FTO and obesity due to melanocortin 4 receptor deficiency: However, the influence ofFTO variants has been controversial among different populations(Ohashi et al., 2007;Scuteri et al., 2007;Li et al., 2008; Ramos et al., 2012; Pereira et al., 2016).Moreover, there are only few studies associating FTO variants andextreme obesity, since sample selection is difficult and requires considerableeffort.