Objective: To investigate the association of the transforming growth factor- beta 1 (TGF- beta 1) gene polymorphisms and blood TGF- beta 1 level with essential hypertension (EH) in Kazakh Chinese.
Methods: The polymorphisms of TGF- beta 1 gene in 354 Kazakh EH patients and 435 healthy controls were detected with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing. The blood level of TGF- beta 1 was quantified using specific sandwich ELISA.
Results: The frequencies of genotypes GG, GC and alleles G and C of +915G/C in Xinjiang Kazakh were 97.9%, 2.1% and 98.77%, 1.23%, respectively. No significantly difference was found between EH patients and controls (P>0.05). The frequencies of genotypes TT, TC, CC and alleles T and C of +869T/C in controls was 25.97%, 46.67%, 27.36%, 49.3% and 50.7%, respectively, the CC genotype or C allele in EH patients had significantly higher frequencies than controls [41.60% vs. 27.36%, and 62.2% vs. 50.7%, respectively (P<0.05)]. It was also shown that TGF- beta 1 +869 C allele carriers had significantly increased risk of EH compared with T allele carriers (OR=1.60, P=0.00). There was linkage disequilibrium (LD) between the two polymorphisms. The frequency of haplotype C-G in the EH group was significantly higher than that in controls (61.6% vs. 49.8%, P<0.05). There were no differences in TGF- beta 1 level among different genotypes or alleles in both +869T/C and +915G/C loci (P>0.05).
Conclusion: The frequency of +915G/C variation of the TGF- beta 1 gene was very low in Kazakh and there was no homozygous variation. The +869 C allele was likely the genetic susceptibility factor for EH in the population. There was linkage disequilibrium in the polymorphisms of +869T/C and +915G/C. Haplotype C-G was the risk factor of EH.