In HAM/TSP patients, CSF levels of CHIT1 positively correlated with neopterin, a byproduct from the monocyte/macrophage inflammatory response (Spearman R = 0.603, p = 0.005), and with the phosphorylated neurofilament heavy protein (pNfH), a biomarker for neuronal damage (Spearman R = 0.627, p = 0.003). The gene discussed is CHIT1; the disease is tropical spastic paraparesis.