Morquio syndrome, Types A and B - Enzyme Analysis
|Disease name||Morquio syndrome, Types A and B (MPS IVA and B)|
|Enzyme Name||Morquio, Type A is caused by deficiency of N-acetyl-galactosamine-6-sulfatase.
Morquio, Type B is caused by a deficiency of beta galactosidase.
|Clinical info||Morquio syndrome is characterized by short stature and trunk, large head, mildly coarse facies, widely spaced teeth, corneal clouding, a bell-shaped chest, vertebral anomalies, joint stiffness and kyphoscoliosis. Other features may include inguinal hernia, hepatomegaly and hearing loss. There is a wide spectrum of those affected ranging from mild to severe. Intelligence is typically not affected.|
|Indications||Morquio, Types A and B can have significant clinical overlap, thus enzyme analysis is necessary to distinguish between the two types. These enzymes are needed for the modification and removal of keratin sulfate. Enzyme analysis for each type of Morquio syndrome may be ordered individually or as a panel. Prenatal diagnosis and carrier testing via enzyme analysis are not available.|
|Associated Tests||Urinary excretion of keratan sulfate is seen which can be assessed via MPS electrophoresis. Beta galactosidase is also on the hydrops enzyme panel.|
|Methodology||Assays employ a 4-methylumbelliferyl substrate.|
Morquio Enzyme Panel (MPS IVA & IVB): Enzyme activity of N-acetyl-galactosamine-6-sulfatase and beta galactosidase can be measured in leukocytes or cultured fibroblasts. For leukocytes, please send 5-10 ml of whole blood in a green top (sodium heparin) tube.
Morquio syndrome type B only: Dried blood spot enzyme analysis is available for beta galactosidase. A minimum of three circles need to be filled in. Each circle should contain one drop of blood (about 100 microliters). See the link below for additional sample collection and handling instructions.
In addition, a dried blood spot or blood drawn in an EDTA tube can be used for Morquio A or Morquio B molecular analysis and may be sent for DNA banking. Please indicate on the requisition if DNA should be banked for follow-up molecular testing.
Whole blood samples (for leukocyte analysis) should be shipped at ambient temperature and must arrive at the laboratory within 24 hours of specimen collection.
Cultured fibroblasts should be sent overnight at room temperature.
Morquio B ONLY: For a dried blood spot: When the sample has dried 3-4 hours, fold cover at score line, over sample, and tuck into flap. Samples should be placed in the mail within 24 hours of collection. Overnight shipping is preferred.
|Turnaround time||14 days
Cell culture can take 1-4 weeks and may lengthen turnaround time.
|CPT Codes||Single enzyme: 82657
Panel of Morquio A and B: 82657(x2)
Morquio Panel: $400 for both enzymes
Leukocytes or cultured fibroblasts: $200
The Biochemical Lab provides diagnostic and screening tests for a variety of inherited metabolic disorders.