Sensitivity of HTT immunoassays compared to existing described in this paper.

Recombinant human HTT-Q73 (1–573) or mouse full-length HTT-Q7 was spiked into lysis buffer or mouse brain lysate (derived from wild type or homozygous zQ175DN mice for spiking human or mouse recombinant HTT, respectively). Serially dilutions of recombinant HTT in each of the matrices were measured with the indicated HTT MSD immunoassays (indicated as antibody pairs: capture/ detection), and LLoD concentration was back-calculated based on mean background signal + 3 x standard deviation. Dynamic range was estimated visually from the standard curves, which are shown in S4 Fig. *determined in 3 and 10 μg brain lysate instead of 20 and 40 μg, respectively.