Association of CYP3A5 genotypes with blood pressure and renal function in African families

OBJECTIVERenal cytochrome P450 3A5 (CYP3A5) activity has been associated with blood pressure and salt sensitivity in humans. We determined whether CYP3A5 polymorphisms are associated with ambulatory blood pressure (ABP) and with glomerular filtration rate (GFR) in African families. METHODSUsing a cross-sectional design, 375 individuals from 72 families, each with at least two hypertensive siblings, were recruited through a hypertension register in the Seychelles (Indian Ocean). We analyzed the association between the CYP3A5 alleles (1, 3, 6 and 7) and ABP, GFR and renal sodium handling (fractional excretion of lithium), from pedigree data, allowing for other covariates and familial correlations. RESULTSCYP3A51 carriers increased their daytime systolic and diastolic ABP with age (0.55 and 0.23 mmHg/year) more than non-carriers (0.21 and 0.04 mmHg/year). CYP3A51 had a significant main effect on daytime systolic/diastolic ABP [regression coefficient (SE)−29.6 (10.0)/−8.2 (4.1) mmHg, P = 0.003/0.045, respectively] and this effect was modified by age (CYP3A51 × age interactions, P = 0.017/0.018). For night-time ABP, the effect of CYP3A51 was modified by urinary sodium excretion, not by age. For renal function, CYP3A51 carriers had a 7.6(3.8) ml/min lower GFR (P = 0.045) than non-carriers. Proximal sodium reabsorption decreased with age in non-carriers, but not in CYP3A51 carriers (P for interaction = 0.02). CONCLUSIONSThese data demonstrate that CYP3A5 polymorphisms are associated with ambulatory BP, CYP3A51 carriers showing a higher age- and sodium- related increase in ABP than non-carriers. The age effect may be due, in part, to the action of CYP3A5 on renal sodium handling.