Several factors have been associated with responses to PEG-IFN/RBV therapy; some are associated with the host, such as interleukin 28B single nucleotide polymorphisms (IL28B SNPs), gender, race, age, and obesity [3–7], while some are virus-associated, such as viral genotype, viral load, amino acid (aa) substitution in the core and non-structural (NS) 5A region [8–10]. This evidence concerns the gene IFNL3 and obesity due to melanocortin 4 receptor deficiency.