In the largest review of reported cases, HBV reactivation following anti-TNF therapy occurred in 39% (35/89) of HBsAg positive individuals, including 4 fatal cases of acute liver failure[20], and in 5% (9/168) of HBsAg-negative and anti-HBc-positive individuals, including 1 fatal case. The gene discussed is TNF; the disease is acute liver failure.