Genetic basis of essential hypertension in Tibetan

To explore the role genetic factor plays in the pathogenes is of essential hypertension (EH) among Tibetans and to investigate whether angiotensinogen (AGT) is involved in the pathogenesis of EH. A case-control association study was conducted among 353 essential hypertensive subjects and 317 genealogic structure-matched normotensive controls, all of Tibetan nationality. The correlation between polymorphism of M235T and 6A-->G variant in AGT gene and EH susceptibility in Tibetans was examined by polymerase chain reaction ( PCR) and PCR/RFLP (restriction fragment lengths polymorphism) with AspI and BstN I,respectively. (1) The affection rate of EH among the first-degree relatives of Tibetan EH proband was 43.3%. The heritability of EH was 77.2% +/- 13.3% by Falconer method. (2) The plasma rennin activity and angiotensin II (AngII) level among the EH patients were (1.95 +/- 0.11) microgram .L(-1).h(-1) and (72.6 +/- 4.6) ng/L, all significantly higher than those in the controls [(1. 59 +/- 0.11) microgram .L(-1).h(-1) and (51.7 +/- 4.6) ng/L, all P < 0.05].(3) The -6G allele frequency in the promoter of AGT gene was higher in EH group than in the control group (0.36 vs 0.27, kappa(2) = 9.35, P < 0.01). There was a weak association between -6A -->G variant and the plasma AngII level, and there was no significant difference in the genotype distribution and allele frequency of M235T variant between the hypertensive and normotensive groups (P > 0.05). Genetic factor plays an important role in the pathogenesis of essential hypertension and angiotensinogen gene might be one of the most key susceptibility genes for essential hypertension in Tibetan.