One such assay utilized in the field is the measurement of caspase activity.  Caspase activity is elevated in HD cell culture models, mouse models and postmortem tissue when compared to controls (11) .  Because caspase cleavage of huntingtin is an important step to generate toxic fragments, the activity of caspase reflects Htt-mediated cellular toxicity. The gene discussed is HTT; the disease is Huntington disease.