RPE degeneration predisposes photoreceptor cells to secondary damage and death consequent to the loss of support from the RPE and thus causes vision-threatening diseases such as dry age-related macular degeneration (dry AMD) [2,3] and gyrate atrophy with hyperornithinemia .
Although there are no reports about the mode of RPE cell death in human gyrate atrophy with hyperornithinemia, necrosis of RPE cell was observed in ornithine-induced retinopathy in rats .
Moreover, spermidine might be involved in the pathogenesis of gyrate atrophy with hyperornithinemia, as spermidine is an ornithine metabolite .
Some specific diseases were confined to Arabs from Northern Oman such as MSUD (17/17), BPD-PKU (3/3), some urea cycle defects [ASA (4/6) hyperornithinemia
(2/2), Citrullinemia (3/3), OTC deficiency (2/2)], VLCAD (3/3), HMG-CoA lyase deficiency (9/9), CPT-I deficiency (5/5), and 3-Methylglutaconic aciduria (2/2).
Hyperammonemia can result from hepatic failure, enzymatic deficiencies of the urea cycle or defects in ornithine transport [e.g., HHH syndrome (hyperornithinemia
, hyperammonemia, hyperhomocitrullinuria)], or it may be secondary to other organic acidopathies (3).
This observation may be of clinical interest in conditions of hyperornithinemia. Decreased brain creatine has been observed in patients affected with gyrate atrophy of the choroid and retina (McKusick 258870).
Reduced brain creatine in gyrate atrophy of the choroid and retina with hyperornithinemia. Neurology 1999;53:303-7.
A positive allopurinol test has also been reported in the hyperornithinemia, hyperammonemia, and homocitrullinuria syndrome (6).
Argininemia; citrullinemia; argininosuccinic aciduria; lysinuric protein intolerance hyperornithinemia, hyperammonemia, and homocitrullinuria syndrome; and mitochondrial disorders were ruled out.