IDO1 and chronic kidney disease: The second associated region at 6p24.3 also showed significant associations with IDO activity and CKD (p = 9.70 × 10−4 and p = 5.89 × 10−4 for rs77624055, respectively) rs77624055 is a variant located in the intronic of the BMP6 (Bone Morphogenetic Protein 6) gene.