Genetic investigation by next generation sequencing of Primary Aldosteronism caused by Unilateral or Bilateral Adrenal Hyperplasia

Abstract

Primary Aldosteronism (PA) is the most common form of secondary AH with an estimated prevalence of approximately 4% in hypertensives treated in primary care services and 10% in patients referenced to tertiary hospitals. In the last decade, considerable advances have been made towards the better understanding of PA genetics. Somatic pathogenic variations in KCNJ5, CACNA1D, ATP1A1 and ATP2B3 genes, which are involved in maintaining intracellular ionic homeostasis and cell membrane potential, were described in 38%, 9.3%, 5.3% and 1.7% of tumors, respectively. Somatic activating variants in exon 3 of CTNNB1 gene, involved in the adrenocortical development, were identified in 3 tumors. Among familial PA, germlines defects in KCNJ5, CACNA1D and CACNA1H were identified in PA patients diagnosed before 10 years of age. In addition, pathogenic variants of CACNA1D were described in 2 cases of diffuse Unilateral Adrenal Hyperplasia, increasing the spectrum of lesions associated with CACN1AD mutations. However, genetic factors involved in the pathogenesis of PA caused by Unilateral and Bilateral Adrenal Hyperplasia in adults remais poorly elucidated. The aims of this study are: 1) to investigate somatic variants in KCNJ5, ATP1A1, ATP2B3 and CTNNB1 genes in unilateral or Bilateral Adrenal Hyperplasia from PA patients; 2) to perform exome sequencing (paired blood and tissue) of negative cases for pathogenic allelic variants in the KCNJ5, ATP1A1, ATP2B3 and CTNNB1 genes; 3) to validate and conduct functional studies of novel genetic variants found in the exome sequencing; 4) to evaluate the anatomopathological characteristics of adrenal lesions and investigate the immunoreactivity for CYP11B2 and CYP11B1. The following methodologies will be employed: automated SANGER sequencing, next-generation sequencing with subsequent bioinformatic analysis and immunohistochemistry. Here, we expect to identify new genes involved in the molecular pathogenesis of PA caused by Unilateral or Bilateral Hyperplasia. (AU)