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Diagnostic Services

Genetics Lab


Neuronal Ceroid Lipofuscinosis - CLN 1 (PPT) enzyme

The neuronal ceroid lipofuscinoses (NCL) are a group of neurodegenerative disorders, inherited in an autosomal recessive manner. There are 8 genes (CLN 1-8), which have several identified mutations associated with NCL. The genes most commonly affected in pediatric patients are CLN 1, 2 and 3.

Palmitoyl-protein thioesterase (PPT) deficiency, caused by mutations in the CLN1 gene is responsible for 100% of cases of infantile onset (INCL), 8% of classic late-infantile onset (cLINCL), 21% of cases of juvenile (JNCL) and an unknown, but likely small percentage of adult (ANCL) neuronal ceroid lipofuscinosis.

Test Name: Ceroid Lipofuscinosis - CLN 1 (palmitoyl-protein thioesterase)
Test Code:
Test Description:
Enzymatic rate reaction of the PPT enzyme in blood, dried blood spots, cultured fibroblasts, or cultured fetal cells (CVS or amnio).
PPT, NCL, CLN 1, Batten disease; PPT deficiency
This test is used to diagnose NCL due to PPT deficiency in a symptomatic individual, primarily the infantile-onset form. This test can be used for prenatal diagnosis but is NOT used for carrier testing.
Related Tests: Maternal Cell Contamination - Biochemical Tests  
Maternal DNA is compared to fetal DNA to evaluate whether maternal cell contamination of the fetal sample has occurred.

Ceroid Lipofuscinosis - CLN 2 (tripeptidyl peptidase)  
This test is used to diagnose NCL due to TPP deficiency in a symptomatic individual, primarily the classic late-infantile onset form.

Clinical Links: Neuronal Ceroid Lipofuscinoses Gene Review
Performed weekly
Turnaround Time:
7-10 days
Fluorometric enzyme assay
Reference Range:
Interpretive report provided
Consent Form:
Sample Requirements: Type
Whole blood: 10 ml ACD (yellow)
Dried Blood Spots: 3 filled spots on filter paper (newborn screening card)
Fibroblasts/fetal cells: 2 T-25 flasks
Skin biopsy: 2-4mm skin punch biopsy

Do NOT spin or freeze blood. Keep room temperature.

Room temperature. Blood should be received within 24 hrs of collection. If shipping will be delayed, consider submitting blood spots. Cultured cells/skin biopsy samples should be submitted in appropriate cell culture/transport media.
Samples Received:
Mon - Fri 8:00am - 5:00 pm PST For Thurs shipping please specify Friday MORNING delivery
Special Considerations:
If fresh skin biopsy is submitted, Fibroblast Cell Culture (CH-SKIN) must be ordered separately. Please call to discuss. For prenatal samples, maternal cell contamination testing is required (ordered separately).
Please e-mail Client Services or call at 206-987-2617 with any billing questions
CPT Code:
Please e-mail Client Services or call at 206-987-2617 with any billing questions