To date, serum and CSF NEFL levels have only been reported in R6/2 mice with CAG expansions of 273–285, in which they were shown to increase with disease progression.32 To generate more comprehensive data sets, we performed longitudinal measures of the plasma and CSF levels of NEFL, total-Tau and breast regression protein 39 (BRP-39) (mouse YKL-40) in mouse models of Huntington’s disease. The gene discussed is CHI3L1; the disease is juvenile Huntington disease.