Untying the Next Genetic Thread in a Family With MEN2A Syndrome: A Case Report.

Multiple endocrine neoplasia type 2A (MEN2A) is a rare autosomal dominant syndrome characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, and primary hyperparathyroidism. Early genetic screening is crucial for timely intervention. We report a familial case of MEN2A involving four affected members across two generations. The index patient, a 40-year-old male with prior MTC and pheochromocytoma, presented with recurrent adrenal disease. His 41-year-old sister was diagnosed with MTC and pheochromocytoma despite negative genetic testing. The youngest sibling (37 years) and the index patient's 18-year-old son were diagnosed with MTC, with the former testing positive for a RET mutation. All underwent appropriate surgeries with ongoing surveillance. This case highlights the variable clinical presentation and genetic penetrance of MEN2A within a single family. It underscores the importance of genetic screening in all MTC patients and their first-degree relatives, as early identification of asymptomatic carriers enables timely prophylactic interventions.