Pyridoxine effects on ornithine ketoacid transaminase activity in fibroblasts from carriers of two forms of gyrate atrophy of the choroid and retina.
Gyrate atrophy of the choroid and retina that is due to ornithine ketoacid transaminase (OKT) deficiency is an autosomal recessive disorder. Fibroblasts from heterozygotes for the pyridoxine-responsive variant as well as those for the pyridoxine-nonresponsive variant contain intermediate levels of OKT activity. These two variants can be distinguished by the in vitro responsiveness of OKT activity to pyridoxal phosphate (PLP) stimulation. The ratios of OKT activity at 0.04 mM PLP compared with activity at 0 mM PLP were, respectively, lowest for controls (1.18 +/- 0.18; N = 12), intermediate for pyridoxine-nonresponsive heterozygotes (1.43 +/- 0.26; N = 5), and highest for pyridoxine-responsive heterozygotes (2.20 +/- 0.14; N = 3).
Shih
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Amino Acid Disorder Laboratory, Massachusetts General Hospital, Boston 02114.
Mandell
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Berson
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D001284:Atrophy; D002460:Cell Line; D002829:Choroid / Q000473:pathology*; D004795:Enzyme Stability; D005347:Fibroblasts / Q000201:enzymology; D006579:Heterozygote; D006801:Humans; D009953:Ornithine-Oxo-Acid Transaminase / Q000172:deficiency* / Q000235:genetics; D011736:Pyridoxine / Q000494:pharmacology*; D012162:Retinal Degeneration / Q000235:genetics* / Q000473:pathology; D000637:Transaminases / Q000172:deficiency*; D014603:Uveal Diseases / Q000201:enzymology / Q000235:genetics
D000637:Transaminases; D009953:Ornithine-Oxo-Acid Transaminase; D011736:Pyridoxine