A new study shows an independent association between genetic African ancestry and level of urinary phosphorous excretion in African Americans with chronic kidney disease (CKD). In their analysis of 3,013 patients, Gutiérrez et al. found that each 10% higher percentage of African ancestry was significantly associated with a 39.6 mg lower level of 24 h urinary phosphorous excretion and a 1.1% lower fractional excretion of phosphorous. They conclude that genetic factors contribute to racial differences in urinary phosphorous excretion among patients with CKD.