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Motor neurone disease (MND) is the umbrella term for a group of degenerative diseases of the motor neurons, of which amyotrophic lateral sclerosis is the most common form. The incidence of MND is around 2 per 100,000 globally and median survival time is approximately 3 years from symptom onset.1
MND may be either familial or sporadic, with the vast majority of cases (95%) being sporadic.2 Genetic characterisation of international cohorts shows this to be a somewhat artificial distinction-at least 1 in 10 sporadic cases carry a heritable genetic mutation.3 However New Zealand MND patients are yet to be represented in those cohorts. Indeed, there is a woeful lack of publicly available data on the demographics, aetiology (including genetics) and provision of care of MND patients in New Zealand thus far.
Outside of New Zealand, there have been significant recent advances in the genetic characterisation of both sporadic and familial MND. This has been made possible by massively parallel DNA sequencing technology which can process more samples for a fraction of the time and cost of previous methods.
To date, 33 disease-causing genes have been identified,4 accounting for around 15% of all ALS cases.3 Notably, the same genetic mutations are present in both sporadic and inherited forms of MND, dispelling previous notions that these were distinct diseases. Furthermore, many of these genes can also cause frontotemporal dementia, consolidating the clinical and neuropathological picture of MND and frontotemporal dementia as a spectrum of overlapping diseases.
Disease-causing genes implicate dysfunction of gene expression (RNA processing), protein degradation, and cargo trafficking in the degeneration of motor neurons which causes MND. It is likely that the genetic profile of MND in New Zealand will largely resemble that of the UK and Europe, given the ancestry of New Zealand Europeans, however the genetics of Mäori and Pacifica MND is currently a black box.
Although a rare disease, MND is certainly under-studied...