Sialidosis : alpha-neuraminidase-sialidase Enzyme Analysis

Test Information

This biochemical test is a quantitative measurement of  of alpha-neuraminidase-sialidase enzyme activity and can be used as a 1st tier test for patients with a clinical suspicion of sialidosis. Demonstration of deficient alpha-neuraminidase-sialidase enzyme activity is considered the gold standard to confirm a diagnosis of sialidosis, or mucolipidosis type I.

In addition, this assay can be used to clarify molecular findings in the NEU1 gene.

Turnaround Time

2 weeks

CPT Code(s)

82657

Cost

$200


Enzymes

alpha-neuraminidase-sialidase

Clinical Information

Sialidosis, also known as mucolipidosis type I, is among the rarest Lysosomal Storage Disorder (LSD) classified as part of the glycoproteinoses. There are two clinically distinct sub-types of sialidosis, type I and type II.

The less severe form of the disorder, sialidosis type I, characterized by later onset, cherry red spots, progressive vision loss. These patients can also have other neurological symptoms such as ataxia and myoclonus, but typically have normal intelligence.

Type II is the more severe form of sialidosis. These patients usually have more physical findings than patients with type I, such as short stature, coarse features, thoracic kyphosis, and hepatosplenomegaly. Similar to the milder type I patients, individuals with type II may also have the cherry red spot, ataxia, and myoclonus. However, additional neurological symptoms are likely to be present in patients with type II.

Methodology

4-methylumbelliferyl substrate

Specimen Requirements

Enzyme activity can only be measured in cultured fibroblasts. The lab will accept a tissue sample or cultured flasks of cells. A punch skin biopsy should collected and placed in sterile media or saline. Do NOT place tissue in formalin or formaldehyde. Do not freeze tissue. If sending cultured cells, send 2x T25 flasks.

Transport Instructions

Fresh tissue or cultured fibroblasts can be sent overnight at room 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
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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