Considering that obesity, insulin resistance and steatosis have been identified as important factors that promote metabolic syndrome progression and failure of HCV therapy in HCV-infected patients [26], the aim of this study was to examine the association of the FTO rs9939609 polymorphism with the metabolic disturbances and virologic response to HCV therapy with pegIFNα/RBV in HIV/HCV-coinfected patients. The gene discussed is FTO; the disease is metabolic syndrome.