[Hereditary phaeochromocytoma in twins]

Area of Science:

• Endocrinology
• Oncology
• Genetics

Background:

• Phaeochromocytoma, a tumor of adrenal gland's catecholamine-producing cells, can be sporadic or hereditary, with 25-30% linked to genetic mutations.
• Hereditary phaeochromocytomas/paragangliomas are increasingly diagnosed due to advances in genetic testing and gene discovery.

Observation:

• A 47-year-old female presented with bilateral adrenal gland enlargement, diagnosed as bilateral phaeochromocytomas via imaging and biochemical tests.
• Her genetically identical twin sister was also diagnosed with bilateral phaeochromocytoma, indicating a potential genetic cause.

Findings:

• Germline mutation in the transmembrane protein 127 (TMEM127) tumor suppressor gene was confirmed in both twins.
• Both underwent successful cortical-sparing adrenalectomy, with normalized hormone levels post-surgery.
• While one twin had no adrenal insufficiency, the other required glucocorticoid replacement therapy.

Implications:

• This is the first reported case of phaeochromocytoma affecting identical twins, underscoring the role of TMEM127 mutations in hereditary forms.
• Genetic screening in affected families revealed the mutation present across four generations.
• The findings emphasize the importance of genetic counseling and testing for phaeochromocytoma diagnosis and familial risk assessment.