It is of note that all control animals but one had serum NfL concentration well below the lowest level of scrapie sheep (Table 1 and Fig 1) suggesting that this test is valuable for making an accurate screening of scrapie in living sheep The ROC curve (Table 1 and Fig 2) provided the cut-off value of 31 pg/ml serum NfL for distinguishing scrapie from control sheep with an accuracy of the test of 95% (percent error, 5.26%). This evidence concerns the gene NEFL and scrapie.