The average General OX40 Immunity Index (G-OII) value for the PML patients of 6.3 ± 3.0 was lower than for MS patients without PML, 24.9 ± 5.2 (Figure 2C), especially PML #2 (reactivation) with an extremely weak G-OII value of 0.7. Here, TNFRSF4 is linked to progressive multifocal leukoencephalopathy.