UDPGTs have been associated with a variety of bilirubin metabolic disorders and their mouse orthologs Ugt1a1, Ugt1a2, Ugt1a5, Ugt1a6b, Ugt1a7c, Ugt1a8, Ugt1a9, Ugt1a10 are mainly expressed in the liver at days 15.5 and 18.5 (Carnegie stages); corresponding to the 6th and 7th week of development in humans (WD, weeks from fertilization) [9,11,12]. Here, UGT1A8 is linked to metabolic disease.