PAX6 and Huntington disease: The staining results showed that the ratios of TBR2+PAX6-/TBR2-PAX6+ in the HD group were higher than those in the CTR group (Fig. 1L), indicating that early lineage specification of the neural progenitors was preceded in HD-hCOs, which is consistent with the observations in HD fetuses and embryos of HD mice [6].