The Chronic Kidney Disease Epidemiology cystatin C (CKD-Epi_cys) equation [16]: 133 × min(Scys/0.8, 1)‒ 0.499 × max(Scys/0.8, 1)‒ 1.328 × 0.996age(×0.932 if female); where Scys is serum cystatin C, min indicates the minimum of Scr/κ or 1, and max indicates the maximum of Scys/κ or 1. The gene discussed is CST3; the disease is chronic kidney disease.