Neuronal Ceroid Lipofuscinosis Type 2 (CLN2) : Tripeptidyl peptidase 1 Enzyme Analysis

Test Information

This biochemical test is a quantitative measurement of tripeptidyl peptidase 1 enzyme activity and can be used as a 1st tier test for patients with a clinical suspicion of Neuronal Ceroid Lipofuscinosis Type 2 (CLN2). Demonstration of deficient tripeptidyl peptidase 1 enzyme activity is considered the gold standard to confirm a diagnosis of Neuronal Ceroid Lipofuscinosis Type 2 (CLN2).

In addition, it can be used to clarify molecular findings in the TPP1 gene and to monitor patients undergoing treatment.

Turnaround Time

2 weeks

CPT Code(s)

82657

Cost

$200


Enzymes

Tripeptidyl peptidase 1

Clinical Information

The neuronal ceroid lipofuscinoses (CLN) are a group of conditions that are inherited in an autosomal recessive pattern. CLN1 is characterized by progressive microcephaly, contractures, developmental delay, psychiatric symptoms, and neurological degeneration including seizures and ataxia. Retinal and macular degeneration leads to blindness by the age of 2 years with diminished or abolished ERG results. Age of onset varies with infantile, late-infantile, juvenile and adult-onset forms of the disease with younger ages of onset typically associated with a more rapid progression of symptoms. The intracellular accumulation of lipopigments results in a characteristic microscopic pattern called granular osmiophilic deposits (GROD).

Indications

This test can be used to confirm a suspected neuronal ceroid lipofuscinosis 2 (CLN2) diagnosis.

Methodology

4-methylumbelliferyl substrate OR LC-MS/MS

Specimen Requirements

Enzyme activity can be measured in leukocytes. Send 5-7 ml of whole blood in a green top (sodium heparin) tube.

Transport Instructions

Whole blood should be sent over overnight at ambient temperature. Do not freeze whole blood. Samples for enzyme analysis must arrive to the lab within 24 hours of blood draw.

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
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