A Vietnamese MEN2A syndrome patient with C634G germline mutation of the RET proto-oncogene

Abstract

Multiple endocrine neoplasia type 2A (MEN 2A) is a rare, autosomal dominant disease. It is characterized by complete penetrance of medullary thyroid carcinoma (MTC), lower prevalence of pheochromocytoma, hyperparathyroidism, and sometimes cutaneous lichen amyloidosis. Here, we reported a rare case of a 39-year-old man from Vietnam with pheochromocytoma as the first symptom of MEN 2A. An abdominal computed tomography (CT) revealed large, bilateral adrenal masses. Additional biochemical investigations presented a significant increase of both the urinary catecholamines and serum calcitonin. The patient then underwent a bilateral adrenalectomy, and histopathological examinations confirmed suspicions of MTC. Genetic testing indicated a nucleotide substitution located in exon 11 of the RET proto-oncogene (c.1900T > G, p.Cys634Gly), which was reported as a pathogenic mutation of MEN2A. Furthermore, this identical mutation was also detected in several family members of the patient. His sibling has the mutation, but was originally diagnosed with papillary thyroid carcinoma and had a total thyroidectomy. The mutation was also found in the patient's daughter and his sibling's daughter, which emphasizes their high risks of thyroid cancer. Therefore, this case in Vietnam draws attention to the importance of genetic counselling in C634G carriers, as well as strict follow-up appointments to reduce morbidity and mortality since the mutation is classified as a high-risk group within the MTC guidelines. Keywords: Multiple endocrine neoplasia 2A, Pheochromocytoma, RET proto-oncogene, Cys634Gly mutation