NMNAT1 and chronic kidney disease: In a study, impaired NAD+ synthesis in mice with CKD was associated with decreased expression of key enzymes, including quinolinate phosphoribosyl transferase (QPRT) in the NAD+ de novo synthesis pathway and nicotinamide nucleotide adenylyl transferase 1 (NMNAT1) and NMNAT 3 in the salvage synthesis pathway [54].