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Test ID: MAPTZ MAPT Gene, Sequence Analysis, 7 Exon Screening Panel

Useful For

Aiding in the diagnosis of frontotemporal dementia, progressive supranuclear palsy, corticobasal degeneration, and dementia with epilepsy

 

Distinguishing the diagnosis of frontotemporal dementia from other dementias, including Alzheimer dementia

 

Identifying individuals who are at risk of frontotemporal dementia

Method Name

Polymerase Chain Reaction (PCR)/DNA Sequencing Analysis

Reporting Name

MAPT Gene, Sequencing Analysis

Specimen Type

Varies


Shipping Instructions


Specimen preferred to arrive within 96 hours of draw.



Specimen Required


Specimen Type: Whole blood

Container/Tube:

Preferred: Lavender top (EDTA) or yellow top (ACD)

Acceptable: Any anticoagulant

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Varies Ambient (preferred)
  Frozen 
  Refrigerated 

Clinical Information

Frontotemporal dementia is a familial adult-onset, presenile dementia that affects the frontal and temporal cerebral cortices. Clinical presentation is variable and includes changes in behavior, difficulties with language, rigidity, palsy, and saccadic (rapid) eye movement. Symptoms generally begin between 40 and 60 years of age, with mean age of onset at approximately 45 years, and typically last between 5 and 10 years, progressing to severe dementia and mutism. The presentation of frontotemporal dementia may be confused with other dementias, including Alzheimer disease. It is important to distinguish between these different dementias because progression and patient management are different for the various dementias.

 

Based on the immunohistochemical staining, there are 2 main subtypes of frontotemporal lobular degeneration (FTLD): tau-positive FTLD and tau-negative FTLD with ubiquitin-positive inclusions (FTLD-U). Mutations in the MAPT gene have been identified in patients with tau-positive FTLD; mutations in the progranulin gene (GRN) have been identified in patients with FTLD-U. Both MAPT and GRN are located on chromosome 17q21.

 

The MAPT gene encodes the microtubule-associated tau protein. A number of mutations have been identified in the MAPT gene that result in aggregation of the tau protein. Although there is variable expression of disease presentation and severity within and between families, the hallmark neurologic lesion constitutes tau-positive protein inclusion bodies. Most clinically significant mutations are found in exons 9 through 13. Several intronic mutations, associated with alternative splicing of the mRNA, contribute to the variability of expression of the disease traits. Mutations in the MAPT gene have also been identified in cases of progressive supranuclear palsy, corticobasal degeneration, and dementia with epilepsy.

Reference Values

An interpretive report will be provided.

Interpretation

All detected alterations are evaluated according to American College of Medical Genetics recommendations.(1) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.

 

All variants will be reported in reference to transcript NM_001123066 (build GRCh37 (hg19)).

Clinical Reference

1. Richards S, Aziz N, Bale S, et al: Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med 2015 May;17(5):405-424

2. Rademakers R, Cruts M, van Broeckhoven C: The role of tau (MAPT) in frontotemporal dementia and related tau pathies. Hum Mutat 2004 Oct;24(4):277-295

3. Houlden H, Baker M, Adamson J, et al: Frequency of tau mutations in three series of non-Alzheimer's degenerative dementia. Ann Neurol 1999 Aug;46(2):243-248

4. Goedert M: Tau protein and neurodegeneration. Semin Cell Dev Biol 2004 Feb;15(1):45-49

5. Dumanchin C, Camuzat A, Campion D, et al: Segregation of a missense mutation in the microtubule-associated protein tau gene with a familial frontotemporal dementia and parkinsonism. Hum Mol Genet 1998 Oct;7(11):1825-1829

Day(s) and Time(s) Performed

Performed weekly; Varies

Analytic Time

14 days

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

81406-MAPT (microtubule-associated protein tau) (eg, frontotemporal dementia), full gene sequence

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MAPTZ MAPT Gene, Sequencing Analysis In Process

 

Result ID Test Result Name Result LOINC Value
53964 Result Summary 50397-9
53965 Result In Process
53966 Interpretation In Process
53967 Additional Information 48767-8
53968 Specimen In Process
53969 Source 31208-2
53970 Released By No LOINC Needed

Forms

1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.

2. Molecular Genetics: Neurology Patient Information in Special Instructions

3. If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/neurology-request-form.pdf

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

mml-inherited-molecular