Disorders of sulfur amino acid metabolism

Abstract

Several inherited defects are known in the conversion of the sulfur-containing amino acid methionine to cysteine and the ultimate oxidation of cysteine to inorganic sulfate (Fig. 21.1). Cystathionine β-synthase (CBS) deficiency is the most important. It is associated with severe abnormalities of four organs or organ systems: the eye (dislocation of the lens), the skeleton (dolichostenomelia and arachnodactyly), the vascular system (thromboembolism), and the central nervous system (mental retardation, cerebrovascular accidents). A low-methionine, high-cystine diet, pyridoxine, folate and betaine in various combinations, and antithrombotic treatment may halt the otherwise unfavourable course of the disease. Methionine S-adenosyltransferase deficiency and γ-cystathionase deficiency usually do not require treatment.