GFAP and Alexander disease: A roughly 12% mosaic condition for GFAP c.236G>A (p.R79H) mutation, a genetic defect already shown in association with AxD and recurring in unrelated patients (Rodriguez et al., 2001; Asahina et al., 2006; Zang et al., 2013), has been demonstrated in blood cells of an AxD patient’s mother, and for this reason, it must have been present to an unknown extent in the lineage of the germ cells.