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Test Code TPP I Tripeptidyl Peptidase I 

Clinical System Name

Tripeptidyl Peptidase I 

Synonyms

NCL

TPP

Neuronal ceroid lipofuscinoses

CLN2

Description

Fluorometric enzyme assay for tripeptidyl peptidase

Sample Requirements

Specimen: Whole Blood

Container(s): Yellow/ACD A or B, Dark Green/Sodium Heparin Tube

Preferred Vol:10.0 mL

Minimum Vol: 6.0 mL

 

Note: Sample must be processed within 24 hours.

Also acceptable: Dried blood spots; 2 full circles on a newborn screening card or cultured cells from skin fibroblasts (2 confluent T-25 flasks).

 

Processing Instructions

Reject due to:

Spin: N

Aliquot:N

Temp:RT

Storage location: Biochemical Genetics Box- RT

Weekend Processing: Contact Chem West (x72565) on dayshift. If Chemistry team is unavailable, sample should be stored in RT Biochemical Genetics box.

 

Off-site collection: Do not spin!  Keep at room temperature.  Transport Mon-Thurs at room temperature via overnight shipping.

Stability

Specimen Type Temperature Time
whole blood Room temp

≤24 hr

whole blood Refrigerated <24 hr

 

Availability

STAT Performed TAT
N Weekly 7-10 days

 

Contact the Biochemical Genetics Lab for requests outside of stated availability (206)987-2216.

Performing Laboratory

Seattle Children's Laboratory    

Department

Department:  Biochemical Genetics

Phone Number: 206-987-2216

 

Reference Range

 

Specimen Type Normal Range

WBC

70-300  nmol/hr/mg protein
Blood Spots 30-220 nmol/hr/spot

 

Methodology

Method: Fluorometric Enzyme assay

Analytical Volume:

Limitations:

CPT Codes

82657

Special Instructions

Links to:

Consent Forms

Algorithms

Requisition

Biochemical Genetics Requisition

 

On the requisition include clinical information needed for appropriate interpretation. (Age, gender, drug therapy and family history)

Clinical Utility

About 80% of patients with late infantile NCL and 7% of pateints with juvenile onset NCL have a deficiency of the lysosomal enzyme tripeptidyl peptidase 1 (TPP1). Disease is characterized by seizures, ataxia, myoclonus, psychomotor retardation, vision loss and speech impairment.