The observed molecular phenotypes may also be due to a loss of astrocyte identity rather than a developmental alteration, as suggested in a previous study67; however, the human HD iAstros data suggest a developmental phenotype given the decreased propensity for HD iPSCs to differentiate into GLAST-positive, morphologically mature astrocytes, similar to altered in vivo astroglial differentiation of human glial progenitor cells from HD embryonic stem cells.7 The gene discussed is SLC1A3; the disease is Huntington disease.