Researchers at the JC Self Research Institute of the Greenwood Genetic Center (GGC) have reported an exciting new finding that may allow for earlier diagnosis of individuals with autism spectrum disorders (ASDs), as well as a clearer understanding of the disorder.
Their study found that individuals with ASDs showed significantly decreased metabolism of the amino acid L-tryptophan when compared to normally developing persons, as well as individuals with other neurodevelopmental disorders. Decreased metabolism suggests there is a delay in the processing of this amino acid.
L-tryptophan is an amino acid used by cells to make protein. The body cannot produce L-tryptophan, therefore it must be obtained from the diet. Common sources include chicken, tuna, and turkey. This amino acid plays a significant role in brain development and function. L-tryptophan serves as a critical precursor for several critical neurochemical reactions in the body. For example, L- trpotophan stimulates the release and production of serotonin and melatonin. Abnormalities in the production of serotonin and melatonin have been linked to behavioral and neurodevelopmental problems (Sandyk, 1992).
Researchers also measured the expression of genes known to be involved in metabolizing L-tryptophan. Patients with autism expressed some of these genes at lower levels as well.
Currently, ASD diagnosis depends upon a variety of assessments, including developmental evaluation and parental interviews. The average age of diagnosis is 4.5 years of age, yet symptoms may appear as early as 18 months. No diagnostic blood tests exist to accurately diagnose ASDs.
Researchers at GGC are hopeful that their finding may lead to the development of an earlier blood-screening test for autism. A blood test that identifies low levels of L-tryptophan may allow doctors to identify metabolic deficits in the brain. In other words, the test would examine the gene’s expression in attempt to distinguish between children with and without ASDs.
SynapDx, a laboratory services company, is funding the study in hopes of developing and marketing the blood test. SynapDx completed a study in 2012 using an in-house developed blood test as a means of autism diagnosis. The study blindly compared 170 children with ASDs and 115 without. The blood test correctly identified the children two-thirds of the time. This trial’s success has led the company to continue conducting further studies in hopes of validating the development.
The release of a screening test could validate doctors’ clinical evaluations and diagnosis of ASDs. While a blood test may not offer sufficient evidence to diagnose ASD independently, it will certainly decrease the amount of time of needed to confirm a diagnosis. Using a clinically significant blood test in conjunction with patient evaluations will increase the validity and objective nature of a diagnosis.
An earlier diagnosis will allow for more effective and timely therapies for affected children and families. Speeding up the diagnostic process will grant families access to treatments earlier, allowing for better results. The National Institute of Health has granted additional funding to GGC’s autism research in hopes of turning this recent finding into a simple blood test for autism.
In addition, this information helps researchers to better understand a possible biochemical mechanism behind ASDs. These findings provide evidence that the disorder may be related to the metabolic pathways involving L-tryptophan. This finding allows will researchers to further focus on the exact point that the disruption is occurring.
Important discoveries such as these bring research organizations one step closer to improved ASD diagnosis and therapy. To read more about this study, click here.
Because clinical and neurobiological research is constantly advancing, staying up to speed with groundbreaking research can be extremely overwhelming for families. However, The Autism Research Foundation (TARF) believes staying informed is key to promoting awareness and a better understanding of autism. TARF hopes to assist you in keeping up with the latest research by updating this blog on a regular basis, as well as hosting the Current Trends in Autism Research Conference.
Boccuto, Luigi, Chin-Fu Chen, Ayla Pittman, Cindy Skinner, Heather McCartney, Kelly Jones, Barry Bochner, Roger Stevenson, and Charles Schwartz. “Decreased Tryptophan Metabolism in Patients with Autism Spectrum Disorders.” Molecular Autism 16 (2013): 4-16.
Greenwood Genetic Center. Advancement Paves Way for Early Blood Test and Therapeutic Options. Greenwood Genetics – GGC Reports Autism Discovery. 5 June 2013. Web.
Sandyk, R. “L-tryptophan in Neuropsychiatric Disorders: A Review.” International Journal of Neuroscience (1992): 127-44.