FTO and obesity due to melanocortin 4 receptor deficiency: The FTO story constitutes a textbook case: the FTO gene has been cloned in mice in 1999 [31] but the “buzz” around this gene started after the publication of two seminal genetic studies demonstrating a link between FTO common gene variation and human obesity in 2007 (at this time, FTO was a gene of unknown function in an unknown pathway) [18, 19].