VDR and chronic kidney disease: Also, a study on single-nucleotide polymorphisms of the vitamin D system, which include vitamin D receptor, vitamin D binding protein, and retinoic X receptor alpha, in chronic kidney disease patients associated only the rs1544410 polymorphism in the vitamin D receptor with non-response to the hepatitis B vaccine, which is more common with homozygotes “AA” and less common with homozygotes “GG” [28].