Genetic investigation of aldosterone-producing adrenocortical tumors by next generation sequencing

Abstract

Arterial hypertension (AH) is a major cardiovascular risk factor that affects 10% to 40% of the adult population in industrialized countries. Primary aldosteronism (PA) is the most common form of secondary hypertension with an estimated prevalence of approximately 10% in referred patients. In the last 5 years, considerable advances toward understanding of molecular genetics of aldosterone-producing tumors (aldosteronomas) have been made through the identification of mutations in ion-selective channels that regulate membrane potential. Somatic mutations in KCNJ5 gene, encoding the GIRK4 K+ channel, were identified in 38% of aldosteronomas. More recently, somatic mutations in ATP1A1 gene, encoding a ±1 subunit of Na+,K+-ATPase channel, and in the ATP2B3 gene, endoding a Ca+2-ATPase channel, were found in 5,3% and 1,7% of aldosteronomas, respectively. Additionally, mutations in CACNA1D gene, encoding a Ca+2 voltage-dependent channel, were demonstrated in 9,3% of aldosteronomas. Then, driven mutations were not identified in approximately 46% of aldosteronomas. The aims of our study are: 1) to investigate somatic mutations in KCNJ5, ATP1A1, ATP2B3 and CACNA1D genes in a Brazilian cohort of aldosteronomas; 2) To perform exome sequencing of negative aldosteronomas for KCNJ5, ATP1A1, ATP2B3 and CACNA1D mutations; 3) To correlate molecular findings with clinical patient data; 4) To validate the novel genetic variants by automated sequencing. To achieve these goals, we will employ the following tools: real-time quantitative PCR, automated SANGER sequencing and next-generation sequencing with bioinformatic analysis. We expect that this project will better characterize the spectrum of somatic mutations of Brazilian aldosteronomas and identify new genes involved with the pathogenesis of these tumors. (AU)