When comparing the new BTP-based equations with the established creatinine/cystatin C-based CKD-EPI(Crea/CysC), BIS2 and FAS equations it was surprising that the Inker(BTP) equation showed a better performance of bias (−2 versus 7 ml/min/1.73 m2) and accuracy (P10 of 45% versus 40% and P30 of 91% versus 88%) than the CKD-EPI(Crea/CysC) equation. This evidence concerns the gene CST3 and chronic kidney disease.