Spontaneous expansion of the CAG repeat stretch in the CAG 140 KI mouse model, which carries a chimeric mouse / human exon 1 containing around 125 CAG repeats and the human polyproline region inserted in
the murine huntingtin gene (Menalled et al., 2003, Hickey et al., 2008), has recently led to a new KI line that carries around 190 CAG repeats (CAG 190 KI) in a congenic C57Bl / 6J background.
Numerous mouse models have been generated to examine the pathogenesis of the disease and to evaluate therapeutic approaches, but the most precise genetic reproductions of the human condition are the knock - in (KI) mouse models which express the
huntingtin mutation in the proper genetic and protein context on the
murine gene.