Intriguingly, the expression of the putative ALS biomarkers CHIT1, CHI3L1, and MCP-1 was strongly enriched in most microglial cells compared with blood monocytes, suggesting that microglia are likely to be a key source of these biomarkers and a suitable model to study their release in vitro. The gene discussed is CHIT1; the disease is amyotrophic lateral sclerosis.