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Neuronal Ceroid-Lipofuscinosis 2 (CLN2)

The neuronal ceroid-lipofuscinoses are a group of inherited, neurodegenerative, lysosomal storage disorders that are associated with mutations in at least eight genes. Mutations in the TPP1 (CLN2) gene are most commonly associated with the classic late-infantile neuronal ceroid-lipofuscinosis (LINCL) form that is characterized by onset of symptoms between 2 and 4 years. Epilepsy is typically […]

The neuronal ceroid-lipofuscinoses are a group of inherited, neurodegenerative, lysosomal storage disorders that are associated with mutations in at least eight genes. Mutations in the TPP1 (CLN2) gene are most commonly associated with the classic late-infantile neuronal ceroid-lipofuscinosis (LINCL) form that is characterized by onset of symptoms between 2 and 4 years. Epilepsy is typically the presenting symptom followed by regression of developmental milestones; speech delay, slow learning, intellectual disability, dementia, and neuromotor dysfunction including ataxia and the inability to walk are characteristic. Visual impairment typically appears at age 4 to 6 years, with rapid progression to blindness. Life expectancy ranges from 6 years to older than 40 years. Some patients with mutations in the TPP1 gene have been reported with juvenile neuronal ceroid-lipofuscinosis (JNCL) presentation that is characterized by later onset with the presenting symptom being visual impairment, followed by epilepsy. As a group the neuronal ceroid-lipofuscinoses are the most common hereditary progressive neurodegenerative disease with an incidence ranging from 1 to 7 per 100,000 births.

Tests Available

TPP1 (CLN2) Gene Sequencing

FORMS AND DOCUMENTS

TEST DETAILS

Genes:
TPP1 (CLN2)
Clinical Utility:
  • Confirmation of biochemical diagnosis
  • Carrier testing
  • Prenatal diagnosis in at risk pregnancies
Lab Method:
Capillary Sequencing

ORDERING

Test Code:
607
Turnaround Time:
4-5 weeks
Preferred Specimen:
2-5 mL Blood - Lavender Top Tube
Alternative Specimen:
Oral Rinse (30-40 mL)

BILLING

CPT Codes:
81479x1
New York Approved:
No
ABN Required:
Yes
Billing Information:
View Neurology Billing Policy
* For ICD9 to ICD10 conversion please follow this link https://www.aapc.com/icd-10/codes/
ICD-9 Codes:
  • 345: Epilepsy and recurrent seizures The following fifth-digit subclassification is for use with categories 345.0, .1, .4-.9: 0 without mention of intractable epilepsy 1 with intractable epilepsy pharmacoresistant (pharmacologically resistant) poorly controlled treatment resistant refractory (medically) Excludes: hippocampal sclerosis (348.81) mesial temporal sclerosis (348.81) progressive myoclonic epilepsy (333.2) temporal sclerosis (348.81)
  • 272.7: Lipidoses (Fabry Disease)
  • 369: Blindness and low vision Excludes: correctable impaired vision due to refractive errors (367.0-367.9) Note: Visual impairment refers to a functional limitation of the eye (e.g., limited visual acuity or visual field). It should be distinguished from visual disability, indicating a limitation of the abilities of the individual (e.g., limited reading skills, vocational skills), and from visual handicap, indicating a limitation of personal and socioeconomic independence (e.g., limited mobility, limited employability). The levels of impairment defined in the table after 369.9 are based on the recommendations of the WHO Study Group on Prevention of Blindness (Geneva, November 6-10, 1972; WHO Technical Report Series 518), and of the International Council of Ophthalmology (1976). Note that definitions of blindness vary in different settings. For international reporting, WHO defines blindness as profound impairment. This definition can be applied to blindness of one eye (369.1, 369.6) and to blindness of the individual (369.0). For determination of benefits in the U.S.A., the definition of legal blindness as severe impairment is often used. This definition applies to blindness of the individual only.
* For price inquiries please email zebras@genedx.com

REFERENCES

  1. Mole, S. and Williams, R. (Updated [March 2, 2010])Neuronal Ceroid-Lipofuscinoses. In: GeneReviews at Genetests: Medical Genetics Information Resource (database online). Copyright, University of Washington, Seattle. 1997-2011. Available at http://www.genetests.org.
  2. Hofmann et al., (2002) Curr Mol Med 2:423-437.
  3. Sleat et al., (1999) Am J Hum Genet 64:1511-1523.
  4. Zhong et al., (2000) Genet Med 2:312-318.

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