Analysis of the metallothionein gene in age-related macular degeneration

Purpose: To analyze the expression of metallothionein in neovascular membranes in patients with age-related macular degeneration (AMD) and to compare the findings in patients with proliferative diabetic retinopathy and proliferative vitreoretinopathy with findings in normal retinal pigment epithelial (RPE) cells. Methods: Semiquantitative reverse transcriptase-polymerase chain reaction and immunohistochemical examinations were performed. Sequence analysis was also carried out. Results: Expression of the metallothionein-II gene was not statistically significant in proliferative membranes. Sequence analysis revealed that there were at least six polymorphisms in the metallothionein-II gene and three in the metallothionein-IA gene. However, no amino acid substitution was observed. Metallothionein expression was also observed by immunohistochemical techniques in RPE cells of neovascular membranes in AMD patients. Conclusions: Metallothionein was reported to be decreased in aged macular RPE and in some monkey retina with early onset of macular degeneration. However, our results suggest that the expression of the metallothionein-II gene in neovascular membranes in patients with AMD may be controlled like other proliferating cells. Jpn J Ophthalmol 2000;44:115-121 (C) 2000 Japanese Ophthalmological Society.