An association study of angiotensinogen polymorphisms with serum level and hypertension in an African-American population.
OBJECTIVE
To evaluate the association of angiotensinogen (AGT) gene with AGT level and hypertension based on the overall genetic variation of the AGT gene in among African-Americans.


METHODS
All non-rare single nucleotide polymorphisms (SNPs) in AGT were identified by resequencing 24 individuals. Five tagging SNPs were selected based on the pairwised linkage disequilibrium (LD) pattern and were genotyped in 284 individuals. Association studies of AGT level and hypertension were performed using these five tagging SNPs.


RESULTS
No significant association with AGT level or hypertension was found in analyses of each of the five single SNPs. However, one of the haplotypes defined by these five SNPs was significantly associated with AGT level (P = 0.046), although this haplotype was not associated with hypertension.


CONCLUSIONS
Identification of genetic polymorphisms associated with risk of hypertension has been frustratingly difficult. Two strategies adopted to improve precision are the use of intermediate phenotypes and summarization of genetic information using haplotypes. These strategies appeared to yield a modest increase in precision at the AGT locus with respect to the physiological intermediate, but did not lead to significant association of the molecular markers with hypertension. Additional research is required to increase confidence in haplotype mapping as an epidemiological analysis tool.
D000328:Adult; D001741:Black or African American / Q000235:genetics*; D000808:Angiotensinogen / Q000097:blood / Q000235:genetics*; D015992:Body Mass Index; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology; D006239:Haplotypes; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000208:ethnology* / Q000235:genetics*; D015810:Linkage Disequilibrium; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors
D000808:Angiotensinogen