UC San Diego

Autism spectrum disorder (ASD) is a disorder that hinders the affected individual's language, social, and behavioral development. The causes and origins of ASD have been studied, yet there is no clear consensus. One hypothesis states that ASD is caused by digestive enzymes that escape out of the intestinal lumen due to leaky gut syndrome and enter into the bloodstream, eventually causing damage to the brain. In this study, I hypothesized that because of the protease activities from these digestive enzymes, urine samples from the High-Risk group contains smaller peptides than those of the Low-Risk group. I devised and tested a method to quantify urinary peptide content, and utilized the method to examine 22 samples in the Low-Risk category and 16 samples in the High-Risk category. The two categories demonstrated a statistically significant difference (p = 0.044) in their urinary peptide content, with the High-Risk category containing a higher number of peptides per protein than the Low-Risk. This result suggests the possibility that ASD is associated with proteolytic degradation and production of protein fragments. Further study of a larger number of samples, a more in-depth examination of the urinary peptides, and a consideration of the participants' diet phase are recommended