other environmental illnesses including multiple chemical sensitivity or idiopathic intolerance.

"citrulline-to-methionine was found to correlate with the cerebrospinal fluid BH(4) concentration (r = -0.67, p < 0.05). Both citrulline and methionine are substrates in inflammation and oxidative stress pathways - two pathways that utilize BH(4) and are abnormally activated in autism. These data suggests that central BH(4) concentration may be related to systemic inflammation and oxidative stress pathways."

Read more: CiteULike: Central tetrahydrobiopterin concentration in neurodevelopmental disorders.:

Further Reading:

• Dysfunction of Methylation and Nrf2 in Environmental Illness-  
  Is This A Better Explanation than NO/ONOO- ?
  
  

Additional Citation:

• Frye, R. E., Huffman, L. C., and Elliott, G. R. (2010). Tetrahydrobiopterin as a novel therapeutic intervention for autism. Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics, 7(3):241-249.
  http://www.citeulike.org/user/HEIRS/article/7557630