Autism Studies and Related Medical Conditions, January 2009 - TACA

As with energy requirements, protein requirements are relatively much greater in
infants and decline progressively with age. Amino acid metabolism in pediatric
patients is characterized by the following differences. The requirement for
essential amino acids in neonates is larger than that in adults. Because of low
activity of phenylalanine hydroxylase and cystathionase, hyperphenylalaninemia
and hypermethioninemia tend to occur, whereas tyrosine and cysteine tend to be
deficient. In addition to cysteine and tyrosine, histidine, lysine, arginine and
taurine are considered as semiessential amino acids. Nowadays there are
different kinds of amino acid formulas to satisfy these specific requirements, and
most of these formulas are intended to normalize the plasma aminogram.
However, the nutritional benefit of these formulas for growth and development is
still not completely proven, and the pharmacological use for specific diseases is
expected with some modification of these formulas.
PMID: 9437700 [PubMed - indexed for MEDLINE]
James SJ, Cutler P, Melnyk S, Jernigan S, Janak L, Gaylor DW, Neubrander JA.
Metabolic biomarkers of increased oxidative stress and impaired methylation capacity in
children with autism. Am J Clin Nutr. 2004 Dec;80(6):1611-7.
Department of Pediatrics, University of Arkansas for Medical Sciences, and the
Arkansas Children's Hospital Research Institute, Little Rock, AR 72202, USA.
jamesjill@uams.edu
BACKGROUND: Autism is a complex neurodevelopmental disorder that usually
presents in early childhood and that is thought to be influenced by genetic and
environmental factors. Although abnormal metabolism of methionine and
homocysteine has been associated with other neurologic diseases, these
pathways have not been evaluated in persons with autism. OBJECTIVE: The
purpose of this study was to evaluate plasma concentrations of metabolites in
the methionine transmethylation and transsulfuration pathways in children
diagnosed with autism. DESIGN: Plasma concentrations of methionine, S-
adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), adenosine,
homocysteine, cystathionine, cysteine, and oxidized and reduced glutathione
were measured in 20 children with autism and in 33 control children. On the
basis of the abnormal metabolic profile, a targeted nutritional intervention trial
with folinic acid, betaine, and methylcobalamin was initiated in a subset of the
autistic children. RESULTS: Relative to the control children, the children with
autism had significantly lower baseline plasma concentrations of methionine,
SAM, homocysteine, cystathionine, cysteine, and total glutathione and
significantly higher concentrations of SAH, adenosine, and oxidized glutathione.
This metabolic profile is consistent with impaired capacity for methylation
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