Polymorphisms within Fas gene are not associated with occult hepatitis B virus infection

Background: occult hepatitis b infection (obi) is a form of hepatitis in which there is an absence of detectable hbsag, despite the presence of hbv-dna in the peripheral blood of patients. it seems that non-effective or attenuated immune system responses against hbv lead to the development of obi. previous studies showed that the fas/fas ligand (fasl) system is an important death signaling pathway that is used by cytotoxic t lymphocytes to eradicate hbv from the liver.objectives: to investigate polymorphisms in the -670 region of the fas gene in those with obi.patients and methods: the plasma samples from 3700 blood donors were tested for hbsag and anti-hbs by elisa. the hbsag-/anti-hbc+ samples were selected and screened for hbv-dna by pcr. those with hbv-dna were diagnosed as obi and pcr-rflp technique was performed to examine polymorphisms within their fas gene.results: 352 (9.5%) of 3700 blood samples were hbsag-/anti-hbc+. hbv-dna was detected in 57 (16.1%) of 352 hbsag-/anti-hbc+ samples. therefore, 57 hbsag-/anti-hbc+/hbv-dna+ patients were diagnosed as obi. patient and control groups had no significant differences in terms of the studied polymorphisms.conclusions: the functional polymorphisms in the promoter region of fas gene are not associated with obi. therefore, it may be concluded that polymorphisms at the -670 position of the fas gene do not have any critical effects on the immune response against hbv in obi.