Specifically, an increased density of astrocytes and an upregulation of the astrocytic glial fibrillary acidic protein (GFAP), considered a canonical marker of astrocyte reactivity (Buffo et al., 2008; Kamphuis et al., 2012; Hol and Pekny, 2015; Escartin et al., 2021), is seen in postmortem brains of patients with HD (Selkoe et al., 1982; Vonsattel et al., 1985). The gene discussed is GFAP; the disease is Huntington disease.