QPRT and chronic kidney disease: According to this computational model, QPRT was progressively reduced along the transition to CKD (Figure 2F), a finding confirmed by immunohistochemistry in kidney biopsies obtained from patients with CKD (Figure 2G), by the correlation between renal function and QPRT transcript levels in urinary cell pellets in a cohort of 55 CKD patients (Figure 2H and Supplemental Table 7 for clinical data), and by a lower expression of QPRT transcripts in human diabetic renal tubular tissues (14) (Figure 2I).