FTO and obesity due to melanocortin 4 receptor deficiency: For instance, nearly 8 years and the efforts of many researchers were necessary to unravel the molecular mechanism of the first GWAS-identified obesity gene, FTO (fat mass and obesity-associated protein), via integrative analyses of epigenomic data, allelic activity, motif conservation, gene regulator expression and gene co-expression patterns, and target genome editing verification [7].