NEFL and tropical spastic paraparesis: Several other non-cytokine biomarkers, such as CXCL10 (also known as IP-10), Neurofilament Light Chain (NFL), and Chitotriosidase-1 (encoded by the CHIT1 gene) have recently been proposed as biomarkers for HAM/TSP disease progression [4, 5, 8, 33, 53–58].