Enhancer reporter constructs, including the modified BAC, were created as previously reported42. The human (NCBI37/hg19) genomic coordinates of the elements cloned are: FTO-1: chr16:53800270–53805184; FTO-2: chr16:53808432–53813121; FTO-3: chr16:53816312–53821148. FTO-promoter: chr16:53736860–53738096; IRX3-promoter: chr16:54319963–54322782. BAC RP11-261B9 was modified by inserting a lacZ-Amp cassette in place of the 36 nucleotides in exon 1 at chr16:53,738,097–53,738,132. This homologous recombination was facilitated by using the following homology arms: FTO-hArm1: chr16:53738047–53738096; FTO-hArm2: chr16:53738133–53738182.
