title: Genetic African Ancestry and Markers of Mineral Metabolism in CKD.
abstract: OBJECTIVE
  Disorders of mineral metabolism are more common in African Americans with CKD than in European Americans with CKD. Previous studies have focused on the differences in mineral metabolism by self-reported race, making it difficult to delineate the importance of environmental compared with biologic factors.
  
  
  METHODS
  In a cross-sectional analysis of 3013 participants of the Chronic Renal Insufficiency Cohort study with complete data, we compared markers of mineral metabolism (phosphorus, calcium, alkaline phosphatase, parathyroid hormone, fibroblast growth factor 23, and urine calcium and phosphorus excretion) in European Americans versus African Americans and separately, across quartiles of genetic African ancestry in African Americans (n=1490).
  
  
  RESULTS
  Compared with European Americans, African Americans had higher blood concentrations of phosphorus, alkaline phosphatase, fibroblast growth factor 23, and parathyroid hormone, lower 24-hour urinary excretion of calcium and phosphorus, and lower urinary fractional excretion of calcium and phosphorus at baseline (P<0.001 for all). Among African Americans, a higher percentage of African ancestry was associated with lower 24-hour urinary excretion of phosphorus (Ptrend<0.01) in unadjusted analyses. In linear regression models adjusted for socio-demographic characteristics, kidney function, serum phosphorus, and dietary phosphorus intake, higher percentage of African ancestry was significantly associated with lower 24-hour urinary phosphorus excretion (each 10% higher African ancestry was associated with 39.6 mg lower 24-hour urinary phosphorus, P<0.001) and fractional excretion of phosphorus (each 10% higher African ancestry was associated with an absolute 1.1% lower fractional excretion of phosphorus, P=0.01).
  
  
  CONCLUSIONS
  A higher percentage of African ancestry was independently associated with lower 24-hour urinary phosphorus excretion and lower fractional excretion of phosphorus among African Americans with CKD. These findings suggest that genetic variability might contribute to racial differences in urinary phosphorus excretion in CKD.
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material. ogutierr@uab.edu.
authors.forename: Orlando M
authors.initials: OM
authors.lastname: Gutiérrez
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Afshin
authors.initials: A
authors.lastname: Parsa
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Tamara
authors.initials: T
authors.lastname: Isakova
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Julia J
authors.initials: JJ
authors.lastname: Scialla
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: John M
authors.initials: JM
authors.lastname: Flack
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Nessel
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Jayanta
authors.initials: J
authors.lastname: Gupta
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Bellovich
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Susan
authors.initials: S
authors.lastname: Steigerwalt
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: James H
authors.initials: JH
authors.lastname: Sondheimer
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Jackson T
authors.initials: JT
authors.lastname: Wright
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Harold I
authors.initials: HI
authors.lastname: Feldman
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: John W
authors.initials: JW
authors.lastname: Kusek
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: James P
authors.initials: JP
authors.lastname: Lash
authors.affiliation: Due to the number of contributing authors, the affiliations are provided in the Supplemental Material.
authors.forename: Myles
authors.initials: M
authors.lastname: Wolf
mesh_terms: D000328:Adult; D001741:Black or African American / Q000235:genetics*; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D044383:Black People; D002118:Calcium / Q000378:metabolism; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010758:Phosphorus / Q000378:metabolism*; D051436:Renal Insufficiency, Chronic / Q000208:ethnology / Q000235:genetics* / Q000378:metabolism*; D044465:White People; D055815:Young Adult
chemical_list: D015415:Biomarkers; D010758:Phosphorus; D002118:Calcium
keywords: African Americans; Cohort Studies; Fibroblast Growth Factors; Humans; Phosphorus; Renal Insufficiency, Chronic; chronic kidney disease; mineral metabolism; parathyroid hormone