Portuguese Man with FAP-related Glaucoma Treated Without Surgery, Case Study Shows
Researchers reported a rare case of a patient with type 1 familiar amyloid polyneuropathy (FAP) who went to the emergency room with pain in his right eye, and was diagnosed with a secondary type of glaucoma 14 years after a liver transplant.
The case study, “De novo intraocular amyloid deposition after hepatic transplantation in familial amyloidotic polyneuropathy,” was published in the journal World Journal of Transplantation.
The most common type of FAP, type 1, is an autosomal dominant disease. This means the patient inherits the faulty gene from a parent and that one copy of the defective gene is sufficient to cause the disease.
The TTR gene provides coding for an important protein, the transthyretin or TTR protein. This transport protein carries the thyroid hormone, called thyroxine, and retinol (vitamin A1) through the serum and cerebrospinal fluid to different parts of the body.
If the protein is defective, or when the sequence of the faulty protein is inaccurate, the TTR protein aggregates instead of disintegrating. The aggregates accumulate primarily in the peripheral nerves, gastrointestinal tract, the heart, ocular tissues, and other organs.
TTR is generally synthesized and secreted to the blood by the liver. However, it is also produced in the eyes (intra-ocular), but to a lesser degree.
Patients with FAP very often need a liver transplant to improve their quality of life and for long-term survival.
Even after a liver transplant, FAP patients can get ocular aggregations of TTR, because of persistent intra-ocular production of amyloid TTR.
These amyloid aggregates eventually cause FAP-related glaucoma. Glaucoma causes irreversible blindness if not detected in time and treated.
This study was a case report of a 42-year-old male Portuguese patient. He was diagnosed in 1995 with type 1 FAP, and received a liver transplant in 1997. His inital symptoms of glaucoma began appearing in 2011.
The patient underwent rigorous testing by the authors of the study. They diagnosed him with FAP-related,secondary open-angle glaucoma. Despite the diagnosis, the patient had 20/20 eyesight, the physicians said.
The patient showed ocular hypertension (40 mmHg in right eye and 28 mmHg in the left eye).
They also found scalloped pupils and TTR deposits in the pupils of the eyes, and observed mild vitreous opacities (in the liquid in the eyeball). This is a rare asymmetry, where the presence of the deposits are not spread around the eye, but are concentrated in the pupils.
This prompted the physicians to suggest that a part of the eye constitution, the ciliary pigment epithelium, is possibly involved in the synthesis of TTR in the eyes.
After their diagnosis, they treated the glaucoma using topical timolol and brimonidine treatment. After the therapy was applied, the patient’s normal eye pressure returned. Physicians continued this course of treatment until August of this year.
Until the study’s publication in August, the authors found no progression of glaucoma in the patient’s eyes.
“Early diagnosis is essential to avoid rapid progression of glaucoma” and to possibly reverse vision loss, the authors stated.
“The authors want to emphasize the importance of the recognition of ophthalmological signs that are associated with increased risk of ocular hypertension and glaucoma in FAP1 patients after [liver transplant].”