GFAP and depressive symptom measurement: The epigenetic differences between subjects with depression and controls also extend to the pattern of DNA methylation for genes expressed at a high level in astrocytes as compared to other cell types (Nagy et al., 2015) including GFAP, ALDHL1, SLC1A3, GJA1, GJB6, GLUL and SOX9, all of which are found to be reduced in the dorsolateral prefrontal cortex of subjects with depression (Nagy et al., 2015).