title: A review of the clinical presentation and laboratory findings in two uncommon hereditary disorders of sulfur amino acid metabolism, beta-mercaptolactate cysteine disulfideuria and sulfite oxidase deficiency.
abstract: Two hereditary disorders of sulfur amino acid metabolism, beta-mercaptolactate-cysteine disulfideuria and sulfite oxidase deficiency, were described twenty years ago. Other examples of these disorders have been limited to about 5 of each in the world literature since then. Reasons for the apparent rarity of these conditions are discussed and the analytical procedures to identify them are reviewed. The detection of the first depends on the positive result of a cyanide-nitroprusside test followed by positive identification of the specific mixed disulfide. The enzyme mercaptopyruvate sulfur transferase has been shown to be deficient. In the second disorder of sulfite oxidase deficiency, the clinical presentation with progressive dystonia and dislocated lenses in an infant should suggest further laboratory investigations for this disorder which would not be detected by conventional laboratory screening procedures. Laboratory diagnosis can be obtained by use of the Merckoquant sulfite test on a fresh urine sample. Quantitative thiosulfate and taurine measurements can also be made. Positive identification of the specific amino acid S-sulfo-L-cysteine should also be made. The enzyme sulfite oxidase is missing from such organs as liver, kidney and brain. This latter condition may also be associated with xanthinuria. For this combined disorder of sulfite oxidase and xanthine oxidase, a deficiency of a molybdenum-containing cofactor has been demonstrated.
mesh_terms: D000293:Adolescent; D000328:Adult; D000592:Amino Acid Metabolism, Inborn Errors / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D003545:Cysteine / Q000031:analogs & derivatives* / Q000652:urine; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010088:Oxidoreductases / Q000172:deficiency*; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000172:deficiency*; D014969:Xanthine Oxidase / Q000172:deficiency
chemical_list: C001705:beta-mercaptolactate cysteine disulfide; D010088:Oxidoreductases; D014969:Xanthine Oxidase; D050862:Oxidoreductases Acting on Sulfur Group Donors; D003545:Cysteine