Having observed a higher production of IL-6, authors treated cultured rat primary cortical neurons with PBMC supernatants for 6 h (1:100 ratio of supernatant to medium) and demonstrated that PBMC supernatant from the ALS-twin, but not that of the healthy twin, was toxic for neurons and increased their degeneration. The gene discussed is IL6; the disease is amyotrophic lateral sclerosis.