For manifest HD participants, NfL but not GFAP was significantly increased in stage 1 compared with premanifest ones (preHD vs. stage 1, NfL: 2.69 ± 0.99 vs. 4.69 ± 0.68 log pg/ml, p < 0.0001; GFAP: 5.77 ± 0.74 vs. 5.88 ± 0.65 log pg/ml, p > 0.05). This evidence concerns the gene NEFL and Huntington disease.