Regarding other diseases, a prior study(17) reported that A allele at 2109 locus of IFN-γ gene was less frequent in patients with hepatic schistosomiasis-associated periportal fibrosis than control group, while other studies showed no association between this polymorphism and microscopic-positive tuberculosis (21), and also another study reported that pulmonary tuberculosis was not associated with IFN-γ gene polymorphisms at +2109 locus. The gene discussed is IFNG; the disease is Periportal fibrosis.