MEN1 is an autosomal dominant endocrine tumour syndrome, caused by inactivating mutations of the MEN1 tumour suppressor gene at 11q13 locus and characterised by occurrence of hyperparathyroidism, pancreatic tumours and pituitary adenomas. We describe a family with MEN1 syndrome. The index case was a 71-year-old man, referred to Endocrinology clinic in Midland Regional Hospital Portlaoise for hypercalcemia (calcium 3 mmol/l, phosphate 0.5 mmol/l, PTH 350 pg/ml, creatinine 120 μmol/l) and diagnosed with primary hyperparathyroidism (PHPT). He was treated with cinacalcet for hypercalcaemia as he had multiple comorbidities such as ischaemic heart disease with a history of coronary artery bypass grafting and prosthetic aortic valve replacement, heart failure, chronic obstructive pulmonary disease and abdominal aortic aneurysm. CT thorax for respiratory symptoms demonstrated a bulky pancreas with a 4×3 cm heterogenous lesion in the pancreatic tail. Due to the presence of PHPT and the pancreatic lesion, he underwent MEN1 genetic testing. In the meantime, his eldest son presented at 40 years with hypercalcaemia due to PHPT (calcium 3.29 mmol/l, phosphate 0.75 mmol/l, PTH 174 pg/ml). He was referred to St. Vincents University Hospital neuroendocrine multidisciplinary clinic and underwent subtotal parathyroidectomy, which showed parathyroid adenoma on histology. On screening, he had a non-functioning pituitary macroadenoma which was resected, bilateral adrenal adenomas with low-grade hypercortisolism and pancreatic neuroendocrine tumours (pNETs). The second son also presented with hypercalcaemia secondary to PHPT. On further screening, he had pNETs but no evidence of pituitary tumour or adrenal lesions. Genetic testing of all three patients revealed a heterozygous mutation in MEN1 gene, Exon 9, c.1348C>T, pGln405Ter. In conclusion, this report of MEN1 family highlights the phenotypic variability of MEN1 syndrome within one family having the same MEN1 gene mutation. Careful phenotyping of patients with PHPT can reveal additional diagnoses of endocrine tumours.
18 - 21 May 2019
European Society of Endocrinology