Patient’s Atypical Cushing’s Symptoms Lead to Discovery of Novel Genetic Mutations

New genetic mutations were found in a patient who exhibited atypical symptoms of Cushing’s syndrome, notably an abnormal protrusion of the eye, a case report shows.

The research, “Extensive ARMC5 genetic variance in primary bilateral macronodular adrenal hyperplasia that started with exophthalmos: a case report,” was published in the Journal of Medical Case Reports.

Primary bilateral macronodular adrenal hyperplasia (PBMAH) is a disorder characterized by multiple lumps in the adrenal glands and excessive cortisol production. It is a rare cause of Cushing’s syndrome.

According to recent research, PBMAH is caused by mutations in the ARMC5 gene, which data suggest may act as a tumor suppressor.

Researchers presented the case of a 52-year-old Chinese woman who exhibited a protrusion of both eyes (exophtalmos), which was first thought to be Graves’ ophthalmopathy. An injection of triamcinolone acetonide, a corticosteroid, into the area behind the eye globe did not improve symptoms.

The patient later was diagnosed with diabetes, which was treated with insulin, and hypertension, treated with insulin and amlodipine. She also developed muscle weakness and bruised easily. She had no other relevant chronic illness or infectious disease, and did not smoke tobacco or drink alcohol.

Physical examination showed skin atrophy, moon face, buffalo hump (between the shoulders), and purplish abdominal striae (stretch marks), which researchers defined as a typical Cushingoid appearance. The patient also experienced elevated pressure inside the eye, and had edema, conjunctival congestion, and lid retraction. No liver, spleen, respiration, cardiac, abdominal, blood counts, urinary, sensory, or motor abnormalities were noted.

Biochemical evaluation showed elevated cortisol and reduced adrenocorticotropin (ACTH) levels. Administering  dexamethasone did not lower the level of cortisol. Abnormal responses of the hormone vasopressin also were detected.

A computed tomography (CT) scan of the adrenal glands showed bilateral multiple lobular masses, and an MRI of the eye orbits indicated bilateral exophthalmos with hypertrophy of the retro-orbital fat, which lines the orbit.

After PBMAH was diagnosed, the patient’s adrenal glands were removed. Pathological findings showed multiple, homogenous, golden-yellow-colored nodules on the glands.

The surgery successfully lowered the level of cortisol and increased that of ACTH. The patient began taking hydrocortisone and metformin for diabetes. After six months, her exophtlamos, blood glucose levels, and blood pressure had improved.

Genetic analysis revealed six specific ARMC5 mutations in five of the seven adrenal nodules analyzed. “All the mutations are novel and not found in available online databases,” the researchers wrote. The mutations may lead to resistance to cell death in the tumor cells, and cause an increase in the production of cortisol, they observed.

As a result of the ARMC5 mutations, gene expression (conversion of genetic information) of the messenger RNA (mRNA, which is converted from DNA in the first step of protein synthesis) was lower in the adrenal tumor samples, in comparison with normal adrenal cortex.

Overall, the study “highlights the importance of early recognition of atypical symptoms of Cushing’s syndrome such as exophthalmos, which would save the patient from harmful effects of excessive cortisol exposure,” the researchers said. Screening for ARMC5 mutations also would help improve diagnosis and genetic counseling, they said.