Heterogeneity and complementation analysis of fibroblasts from vitamin B₆ responsive and non-responsive patients with gyrate atrophy of the choroid and retina

Fibroblasts from four pyridoxine responsive and three non-responsive patients with gyrate atrophy of the choroid and retina have been examined. Responsive patients had higher activity of ornithine ketoacid transaminase (OKT) in cell homogenates and greater incorporation of radioactivity from¹⁴C-ornithine into protein in cultured cells in situ compared to non-responsive patients. Complementation analysis of the cells from these seven patients was performed, based on the ratio of incorporation of¹⁴C/³H into protein in fused cells incubated in¹⁴C-ornithine and³H-leucine. Lack of positive complementation in these crosses suggests that pyridoxine responsive and non-responsive patients with gyrate atrophy represent different allelic mutations of the same genetic locus coding for OKT.