Reduction in the expression of NG2 and PDGFRA mRNA (stages V–VI/A–C, and stages III–IV/0–C and V–VI/A–C respectively), together with reduced numbers of NG2‐ and Olig2‐immunoreactive cells in the WM, points to progressive decline of the oligodendrocyte lineage in the frontal WM with disease progression, which is in line with the demonstration of early alterations of the oligodendrocyte lineage linked to AD pathology [105, 106]. The gene discussed is OLIG2; the disease is Alzheimer disease.