Morquio Syndrome, Types A and B (MPS IVA and B),
Enzyme Analysis
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.
Urinary excretion of keratan sulfate is seen
which can be assessed via
mucopolysaccharide electrophoresis.
Morquio, Types A and B can have significant
clinical overlap, thus enzyme analysis is necessary to distinguish between the
two types. Morquio, Type A is caused by deficiency of N acetyl
galactosamine-6-sulfatase. Morquio, Type B is caused by a deficiency of beta
galactosidase. 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.
Specimen requirements:
Enzyme activity can be measured in leukocytes or cultured fibroblasts.
Transport:
Please contact the laboratory before transporting tissue for enzyme assay. Fresh
tissue for culture should be sent by courier or 24-hour delivery. Blood should
be collected in a sodium heparin tube and shipped overnight.
Standard of analysis:
Assays will employ a 4-methylumbelliferyl substrate.
Time required:
Most assays will be complete in one week; assays of cultured cells may take 3-4
weeks.
Special requests:
Any type of special request must be made directly with the laboratory.
Report:
Written reports with interpretation are mailed to the referring physician.
Abnormal results will also be telephoned to the referring physician.
CPT Code:
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