Our plasma BRP-39 data showed less variation than NEFL and support the hypothesis that YKL-40 could be an important CSF biomarker for Huntington’s disease.31 The use of these fluid biomarkers in the validation of therapeutic targets and in preclinical drug screens could not only be important in the translation of therapies from mouse models to the clinic but may also shed light on the pathologies underlying these elevated biomarker levels. The gene discussed is CHI3L1; the disease is Huntington disease.