Haplotype analysis of aldosterone synthase gene (CYP11B2) polymorphisms shows association with essential hypertension Natasha N. Kumar a , Adam V. Benjafield a , Ruby C.Y. Lin a , William Y.S. Wang b , Michael Stowasser c and Brian J. Morris a Objective The CYP11B2 locus is an important candidate region in essential hypertension (HT). We therefore investigated CYP11B2 polymorphisms T2344C, T4986C and A6547G for association with essential HT. This included haplotype analysis and measurement of plasma aldosterone levels. Methods The three single nucleotide polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis of genomic DNA from 146 HT and 291 normotensive (NT) white subjects of Anglo-Celtic descent, in whom parental blood pressure status was the same as the subjects’. Genotype and allele frequencies in HTs and NTs were compared by ÷ 2 analysis. Linkage disequilibrium and haplotype frequencies were estimated by the program ‘snphap’. Phenotype–genotype relationships were tested using one-way analysis of variance. Results The T2344C variant was associated with HT (÷ 2 7.4, P 0.0064). This association was confined to female HTs (P 0.0061 for genotypes, P 0.0013 for alleles). A strong association with HT was also seen for the A6547G variant (P 0.0015), being greatest in females (P < 0.0001). No association was seen for the T4986C variant. Haplotype analysis of the three single nucleotide polymorphisms across eight different haplotype combinations showed a significant association with HT (÷ 2 24, seven degrees of freedom, P < 0.001). No significant tracking of plasma aldosterone with genotype was observed. Conclusion The T2344C and A6547G, but not the T4986C, variants of the aldosterone synthase gene are associated with HT in females of the Anglo-Celtic population studied. This was reinforced by haplotype analysis. J Hypertens 21:1331–1337 & 2003 Lippincott Williams & Wilkins. Journal of Hypertension 2003, 21:1331–1337 Keywords: case–control study, haplotype analysis, aldosterone synthase, Anglo-Celtic, restriction fragment length polymorphism, polymorphism, hypertension, molecular genetics a Basic & Clinical Genomics Laboratory, Department of Physiology, School of Medical Sciences, and Institute for Biomedical Research, The University of Sydney, Sydney, Australia, b Department of Medical Genetics, University of Cambridge, UK and c Hypertension Unit, University of Queensland Department of Medicine, Princess Alexandra Hospital, Brisbane, Australia. Sponsorship: This research was supported by a grant from the National Health and Medical Research Council of Australia. Correspondence and requests for reprints to Professor B. J. Morris, Basic & Clinical Genomics Laboratory, Department of Physiology, School of Medical Sciences and Institute of Biomedical Research, Building F13, The University of Sydney, NSW 2006, Australia. Tel: +61 2 9351 3688; fax: +61 2 9351 2227; e-mail: brianm@physiol.usyd.edu.au Received 9 January 2003 Revised 25 March 2003 Accepted 28 March 2003 See editorial commentary page Introduction Aldosterone is an independent risk factor for cardio- vascular disease [1]. Aldosterone synthase (CYP11B2) catalyzes the final step in aldosterone biosynthesis and could therefore influence blood pressure (BP). The CYP11B2 locus (chromosome 8q22) is present in tandem with the locus for CYP11B1, which is involved in cortisol synthesis, but can influence aldosterone [2]. CYP11B2 is thus an obvious gene to test for association with hyper- tension (HT) [3]. A number of such studies has been conducted [4–19], but the results have been conflicting. These studies used subjects of various ethnicities (French, Caucasian, African American, Japanese), and differences in the genetic contribution of particular variants between racial/ethnic groups is probable [20]. Moreover, because of the close proximity of the CYP11B1 and CYP11B2 loci, any result for a polymorphism in one of these genes might reflect involvement of the other, as a result of linkage disequilibrium (LD) between particu- lar variants across these loci. It is also of interest that the CYP11B1/2 locus has been implicated in the rare Mendelian form of HT, glucocorticoid remediable aldos- teronism, which is associated with abnormalities in mineralocorticoid metabolism. Moreover, a common in- tron 2 conversion variant of CYP11B2 may also contribute to high blood pressure in HTs [10,21]. In the present study we tested three variants of Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Original article 1331 0263-6352 & 2003 Lippincott Williams & Wilkins DOI: 10.1097/01.hjh.0000059078.43904.bf