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Test ID: C9ORF C9orf72 Hexanucleotide Repeat, Molecular Analysis

Useful For

Molecular confirmation of clinically suspected cases of c9FTD/ALS, frontotemporal dementia (FTD), or amyotrophic lateral sclerosis (ALS)


Presymptomatic testing for individuals with a family history of c9FTD/ALS and a documented expansion in the C9orf72 gene

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
C9FU C9orf72, Follow Up Analysis No No

Method Name

Polymerase Chain Reaction (PCR)

Reporting Name

C9orf72, Molecular Analysis

Specimen Type


Shipping Instructions

Specimen preferred to arrive within 96 hours of collection.

Specimen Required

Specimen Type: Whole blood


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)

Clinical Information

Frontotemporal dementia (FTD) is a presenile dementia that affects the frontal and temporal lobes of the brain. Clinical presentation is variable and includes progressive changes in behavior and personality and language disturbances. Affected individuals may also exhibit extrapyramidal signs.


Amyotrophic lateral sclerosis (ALS) is a progressive neurologic disease affecting the upper and lower motor neurons. The disease is characterized by progressive spasticity, muscle wasting and paralysis, typically leading to death from respiratory failure.


ALS and FTD are now thought to represent an overlapping spectrum of disease. Recent literature has found that approximately 40% of familial ALS and FTD cases have a large hexanucleotide repeat (GGGGCC) expansion in a noncoding region of C9orf72.

Reference Values

Normal alleles: <20 GGGGCC repeats

Intermediate alleles: 20-29 GGGGCC repeats

Full penetrance: >29* GGGGCC repeats


*Alleles greater than 30 repeats are outside the reportable range for this assay and are detected using the companion Southern blot assay. There is not enough information at this time to determine if 30 repeats is the cutoff for pathogenicity.


An interpretive report will be provided.


An interpretive report will be provided.

Clinical Reference

1. DeJesus-Hernandez M, Mackenzie IR, Boeve BF, et al: Expanded GGGGCC hexanucleotide repeat in noncoding region of C9ORF72 causes chromosome 9p-linked FTD and ALS. Neuron 2011;72(2):245-256

2. Gijselinck I, Van Langenhove T, van der Zee J, et al: A C9orf72 promoter repeat expansion in a Flanders-Belgian cohort with disorders of the frontotemporal lobar degeneration-amyotrophic lateral sclerosis spectrum: a gene identification study. Lancet Neuro 2012;11(1):54-65

3. Boeve BF, Boylan KB, Graff-Radford NR, et al: Characterization of frontotemporal dementia and/or amyotrophic lateral sclerosis associated with the GGGGCC repeat expansion in C9ORF72. Brain 2012;135(Pt 3):765-783

Day(s) and Time(s) Performed

Tuesday; 10 a.m.

Analytic Time

5 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

81479-Unlisted Molecular Pathology procedure


Reflex Tests

C9orf72, Follow Up Analysis

81479-Unlisted Molecular Pathology procedure

LOINC Code Information

Test ID Test Order Name Order LOINC Value
C9ORF C9orf72, Molecular Analysis In Process


Result ID Test Result Name Result LOINC Value
52852 Result Summary 50397-9
52853 Result 77635-1
52854 Interpretation 69047-9
52855 Reason for Referral 42349-1
52856 Specimen 31208-2
55158 Method 49549-9
52857 Source 31208-2
52858 Released By No LOINC Needed


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 (

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information: