Abstract text

A method for confirming a diagnosis of autism in of an individual comprises obtaining a sample of feces from an individual, determining a quantitative level of chymotrypsin present in the sample, and comparing the quantitative level of fecal chymotrypsin in the stool sample of the person having autism to a stool sample from an individual that has a normal fecal chymotrypsin level and does not have autism and confirming a diagnosis of autism based on the measurement of the quantitative level of fecal chymoptrypsin.