HTT and Huntington disease: Having identified N-terminal htt fragments in individual subjects that could be attributed to longer PMDs, we next analyzed N-terminal htt fragments in post mortem tissue in nine human control subjects (mean age = 61.6 ± 15.5 years, mean PMD = 15.8 ± 5.3 hours) and nine human HD subjects (mean age = 61.0 ± 17.6 years, mean PMD = 14.3 ± 2.5 hours).