For the further classification of an ALS frontal cortex samples to a specific subtype (C9orf72-ALS or sporadic ALS), the genes identified as the topmost determinative for the LASSO-genes-trained classifiers had also been identified as important, but not among the topmost determinative, for the SES- genes-trained classifiers. Here, C9orf72 is linked to amyotrophic lateral sclerosis.