MON-209 Identification of a New Heterozygous Germline ARMC5 Deletion in a Familial Case of Primary Bilateral Macronodular Adrenal Hyperplasia Co-Secreting Cortisol and Aldosterone

Abstract Context. Approximately 50% of familial cases of primary bilateral macronodular adrenal hyperplasia (PBMAH) are caused by mutations in the ARMC5 gene. Case report. We report the case of a 37 year-old patient of Haitian origin, who presented with resistant hypertension. His workup showed high aldosterone (410 pmol/L) with suppressed renin levels (0.2 ng/mL/h) with an aldosterone to renin ratio (ARR) of 2050. Patient also had suppressed ACTH levels (<0.5 pmol/L (N: 2-12)) and high UFC (1103 nmol/d (N: <330)). He had an aberrant cortisol and aldosterone response to catecholamines and vasopressin (V1R). An abdominal CT scan showed bilateral enlargement of adrenal glands and a 3.3cm dominant nodule on the right gland. Moreover, a 2.8cm mass on the pancreatic tail was present. Patient underwent left laparoscopic adrenalectomy and distal pancreatectomy; the pathology confirmed PBMAH and a pancreatic neuroendocrine tumor (NET). Following surgery, ARR and UFC remained high and patient was treated successfully with B-blockers and MR antagonists. A head MRI showed no sign of intracranial meningiomas. Genetic analyses. Following genetic counselling, MEN1 gene analysis was performed using sequencing/MLPA techniques but did not reveal a mutation. Initial genetic testing included ARMC5 gene analysis using direct Sanger sequencing which was negative. However, using Next-Generation Sequencing (NGS) and MLPA analysis, a heterozygous germline ARMC5 deletion of exons 5-8 was identified. The deletion is predicted to prematurely truncate the protein product and cause loss of function. The ARMC5 deletion segregated with the disease in his 24 yo son who had bilateral adrenal adenomas that appeared to be non-functional. The patient’s father was also known for having bilateral adrenal masses and hypertension. To our knowledge we report the second case of ARMC5 deletion in familial PBMAH. Suzuki et al. reported two patients, a mother and her son, carrying ARMC5 deletion of exons1-5 and interestingly they were also affected by PBMAH co-secreting cortisol and aldosterone (1). As in this case report, the ARMC5 deletion was missed using Sanger sequencing initially. Conclusion. These cases demonstrate that large deletions may be missed by Sanger sequencing and that the real prevalence of ARMC5 mutations may have been underestimated. The link between deletion of ARMC5 and correlation with PBMAH co-secreting aldosterone and cortisol remains to be determined but may be a step forward for genotype-phenotype correlation. 1.Suzuki S, et al. Endocrine practice: official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists. 2015;21 (10):1152-60.

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