Increased concentrations of various amino acids in schizophrenic patients. Evidence for heterozygosity effects?

The hypothesis is examined that heterozygosity for amino acid disorders (AAD) is a genetic component of susceptibility for schizophrenic psychoses. To detect possible heterozygotes, urinary and blood amino acid levels were analyzed in a sample of subjects with a diagnosis of schizophrenia and in their biological parents and compared with those of a sample of healthy volunteers. The results showed increased blood and urinary levels of certain amino acid in those patients who have at least one parent with the same amino acid abnormality. This finding points to the possibility of heterozygosity for AAD in schizophrenic patients.