To the Editor:—
In previous communications (Lancet1:1191,1965; New Eng J Med273:1356, 1965) we reported diminished levels of whole blood serotonin and significantly increased levels of leukocyte, erythrocyte, and whole blood galactose1-phosphate-uridylyltransferase, leukocyte acid and alkaline phosphatases, erythrocyte glucose-6-phosphate dehydrogenase and leukocyte-5-nucleotidase in patients with trisomic mongolism. Normal values were found in the translocation type of mongolism (Down's syndrome).Further studies of the same group of 12 trisomic and 12 translocation mongols matched by age and sex with 12 healthy controls are the subject of the present report. The selection of patients, materials, and chemical methods used have been previously described.Plasma hydroxyproline was measured by the method of LeRoy et al1 and the following five plasma enzymes were assayed according to Sigma2: leucine aminopeptidase, fructose aldolase, isocitric dehydrogenase, glutamic pyruvic transaminase, and creatine phosphokinase.
The results are summarized in the Table. Plasma leucine