Risk factors for Unmask-MC IRIS on multivariable analysis (Figure 4d) were current TB (aHR 2.00, CI 1.02–3.93, P = 0.045) and previous TB (aHR 2.30, CI 1.21–4.37, P = 0.011), vs. those with no history of TB, mild anaemia of Hb 10–12 vs. >12 g/dL (aHR 1.98, CI 1.04–3.78, P = 0.037), but not Hb <10 g/dL, and use of co-trimoxazole for at least one month prior to ART vs. starting co-trimoxazole concurrently with ART (aHR 1.97, CI 1.06–3.65, P = 0.032). The gene discussed is GSTM1; the disease is anemia.