A Novel Case of Somatic KCNJ5 Mutation in Pediatric-Onset Aldosterone-Producing Adenoma

Primary aldosteronism caused by a pI157S somatic KCNJ5 mutation in a black adolescent female with aldosterone-producing adenoma

Aldosterone-producing adenoma is a rare cause of hypertension in children. Only a limited number of cases of aldosterone-producing adenomas with somatic KCNJ5 gene mutations have been described in children. Blacks are particularly more susceptible to developing long-standing cardiovascular effects of aldosterone-induced severe hypertension. Somatic CACNA1D gene mutations are particularly more prevalent in black males whereas KCNJ5 gene mutations are most frequently present in black females. We present here a novel somatic KCNJ5 p.I157S mutation in an aldosterone-producing adenoma from a 16-year-old black female whose severe drug-resistant hypertension significantly improved following unilateral adrenalectomy. Prompt diagnosis of aldosterone-producing adenoma and early identification of gene mutation would enable appropriate therapy and significantly reduce cardiovascular sequelae.

Genetic and epigenetic analyses of aldosterone-producing adenoma with hypercortisolemia

DNA methylation is associated with excess cortisol and aldosterone. The DNA encoding aldosterone synthase (CYP11B2) and 11β-hydroxylase (CYP11B1), which catalyzes the final step of cortisol biosynthesis, is less methylated in aldosterone-producing adenomas (APA) and cortisol-producing adenomas (CPA), respectively. Several studies have reported specific gene mutations in APA and CPA, and some APAs also cause hypercortisolemia. The aim of this study was to clarify the molecular mechanisms of cortisol co-production in APA using genetic and epigenetic analyses. We evaluated 16 patients with APA between 2011 and 2018 at Kanazawa University Hospital (Ishikawa, Japan). The diagnostic criteria for hypercortisolemia were based on the guideline from the Endocrine Society. Gene mutation and DNA methylation analyses of the CYP11B2 and CYP11B1 promoters in APA were performed. Of the 16 patients with APA, six also had hypercortisolemia. In the genetic analysis, all six APAs with hypercortisolemia as well as eight of the 10 APAs without hypercortisolemia had a KCNJ5 mutation. In the epigenetic analyses, the methylation status of the CYP11B2 promoter was similar in the APAs with and without hypercortisolemia. However, in the APAs with hypercortisolemia, the CYP11B1 promoter was significantly less methylated, especially at two CpG sites near the Ad1/cAMP response element binding site within the CYP11B1 promoter. In conclusion, the genetic analysis revealed no association between hypercortisolemia and the evaluated gene mutations. However, the epigenetic analysis suggested that DNA methylation of the CYP11B1 promoter plays a role in concurrent hypercortisolemia and APA.

Expression of aldosterone synthase CYP11B2 was inversely correlated with longevity

Immunohistochemistry of human aldosterone synthase (CYP11B2) has revealed that most of aldosterone is autonomously produced in aldosterone-producing cell clusters (APCCs) beneath the capsule of adult adrenals rather than physiologically in the zona glomerulosa (ZG). APCCs have been occasionally found to harbor a somatic mutation of ion channel/pump genes, and number and size of APCCs increase with age until 50 years old. Herein, the objective of the study was to examine APCC development in 106 autopsied adrenals from 85 elderly individuals who died at ages from 50 to 103 years. We obtained the following results: (1) physiological CYP11B2 expression in ZG were attenuated in more elderly persons; (2) number and size of APCCs decreased with age; (3) detachment of APCC from the capsule appeared to occur occasionally over the wide range of the ages; and (4) incidental micro aldosterone-producing adenomas (APAs) and possible APCC-to-APA transitional lesions (pAATLs) were found primarily in samples from persons aged 50-60 years but not in samples from more elderly persons; pAATL was a putative designation based on our previous results indicating that it consisted of subcapsular APCC-like portion and inner APA-like portions. Thus, the formation of the CYP11B2-expressing lesions as well as thickening of the ZG in the adrenals were inversely correlated with age of death in the individuals aged over 50 years. Considering that autopsy samples were used in this study, inactive production of aldosterone regardless of autonomous or physiological manners may have survival advantages in individuals aged over 50 years.