The beginning of precision medicine in ALS?

Amyotrophic lateral sclerosis (ALS) affects approximately 1 in 400 adults of western European ancestry, making it the most common degenerative disease of the motor neuron network. ALS has a mean age at onset of 65 and 85%–90% of cases occur sporadically. Ten to fifteen percent of cases have a recognized genetic contribution, usually in known ALS gene-carrying families.1 In populations of European extraction, the commonest cause of familial ALS, accounting for up to 40% of familial cases, is the C9orf72 hexanucleotide repeat expansion.2 C9orf72 has a broader associated phenotype including frontotemporal dementia and a more rapid clinical progression. Men with spinal-onset disease have a lower median age at onset and drive the more rapid clinical progression.2 Other gene variants also associate with earlier age at onset and more rapid progression; for example, the A4V variant mutated SOD1 gene.3