A modest increase in CD4+ T-cell count at PML-IRIS onset was previously reported14and was comparable to the CD4+ T-cell counts observed in PML patients before the cART era.19Another study showed that the rise in CD4+ T-cell counts from baseline to IRIS diagnosis was not statistically significant.27In contrast, the rise of CD4 cell count over the first 3 months of cART was associated with IRIS.28This finding suggests that longer time periods of observation may be needed to detect immunological changes associated with IRIS. The gene discussed is CD4; the disease is progressive multifocal leukoencephalopathy.