Different polymorphisms of the mineralocorticoid receptor gene are associated with either glucocorticoid or mineralocorticoid levels in hypertension.
OBJECTIVE
Both aldosterone and cortisol can activate the mineralocorticoid receptor (MR). Polymorphisms in the MR gene have been inconsistently shown to be associated with risk of hypertension and aldosterone and cortisol levels. The purpose of this project was to investigate the association of MR gene variants with serum aldosterone and a previously identified hypertension subgroup with higher urinary free cortisol (UFC) levels (high-mode UFC) in a rigorously phenotyped Caucasian hypertensive cohort.


METHODS
A haplotype-based tagging single nucleotide polymorphism (htSNP) association study was conducted in the HyperPATH cohort of 570 hypertensive Caucasian subjects on a salt-controlled diet. Haplotypes generated from 74 htSNP representing the common genetic variations of the entire MR gene were analyzed by comparing high- vs. normal-mode UFC groups and the association with serum aldosterone levels.


RESULTS
Of the observed 20 haplotype blocks, there were three main linkage disequilibrium (LD) regions with high recombination rates between adjacent regions. Overlaying gene structure on this LD map revealed that block 1-8 corresponded to exon 5-9 [ligand binding domain (LBD)], blocks 9-18 to exon 3-4 [DNA binding domain (DBD)], and block 19-20 to exon 1-2 (N-terminal domain). Haplotype association results showed that DBD-aligned LD blocks were associated with high-mode UFC status (global P values, 0.0004 to 0.05). The LBD-aligned LD blocks showed significant associations with serum aldosterone levels.


CONCLUSIONS
These findings imply that there may be differential functional importance of the DBD and LBD of the MR in the regulation of glucocorticoid and aldosterone levels in hypertensive subjects.
Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital and Harvard Medical School, 221 Longwood Avenue, Boston, Massachusetts 02115, USA.
Bei
B
Sun
Bindu
B
Chamarthi
Jonathan S
JS
Williams
Alexander W
AW
Krug
Jessica
J
Lasky-Su
Benjamin A
BA
Raby
Paul N
PN
Hopkins
Xavier
X
Jeunemaitre
Claudio
C
Ferri
Gordon H
GH
Williams
D000328:Adult; D000450:Aldosterone / Q000097:blood; D004247:DNA / Q000235:genetics; D005091:Exons / Q000235:genetics; D005260:Female; D005838:Genotype; D005938:Glucocorticoids / Q000378:metabolism*; D006239:Haplotypes; D006801:Humans; D006854:Hydrocortisone / Q000652:urine; D006973:Hypertension / Q000235:genetics* / Q000378:metabolism*; D015810:Linkage Disequilibrium / Q000235:genetics; D008297:Male; D008901:Mineralocorticoids / Q000378:metabolism*; D020641:Polymorphism, Single Nucleotide; D017419:Potassium, Dietary / Q000494:pharmacology; D018161:Receptors, Mineralocorticoid / Q000235:genetics*; D012982:Sodium, Dietary / Q000494:pharmacology; D044465:White People
D005938:Glucocorticoids; D008901:Mineralocorticoids; D017419:Potassium, Dietary; D018161:Receptors, Mineralocorticoid; D012982:Sodium, Dietary; D000450:Aldosterone; D004247:DNA; D006854:Hydrocortisone