C9orf72 Expansion Assay




Test Mnemonic

C9ORF

CPT Codes

  • 81479 - QTY (1)

Performing Laboratory

Prevention Genetics


Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
5 mLWhole bloodEDTA (Lavender) Ambient 

Alternate Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
5 mLWhole bloodACD A or B (Yellow) Ambient 
OtherExtracted DNAEDTA (Lavender) Ambient15 ug extracted DNA at a concentration of 20 ug/mL is required

Minimum Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
2 mL     

Stability

Environmental Condition Description
Ambient48 hours
Refrigerated1 week
FrozenUnacceptable

Days Performed

Upon receipt

Turnaround Time

15 days

Methodology

Name Description
Repeat-primed PCR and Fluorescent Fragment-Length Assay 

Reference Range

Clinical Info

The function of C9orf72 is unknown at this time. Nonetheless, nuclear RNA foci were detected in affected tissues of patients with expanded GGGGCC repeats, suggesting defective RNA processing (Rademakers et al. Nat Rev Neurol 8(8):423-434, 2012). The repeat-primed PCR test is used as a screening method for the presence or absence of a pathogenic GGGGCC hexanucleotide repeat expansion located in the first intron of C9orf72. Of note, this test is not designed to determine the number of GGGGCC repeats in alleles carrying the pathogenic expansion (Warner et al., 1996; Renton, 2011).