Abstract
Studies on excised aldosterone-producing lesions have found somatic mutations in five genes (KCNJ5, CACNA1D, ATP1A1, ATP2B3, and CTNNB1) commonly causes the excess aldosterone production. Interestingly, Oriental cohorts had the highest frequency of KCNJ5 mutations whereas CACNA1D mutations were most common in Black African Caribbean patients, suggesting that genetic background affects the prevalence and distribution of aldosterone-driving somatic mutation. We therefore aimed to identify the common germline variants that associates with excess aldosterone production through performing a pilot genome wide association study (GWAS) on primary aldosteronism (PA) patients. GWAS was performed using the Human Infinium OmniExpressExome-8 v1.4 BeadChip containing 960,919 markers to compare gDNA of 154 PA patients with 78 healthy controls. Samples were checked for sex discordance, heterozygosity rate, missing rate and the degree of recent shared ancestry for each pair of individuals using the PLINK program and Genome Studio (Illumina). In total, 150 patients and 75 controls (112 males and 113 females) were included in the downstream analysis. 630,749 markers that passed quality control steps (missing call rate <95% and minor allele frequency in controls >1%) were used to perform association analysis using the Chi-square Test which was then subjected to multiple testing corrections (Bonferroni correction). As expected with a pilot sample size, no variants passed the suggestive significant threshold of Bonferroni corrected P-value < 5 x 10-6 (-log10 P = 5.3). However, 27 SNPs had the uncorrected P-value<0.0002, odds ratio >2, and differences of frequencies in cases compared to control >0.1 or <-0.2, of which 3 genes (SRGAP3, AUTS2, and RORA) associated with these SNPs were also highlighted in the UK Biobank database of 72 patients with primary aldosteronism (https://biobankengine.stanford. edu/coding/HC189). Of these, RORA has recently been found to be down-regulated in adrenals from PA patients and spontaneously hypertensive rat adrenals compared to control adrenalsa,b. RORA encodes for the protein retinoic acid receptor (RAR)-related orphan receptor alpha, a member of the NR1 subfamily of nuclear hormone receptors (NR1F1). Interestingly, adrenal is the second organ to skin with the highest expression of RORA and treatment of angiotensin II in the adrenocortical cell line H295R increases RORA expressionc,d. Taken together, this pilot GWAS highlights RORA as a potential nuclear hormone receptor that regulates aldosterone production.
References
aChu et al., Int J Clin Exp Pathol 2017;10(9):10009-10018. bTanaka et al., Hypertens Res 2019;42(2):165-173. cNogueira et al., Mol Cell Endocrinol 2009; 302(2): 230–236. dGTEx Analysis Release V7 (dbGaP Accession phs000424.v7.p2)
Acknowledgements
This research was supported by the Malaysian Ministry of Higher Education Grant (FRGS/1/2015/SKK08/UKM/02/3), The National University of Malaysia (UKM) University Grant (GUP-2016-083), and The UKM Medical Center Fundamental Grant (FF-2016-302).
Recurrent gain of function mutation in calcium channel CACNA1H causes early-onset hypertension with primary aldosteronism
