Factors associated with anaemia at multivariable analysis were low BMI (odds ratio (OR) 2.93, 95% CI 1.70–5.05, P < 0.001), low CD4:CD8 ratio (OR 2.54, 95% CI 1.07–6.04, P = 0.035) and microcytosis (OR 4.23, 95% CI 2.17–8.25, P < 0.001). The gene discussed is CD8A; the disease is anemia.