This confounding body weight phenotype is also observed in the YAC128 mouse, another full-length mutant htt model that displays motor deficits and selective neurodegenerative pathology 9,10,11,12,13,14,15,16, and it was demonstrated that full-length mutant htt modulates body weight in both BAC HD and YAC128 models by influencing insulin-like growth factor-1 expression 1,9. Here, HTT is linked to Huntington disease.