GM1 Gangliosidosis – Enzyme Analysis

Disease name GM1 Gangliosidosis
Enzyme Name Beta-galactosidase
Clinical info

GM1 gangliosidosis is an autosomal recessive lysosomal storage disease with 3 clinical subtypes characterized by varying severity and age of onset. The primary features are neurodegeneration and skeletal abnormalities.

The classic or infantile type is most common and is usually present at birth. Coarse features, edema, failure to thrive, hypotonia and hepatomegaly are all characteristic findings. There is usually rapid progression of symptoms with the development of spasticity, seizures and general neurologic deterioration with death typically occurring by age 2.

Progressive cerebral deterioration is characteristic of the late infantile/juvenile form of GM1 gangliosidosis as well. However, symptoms usually start around 1 year with regression of gained skills such as speech and walking. Seizure management is often a major issue and these patients usually die between ages 3 and 7.

The chronic/adult subtype of GM1 is the least common subtype with the phenotype consisting of dystonia, progressive ataxia and cerebellar dysarthria. These patients do not have the typical dysmorphic facies.

Indications This test can be used to confirm a suspected GM1 gangliosidosis diagnosis. Prenatal diagnosis and carrier testing via enzyme analysis are not available.
Associated Tests

Measurement of beta-galactosidase is included in the Lysosomal Enzyme Panel, the Dried Blood Spot Lysosomal Panel, the Hydrops Panel, the Neurological Panel, and the Oligosaccharidoses Panel
Molecular analysis of the gene for GM1 gangliosidosis (GLB1) is also available for identification of the causative mutation within a family, carrier status and prenatal diagnosis.

Methodology Quantifies level of alpha-fucosidase via the 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 needs 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.

Dried Blood Spot Sample Collection and Requirements

In addition, a dried blood spot or blood drawn in an EDTA tube can be used for GM1 Gangliosidosis molecular analysis and may be sent for DNA banking. Please indicate on the requisition if DNA should be banked for follow-up molecular testing.

Transport

Whole blood samples (for leukocyte analysis) should be shipped at ambient temperature and must arrive at the laboratory within 24 hours of blood draw.

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 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 82657
Cost $200
Contact For further information contact one of our This email address is being protected from spambots. You need JavaScript enabled to view it. at 1-800-473-9411.

Molecular Diagnostic Lab

The Molecular Diagnostic Lab offers DNA analysis for many genetic disorders via gene sequencing, targeted mutation analysis, MLPA deletion/duplication testing, trinucleotide repeat analysis and next generation sequencing panels.

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