Mucopolysaccharidosis IVA (MPSIVA), Morquio syndrome A : N-acetyl-galactosamine-6-sulfatase Enzyme Analysis

Test Information

This is a quantification of enzyme activity. Demonstration of deficient enzyme activity is considered the gold standard to confirm the diagnosis.

Turnaround Time

2 weeks

CPT Code(s)

82657

Cost

$200.00


Enzymes

N-acetyl-galactosamine-6-sulfatase
Beta-galactosidase

Clinical Information

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.

Methodology

4-methylumbelliferyl substrate

Specimen Requirements

Enzyme activity can be measured in leukocytes, cultured fibroblasts, or dried blood spots. For leukocytes, please send 5-10 ml of whole blood in a green top (sodium heparin) tube. For dried blood spot collection, 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.

Transport Instructions

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.

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 can be mailed at ambient temperature.

Have Questions Need Support?

Call our laboratory at 1-800-473-9411 or contact one of our Laboratory Genetic Counselors for assistance.
Robin Fletcher, MS, CGC
Kellie Walden, MS, CGC

Biochemical Testing, Enzyme Analysis, Individual Enzyme Assays, Test Finder
Lucy's Story

Lucy's Story

When our daughter Lucy had a metabolic crisis at 7 days old, we were shocked and devastated to find out that she was born with a rare genetic disorder (MSUD). Her newborn screening results did not make it back in time to prevent the crisis, and no one at our local hospital was familiar with the disease. They did not know how to treat her. Calls were made to Greenwood Genetic Center to confirm her diagnosis...

In The News