A different amyloid formation mechanism: De novo oculoleptomeningeal amyloid deposits after liver transplantation

Background. Liver transplantation has served as a treatment for patients with familial amyloidotic polyneuropathy (FAP) because variant transthyretin (TTR), the pathogenic protein of FAP, is predominantly produced by the liver. However, the effect on amyloid formation of TTR that is synthesised by the retina and the choroid plexus remains to be elucidated in FAP patients with liver transplants. Objective. To investigate changes in ocular tissues and the central nervous system (CNS) of FAP patients after liver transplantation. Design. Clinical study. Setting. Graduate School of Medical Sciences, Kumamoto University, Japan. Intervention. Transplantation of livers from cadaveric or living donors. Measurements. Preoperative measures and postoperative (16-108 months) follow-up of clinical data, including routine ophthalmologic, neurologic, and laboratory evaluations. Results. In 22 patients with FAP related to the amyloidogenic TTR (ATTR) Val30Met and 3 patients with FAP ATTR Tyr114Cys, after liver transplantation, 3 patients began to show evidence of de novo glaucoma, and 1 had vitreous opacity that was caused by the variant TTR. Another three patients showed new amyloid deposits in the pupillary margin, which could lead to glaucoma and vitreous opacity. As for changes in the CNS and levels of total protein and TTR in cerebrospinal fluid (CSF), after liver transplantation, two FAP ATTR Tyr114Cys patients exhibited de novo amyloid deposition in the leptomeninges, and total protein and TTR levels in CSF were significantly increased. Conclusions. Oculoleptomeningeal involvement in FAP was not prevented by liver transplantation because variant TTR produced by the retina and the choroid plexus forms amyloid fibrils in situ.