Vitreous amyloidosis after liver transplantation in patients with familial amyloid polyneuropathy:: ocular synthesis of mutant transthyretin

Vitreous amyloidosis has bee reported in patients with familial amyloidotic polyneuropathy (FAP) who are carriers of different mutant transthyretins (TTR). The mutant TTR constitutes the majority of the amyloid vitreous fibrils in heterozygous Val30Met patients. Due to the ocular synthesis of TTR, it is possible that the retina constitutes the source of vitreous amyloid fibrils; if so, orthotopic liver transplantation (OLT) performed to remove the mutant TTR from circulation might not be effective in treating/avoiding vitreous amyloid. We present vitreous amyloidosis in a FAB patient from Maiorca with ATTR Val30Met who underwent OLT at age 38. Progressive impairment of visual acuity (VA) appeared bilaterally 2 years after OLT due to vitreous opacities consistent with amyloid; successful bilateral vitrectomy was performed. Amyloid was demonstrated in the vitrectomy material by Congo red staining; immunohistochemistry and Western blotting analyses were positive with an antibody for human TTR. Mass spectrometry of TTR revealed the presence of the mutant in approximately 20% of the TTR. Future structural studies on vitreous material with different proportions of normal/versus mutant TTR might shed some light on TTR fibrillogenesis. These results show that vitreous deposition of TTR amyloid fibrils occurs after OLT, suggesting that ongoing intraocular synthesis of mutant TTR might contribute to this process. We also present the progression after OLT of vitreous amyloidosis previously diagnosed in three patients with TTR Val71Ala.