8401 Genetic Characterization of a Case of Primary Aldosteronism in an 11-Year-Old Girl carrying a Germline VUS of CACNA1H and a Somatic Mutation of CTNNB1

Abstract Disclosure: S. Parisien-La Salle: None. G. Van Vliet: None. G. Corbeil: None. M. Labrecque: None. M. Tétreault: None. I. Bourdeau: None. Introduction: Primary aldosteronism is a frequent cause of secondary hypertension in adults but is rare in children. We report the case and genetic studies of an 11 yo girl presenting with primary aldosteronism at puberty. Case presentation: An 11-year-old female patient was referred to the pediatric endocrinology clinic for hypertension (166/118). Her past medical history and family history were unremarkable. She reported polyuria, polydipsia and occasional headaches and abdominal pain. Her Tanner stage indicated that puberty was initiated (P2M2). An abdominal CT revealed a 9x10x11cm right adrenal mass with calcifications and a necrotic zone. On 18F-FDG PET/CT, the mass had an uptake of 2.9 SUVmax. Laboratory results revealed hypokalemia (K: 2.6 mmol/L N: 3.5-4.5) and elevated aldosterone (1712.8 pmol/L N: 110-1330) with suppressed renin (0.2 ng/ml/h N: 5.3). Her urinary aldosterone level was elevated (114 nmol/day N: 67). The rest of the biochemical adrenal panel was normal. Patient underwent a right adrenalectomy by laparotomy. The pathology report showed an adrenal tumor without capsular or vascular invasion. The only malignancy criterion was an area of necrosis and the ki-67% proliferation index was 1%. Genetic investigations: After informed consent, the patient underwent germline analysis for the chimeric gene CYP11B2/CYP11B1 (Ruhr University Bochum, Germany) and a multigene panel including KCNJ5, CACNA1D, CACNA1H and CLCN2 genes (Fulgent, CA), which were both negative except for a variant of unknown significance (VUS) that was identified in CACNA1H (c.3868GA, p.Val1290Ile) with a minor allele frequency of 3.291E-5 (GnomAD). Tumor DNA was extracted after adrenalectomy from fresh frozen tissues. Somatic genetic analysis of GNAS, CTNNB1, KCNJ5, ATP1A1, ATP2B3 and CACNA1D was performed using direct Sanger Sequencing (Genome Quebec Innovation Centre) and revealed a heterozygous missence pathogenic variant in the CTNNB1 gene (c.121 AG p.Thr41Ala). This mutation was absent in leukocyte DNA of the patient. Immunohistochemistry of the adrenal tumor disclosed strong cytoplasmic β-catenin staining in most tumor cells (monoclonal anti-β-catenin antibody; BD Transduction Laboratories). RNA-sequencing of patient tumor RNA was performed (Research Center CHU Québec) and compared to human adrenal total RNA (Clontech, Mountain View, CA). Pathway enrichment analysis showed activation of the Wnt signaling pathway. No variant was identified in GNAQ or GNA11 genes. However, GNRHR was upregulated compared to the control sample with a log2 fold change of 3.96 (p=0.000074). Conclusion: We present a rare pediatric case of an aldosterone producing adenoma harbouring a somatic β-catenin pathogenic variant with upregulation of GNRHR. The implication of the germline CACNA1H VUS still needs to be clarified. Presentation: 6/3/2024