Angiotensinogen promoter haplotypes are associated with blood pressure in untreated hypertensives

The polymorphic angiotensinogen (AGT) gene is one of the most promising candidates for blood pressure (BP) regulation and essential hypertension.

To investigate whether AGT haplotype analysis adds significant information compared to single polymorphism analysis with respect to different BP phenotypes in an untreated hypertensive sample.

Two hundred and twelve untreated hypertensive subjects of Caucasian origin were genotyped for the AGT polymorphisms C-532T, A-20C, C-18T, and G-6A.

In single variant analyses, untreated hypertensives, carrying the AGT -532T or -6A alleles had significantly higher systolic blood pressure (SBP) and diastolic blood pressure (DBP), as well as ambulatory BP values compared to respective non-carriers. In haplotype-based analyses, combining all four AGT promoter variants, we demonstrate that AGT haplotypes containing different allele combinations at positions -532 and -6 were significantly associated with different BP values: (1) -532T and -6A with higher, (2) -532C and -6G with lower, (3) -532C and -6A with intermediate BP values. Since the result for the -532C/-20A/-18C/-6G haplotype was due to differences between non-carriers and carriers of this haplotype on both chromosomes, a recessive inheritance model for BP effects could be assumed.

Our results designate the C-532T and G-6A as the best candidates for functional studies on the AGT gene. Haplotype-based analyses should greatly aid in the dissection of the genetic basis of complex traits, such as BP regulation and hypertension.