title: A polymorphism in the major gene regulating serum uric acid associates with clinic SBP and the white-coat effect in a family-based study.
abstract: OBJECTIVE
  Hyperuricemia associates with hypertension, but it is uncertain whether this relationship is causal in nature. Glucose transporter 9 (GLUT9) gene is a major genetic determinant of plasma uric acid levels in humans. Since polymorphisms are randomly distributed at mating (Mendelian randomization), studies based on GLUT9 polymorphisms may provide unconfounded assessment of the nature of the link between uric acid and hypertension.
  
  
  METHODS
  We tested the association between uric acid, the rs734553 polymorphism of the GLUT9 gene and arterial pressure in a family-based study including 449 individuals in a genetically homogenous population in Southern Italy.
  
  
  RESULTS
  Serum uric acid levels were strongly associated (P < 0.001) with all components of clinic and 24-h ambulatory blood pressures (BPs). However, only clinic SBP and the white-coat effect (the difference in clinic systolic and daytime systolic ambulatory blood pressure monitoring) associations remained significant after adjustment for classical risk factor and the estimated glomerular filtration rate. Serum uric acid was strongly associated with the risk allele (T) of the rs734553 polymorphism (P < 0.001). Furthermore, TT individuals showed higher clinic SBP (129 + SEM 1 mmHg) than GT (125 + 1 mmHg) and GG individuals (122 + 3 mmHg), as well as a higher white-coat effect (P = 0.02), confirming that the association between uric acid and these BP components is unconfounded by environmental risk factors.
  
  
  CONCLUSIONS
  Results in this family-based study are compatible with the hypothesis that uric acid is a causal risk factor for hypertension. Trials testing uric acid-lowering interventions are needed to definitively establish the causal implication of hyperuricemia in human hypertension. [Corrected]
authors.affiliation: aCNR-IBIM, Reggio Calabria bUnità Operativa di Nefrologia, Ipertensione e Trapianto Renale Ospedali Riuniti, Reggio Calabria, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Mallamaci
authors.forename: Alessandra
authors.initials: A
authors.lastname: Testa
authors.forename: Daniela
authors.initials: D
authors.lastname: Leonardis
authors.forename: Rocco
authors.initials: R
authors.lastname: Tripepi
authors.forename: Anna
authors.initials: A
authors.lastname: Pisano
authors.forename: Belinda
authors.initials: B
authors.lastname: Spoto
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Sanguedolce
authors.forename: Rosa Maria
authors.initials: RM
authors.lastname: Parlongo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tripepi
authors.forename: Carmine
authors.initials: C
authors.lastname: Zoccali
mesh_terms: D000818:Animals; D018660:Blood Pressure Monitoring, Ambulatory; D005838:Genotype; D051246:Glucose Transport Proteins, Facilitative / Q000235:genetics*; D006801:Humans; D033461:Hyperuricemia / Q000150:complications; D020641:Polymorphism, Single Nucleotide; D013599:Systole / Q000502:physiology*; D014527:Uric Acid / Q000097:blood*; D059466:White Coat Hypertension / Q000209:etiology*
chemical_list: D051246:Glucose Transport Proteins, Facilitative; C411811:SLC2A9 protein, human; D014527:Uric Acid