GFAP and Alexander disease: Overall, the contribution of astrocytes to the pathology of leukodystrophies is of expanding interest [38], sparked by findings that mutations specifically in astrocyte-expressing glial-fibrillary acidic protein (GFAP) gene cause demyelinating Alexander disease [39], defective support and differentiation of astrocytes results in vanishing white matter disease [40–42], and astrocyte dysfunction precedes demyelination observed in X-linked adrenoleukodystrophy [43], among many others [44, 45].