Different Somatic Mutations in Multinodular Adrenals With Aldosterone-Producing Adenoma

Abstract

Primary aldosteronism is the most common form of secondary hypertension. Somatic mutations in KCNJ5, ATP1A1, ATP2B3, and CACNA1D are found in aldosterone-producing adenoma. In addition, adrenals with aldosterone-producing adenomas show cortical remodeling and frequently multiple secondary nodules. Our aim was to investigate whether different aldosterone-producing nodules from the same adrenal share the same mutational status. Aldosterone synthase expression was assessed in multinodular adrenals from 27 patients. DNA of 37 aldosterone-producing secondary nodules was extracted from formalin-fixed paraffin-embedded tissues and genotyped for KCNJ5, ATP1A1, ATP2B3, and CACNA1D mutations. Among 17 adrenals with a somatic mutation in the principal nodule, 4 showed the same mutation in a secondary nodule, whereas 10 had no mutation in any of the known genes. In 1 adrenal harboring the KCNJ5 p.Gly151Arg mutation in the principal nodule, the same mutation was present in 2 secondary nodules, but no mutation was found in a third nodule. Finally, in 2 adrenals with a CACNA1D mutation in the principal nodule, a KCNJ5 mutation was identified in the secondary nodule. Among 10 adrenals without mutations in the principal nodule, 1 carried a KCNJ5 mutation in the secondary nodule. No mutations were detected in 7 aldosterone-producing cell clusters from 6 adrenals. No association was observed between the presence of mutations in secondary nodules and clinical parameters. In conclusion, different mutations are found in different aldosterone-producing nodules from the same adrenal, suggesting that somatic mutations are independent events triggered by mechanisms that remain to be identified.

Keywords: adrenal cortex; aldosterone; hyperaldosteronism; mineralocorticoids; mutation; potassium channels.

Figure 1. Immunohistochemical features of multinodular adrenal glands

A. HES staining and aldosterone synthase IHC of an adrenal gland resected for lateralized PA showing an APA and secondary micronodules. Left. HES staining with the identification of secondary nodules in an adrenal carrying an APA. Right. Aldosterone synthase IHC positive in one secondary adrenal nodule. B. HES staining (upper panels) and CYP11B2 ISH (bottom panels) in an adrenal carrying an APA and one APCC region.

Figure 2. Genotyping of secondary nodules identified in adrenals with APA. A. Adrenal 1

Left and middle panels: Sanger sequencing chromatograms showing the KCNJ5 mutation c.451G>A in APA and the wild type KCNJ5 sequence in the secondary nodule. Right panel: ddPCR analysis showing the amount of wild type G allele and mutant A allele of the KCNJ5 mutation c.451G>A in the secondary nodule. B. Adrenal 26. Left panels: Sanger sequencing chromatograms showing the KCNJ5 mutation c.451G>C in APA and the wild type KCNJ5 sequence in the secondary nodule. Right panels: ddPCR analysis showing the amount of wild type G allele and mutant A allele (c.451G>A) and the amount of wild type G allele and mutant C allele (c.451G>C) in the secondary nodule. C. Adrenal 15. Left and middle panels: Sanger sequencing chromatograms showing the wild type KCNJ5 sequence in APA, the CACNA1D mutation c.2293C>T in APA, and the KCNJ5 mutation c.451G>A in the secondary nodule. Right panel: ddPCR analysis showing the amount of wild type G allele and mutant A allele of the KCNJ5 mutation c.451G>A in the secondary nodule. D. Adrenal 24. Left and middle panels: Sanger sequencing chromatograms showing the wild type KCNJ5 sequence in APA, the CACNA1D mutation c.2293C>T in APA, and the KCNJ5 mutation c.1207G>C in the secondary nodule. Right panel: ddPCR analysis showing the amount of wild type G allele and mutant A allele of the KCNJ5 mutation c.451G>A in the secondary nodule. E. Adrenal 4. Left and middle panels: Sanger sequencing chromatograms showing the wild type KCNJ5 sequence in APA and the KCNJ5 mutation c.451G>A in the secondary nodule. Right panel: ddPCR analysis showing the amount of wild type G allele and mutant A allele of the KCNJ5 mutation c.451G>A in the secondary nodule.