Further analysis of to determine the impact of host 25- hydroxyvitamin D levels on immune recovery revealed that in patients who received vitamin D supplementation, MTBs-induced IFN-g secretion was significantly increased after 12 week of anti-tuberculous therapy only in patients who had ‘Deficient’ 25-hydroxyvitamin D levels (< 20 ng/mL) at initiation of treatment whilst this immune recovery was absent for TB patients with ‘Deficient’ 25- hydroxyvitamin D levels in the placebo group. The gene discussed is IFNG; the disease is tuberculosis.