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- General: Mucopolysaccharidosis may be suspected after a thorough physical examination. Common physical symptoms may include thickened lips and skin, enlarged tongue and mouth, abnormal bone size and shape, and short stature. An elevated level of glycosaminoglycans may also be detected in the urine indicating mucopolysaccharidosis. A urine test does not distinguish between the different types of mucopolysaccharidosis.
- DNA testing: DNA testing may be performed to confirm and classify mucopolysaccharidosis. Each type of MPS has a known mutation that is specific to the type of disease. In cases of a family history of MPS, genetic testing may also be used to identify a carrier. If MPS is suspected, a cytogenetic test may be performed to confirm a diagnosis. A sample of the patient's blood is taken and analyzed in a laboratory for a defect in any of the 11 enzymes involved in the breakdown of glycosaminoglycans. The 11 enzymes that may be affected in MPS are alpha-L-iduronidase, iduronate sulfatase, alpha-N-acetylglucosaminidase, heparan N-sulfatase, acetyl-CoA alpha-glucosaminide acetyltransferase, acetylglucosamine 6-sulfatase, acetylgalactosamine 6-sulfatase, beta-galactosidase, N-acetylgalactosamine 4-sulfatase, beta-glucuronidase, and hyaluronidase.
- Enzyme testing: An enzyme assay may be used to make a definitive diagnosis of the type of MPS based upon the levels of the 11 enzymes involved in glycosaminoglycan breakdown. Enzyme activity is measured from a tissue or blood sample of leukocytes, fibroblasts, or serum that is combined with a substrate that is particular to the target enzyme. The target enzyme can be alpha-L-iduronidase, iduronate sulfatase, alpha-N-acetylglucosaminidase, heparan N-sulfatase, acetyl-CoA alpha-glucosaminide acetyltransferase, acetylglucosamine 6-sulfatase, acetylgalactosamine 6-sulfatase, beta-galactosidase, N-acetylgalactosamine 4-sulfatase, beta-glucuronidase, or hyaluronidase.
- Prenatal testing: If there is a family history of MPS, prenatal testing may be performed to determine if the fetus has the disorder. Amniocentesis and chorionic villus sampling (CVS) can diagnose MPS. However, because there are serious risks associated with these tests, patients should discuss the potential health benefits and risks associated with these procedures with a medical professional and/or genetic counselor.
- During amniocentesis, a long, thin needle is inserted through the abdominal wall into the uterus and a small amount of amniotic fluid is removed from the sac surrounding the fetus. Cells in the fluid are then analyzed for normal and abnormal chromosomes. This test is performed after 15 weeks of pregnancy. The risk of miscarriage is about one in 200 to 400 patients. Some patients may experience minor complications, such as cramping, leaking fluid, or irritation where the needle was inserted.
- During CVS, a small piece of tissue (chorionic villi) is removed from the placenta between the ninth and 14th week of pregnancy. CVS may be performed through the cervix or through the abdomen. The cells in the tissue sample are then analyzed for the mutations responsible for MPS. Miscarriage occurs in about 0.5% to 1% of women who undergo this procedure.
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