Iduronate sulfatase deficiency

The mucopolysaccharidoses are classified into seven clinical types and all are transmitted by autosomal recessive inheritance except for Hunter syndrome (MPS II, iduronate sulfatase deficiency), which is an X-linked disorder. Diagnosis of the specific disorder is made by measuring the specific enzyme activities in leukocytes or cultured skin fibroblasts. Because it takes some time... 

Hunter syndrome (MPS-II) is an X-linked disorder arising from deficiency of iduronate sulfatase,... 

Idursulfase (Elaprase) is a drug used to treat mucopolysaccharidosis II or Hunter syndrome. It is a lysosomal storage disease caused by iduronate-2-sulfatase deficiency. Idursulfase is a purified form of iduronate-2-sulfatase produced by recombinant DNA technology in a human cell line. The drug provides clinically important benefits to Hunter syndrome patients. After intravenous infusion Idursulfase is eliminated by peptide hydrolysis with an elimination half-life of 45 minutes. The most common adverse events are hypersensitivity reactions, pyrexia, headache and arthralgia. 

Sulfotransferases917 920a transfer sulfo groups to O and N atoms of suitable acceptors (reaction type ID, Table 10-1). Usually, transfer is from the "active sulfate," 3 -phosphoadenosine 5 -phosphosuIfate (PAPS),921 whose formation is depicted in Eq. 17-38. Sulfatases catalyze hydrolysis of sulfate esters. The importance of such enzymes is demonstrated by the genetic mucopolysaccharidoses. In four of these disease-specific sulfatases that act on iduronate sulfate, heparan N-sulfate, galactose-6-sulfate, or N-acetylglu-cosamine-4-sulfate are absent. Some of these, such as heparan N-sulfatase deficiency, lead to severe mental retardation, some cause serious skeletal abnormalities, while others are mild in their effects.922... 

B. All of the mucopolysaccharidoses are transmitted by autosomal recessive inheritance except Hunter syndrome (MPS II), a deficiency in iduronate sulfatase that is X-linked recessive. Since Hunter syndrome is X-linked, it is almost exclusively seen in males. Since our patient is female, she would not be expected to have an X-linked disorder. 

E. Since this patient is suspected of having Hunter syndrome, a deficiency in iduronate sulfatase, iduronate 2-sulfate would be expected to be present at the nonreducing end of glycosaminoglycans found in this patient s urine. A deficiency of iduronate sulfatase would prevent the sulfate ester bond of iduronate 2-sulfate residues from being hydrolyzed and further degradation of the glycosaminoglycan would be halted. 

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