Motor Neurone Disease: C9orf72 repeat expansion

Diagnostic Use

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease involving both the brain and spinal cord. While it has traditionally been perceived to be a syndrome primarily affecting motor neurons, there is increasing recognition that additional areas within the frontal and temporal lobes are involved to varying degrees in a subset of individuals. In addition, other systems outside the nervous system may be involved, such as bone (Paget disease of the bone) and muscle (inclusion body myopathy). The location and extent of the degeneration determines the clinical picture, which by definition includes motor decline, and may include cognitive and/or behavioral symptoms as well. There is wide variability in presentation, progression, and survival (PMID 28980624).

About half of familial ALS cases have a pathogenic variant in one of 30 genes associated with the disease. Of these, the four most commonly-implicated genes are C9orf72, SOD1, FUS and TARDBP (TDP-43) (PMID 20301623).

C9orf72 repeat expansions are the most common cause of ALS, and are implicated in 39-45% of familial ALS, and 3-7% of sporadic ALS. This form of ALS is also associated with behavioural variant frontotemporal dementia (FTD).

Sequencing of SOD1 is also available at this laboratory, while sequencing of the FUS and TARDBP genes is available on specific request. However, onward referral for a larger gene panel may be more clinically-appropriate and cost-effective. Please contact our laboratory to discuss additional testing, if required.


Genetics - Molecular Pathology

Delphic Registration Code


Constituent Tests


Amyotrophic Lateral Sclerosis
Frontotemporal dementia

Turnaround Time

4 weeks