PROS1 and amyotrophic lateral sclerosis: The finding of decreases in module 2 synaptic proteins in ALS is consistent with previous work in ALS, but differs from Alzheimer’s disease, in which increases in levels of synaptic proteins in CSF have been observed (Dayon et al., 2018; Portelius et al., 2018; Higginbotham et al., 2020).