Obesity results in increased hepatotoxicity and decreased survival after exposure to LPS in both of the obese strains of Zucker fatty/fatty rats and obese/obese mice, suggesting two mechanisms that might mediate obesity-related sensitivity to endotoxin: altered Kupffer cell function; and increased hepatocyte sensitivity to TNF-α [13]. The gene discussed is TNF; the disease is obesity due to melanocortin 4 receptor deficiency.