Plasma-CSF Glycine Ratio in Normal and Nonketotic Hyperglycinemic Subjects

Abstract

To the Editor: The report by Perry and his colleagues¹ on glycine metabolism in brain and cerebrospinal fluid of patients with various types of hyperglycinemia highlights an important general theme — namely, the relation of amino acid concentrations in cerebrospinal fluid to the metabolism of amino acids in brain.Cerebrospinal fluid is apparently cleared of amino acids by up-take on specific membrane transport systems at the brain-cerebrospinal-fluid interface.^{2 , 3} It is believed that amino acids appear in the fluid largely by efflux from brain.⁴ In this sense, filtration and reabsorption of amino acids in kidney are analogous to the flux of . . .