As such, a proteomic study of Portuguese patients with familial ALS (FALS), not carrying SOD1 mutations, isolated an isoform of DBP that was identified as GC2, which was absent in healthy controls, and noted a decrease of more acidic isoforms of DBP in FALS; collectively, these results suggest that GC2 polymorphism of DBP could constitute a risk factor for ALS [249]. Here, SOD1 is linked to amyotrophic lateral sclerosis.