Glycogen Storage Disease Type II, Pompe disease : Glucose Tetrasaccharide (Glc4) Monitoring

Test Information

Pompe disease is caused by a deficiency of the enzyme alpha-glucosidase (GAA), an enzyme that at normal levels will break down glycogen in the body. Infantile-onset Pompe disease is characterized by hypotonia, generalized muscle weakness and hypertrophic cardiomyopathy. Death generally occurs within the first year of life due to cardiac and respiratory failure. The later-onset form shows greater variability with a slowly progressive muscle weakness and respiratory insufficiency. The degree of enzyme deficiency is generally related to the severity and age of onset. Glucose tetrasaccharide, also known as Glc4 or Hex4, is used as a biomarker to evaluate the clearance of glycogen from cells. Analysis of glucose tetrasaccharide in urine can be used to monitor the effectiveness of enzyme replacement therapy.

Turnaround Time

10 days

CPT Code(s)

82570 & 83789

Cost

$202

Clinical Information

Pompe disease is caused by a deficiency of the enzyme alpha-glucosidase (GAA), an enzyme that at normal levels will breakdown glycogen in the body. Infantile-onset Pompe disease is characterized by hypotonia, generalized muscle weakness and hypertrophic cardiomyopathy. Death generally occurs within the first year of life due to cardiac and respiratory failure. The later-onset form shows greater variability with a slowly progressive muscle weakness and respiratory insufficiency. The degree of enzyme deficiency is generally related to the severity and age of onset.

Indications

Biomarker analysis of Glc4 can be used to monitor disease progression for affected individuals including those receiving enzyme replacement therapy.

Methodology

Liquid chromatography-tandem mass spectrometry.

Specimen Requirements

At least 3 ml of a random catch sample of urine is needed for Pompe disease monitoring.

Transport Instructions

Urine samples should be frozen after collection. Samples must be sent frozen via overnight delivery or courier, preferably on dry ice.

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

Analyte Analysis, Analytes and Biomarkers, Biochemical Testing
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...

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