Moreover, clinical risk factors already known to be associated with IRIS pathogenesis are (a) low baseline CD4+ T-cell count (< 50–100 cells per mm3) combined with a short time interval between the beginning of TB treatment and cART [38–42] and (b) dissemination of TB to extrapulmonary sites, possibly reflecting a high bacterial load [43, 44]. This evidence concerns the gene CD4 and tuberculosis.