Amyotrophic lateral sclerosis (ALS) is a relentlessly progressive neurodegenerative disorder with no effective disease-modifying therapies at present. The disease is sporadic in 90 % of the ALS patients. Up to 40 % familial ALS cases and up to 25% of familial frontotemporal dementia (FTD) are caused by autosomal dominant GGGGCC hexanucleotide repeat expansions in the C9orf72 gene. The presymptomatic phase of the disease represents a unique opportunity to evaluate mechanisms of disease propagation, characterise patterns of anatomical spread, validate staging systems and appraise the comparative sensitivity profile of emerging imaging modalities. Very few spinal cord imaging studies currently exist in ALS despite their potential to characterise both the lower and upper motor neuron components of the disease. This prospective longitudinal study of asymptomatic and symptomatic c9orf72 hexanucleotide carriers will use a purpose-designed spinal and brain imaging protocol and comprehensive clinical, genetic, electrophysiological and neuropsychological profiling. Newly developed imaging techniques such as spinal cord NODDI, spinal fMRI, quantitative thoracic cord imaging will be implemented in addition to established spinal cord and brain imaging techniques.