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A specific enzyme defect in gyrate atrophy.

To establish the enzyme defect in gyrate atrophy, we measured the activity of ornithine aminotransferase in phytohemagglutinin stimulated lymphocytes in a patient with gyrate atrophy, her daughter, and three normal controls. The patient's cells had no detectable ornithine aminotransferase activity and the daughter's cells had 44% of control activity. This intermediate value is characteristic of an obligate heterozygote. These results are the first demonstration of an enzyme defect in gyrate atrophy.

Adult↗

Colour vision in gyrate atrophy.

A follow-up study of colour vision in two patients with gyrate atrophy was performed. Gyrate atrophy was diagnosed in the first patient at the age of 17 years. Her colour vision was first tested at the age of 25 years; at the follow-up examination 7 years later, she correctly interpreted the Standard Pseudoisochromatic Plates part 2, however, with one mistake due to lens opacity. In the Farnsworth-Munsell 100 hue test and in the Color Vision Meter 712 (CVM) anomaloscope, the results were within normal ranges. In the second patient, gyrate atrophy was diagnosed at the age of 4 years. At the ages of 4 and 5 years, he correctly interpreted the Ishihara, AO H-R-R, and Lanthony Tritan Album plates as well as the City University test. At the ages of 6, 7, and 8 years, he correctly interpreted the plate tests, the Farnsworth Panel D 15, and Lanthony's Desaturated Panel. The CVM anomaloscope results were normal.

Adult↗

Retinal boundaries and visual function in gyrate atrophy.

Three patients with gyrate atrophy of the retina and choroid underwent fundus photoperimetry, the combination of fundus photography and visual field analysis within the same instrument, to examine the correspondence between the funduscopically observed, scalloped margin of remaining retina and the functional limit of the peripheral visual field. The results suggest that near the border between remaining retina and atrophic areas, visual sensitivity falls off quite rapidly, producing perimetric isopters that conform closely to the scalloped retinal margin. In some instances, visual function can be demonstrated in islands of remaining retina that are totally surrounded by atrophic areas. This study demonstrates the usefulness of fundus photoperimetry in following the course of degenerative retinal diseases.

Adult↗

A two year trial of low protein, low arginine diets or vitamin B6 for patients with gyrate atrophy.

Four patients with gyrate atrophy on low protein (20-35 g/day), low arginine diets and one on vitamin B6 (300 mgm/day) have maintained their plasma ornithine concentrations in the range of 30-60% of pre-therapeutic trial levels for about two years. After two years, three of the five patients have shown no significant change in Snellen visual acuity, visual fields, final dark-adapted thresholds or full-field electroretinograms. All five patients have shown slight enlargement of areas of chorioretinal atrophy in the midperiphery. These patients continue on low protein, low arginine diets or on vitamin B6 to determine whether any reduction in the hyperornithinemia will result in stabilization of retinal function.

Adolescent↗

Pathology of iridectomy specimens in gyrate atrophy of the retina and choroid.

Gyrate atrophy of the retina and choroid is an autosomal recessive disease characterized by progressive retinal degeneration and ornithine aminotransferase deficiency. We report here the new histological findings and ultrastructural changes in 3 iridectomy specimens from 2 Finnish patients with gyrate atrophy. The iridectomy specimens were removed during routine cataract extraction and studied with a transmission electron microscope. The dilator muscle showed atrophy, abnormal mitochondria, and tubular aggregate type structures similar to those found in skeletal muscle. Degenerative changes such as extracted cellular matrix, dropout of cellular organelles, and dilated intercellular spaces were observed in the pigmented posterior epithelium and the anterior iris epithelium.

Adult↗

Association of thyroid disease with retinitis pigmentosa and gyrate atrophy.

PURPOSE: To compare the prevalence of thyroid disease in patients with retinitis pigmentosa, in patients with gyrate atrophy of the choroid and retina, and in patients with no history of ocular disease. METHOD: Forty-four patients with retinitis pigmentosa, 34 patients with gyrate atrophy, and 30 normal control patients with no ocular disease were evaluated in a case-control study for the presence of thyroid disease. RESULTS: Thyroid disease was diagnosed in six of 44 patients with retinitis pigmentosa and seven of 34 patients with gyrate atrophy but in only one of 30 control patients. Compared with control patients, the odds ratio for the occurrence of thyroid disease was 6.2 for patients with retinitis pigmentosa and 12.7 for patients with gyrate atrophy. CONCLUSION: These data suggest an increased occurrence of thyroid disease in patients with retinitis pigmentosa and gyrate atrophy.

Adolescent↗

Ornithine ketoacid transaminase deficiency in gyrate atrophy of the choroid and retina.

Gyrate atrophy of the choroid and retina is a chorioretinal degeneration associated with hyperornithinemia with an autosomal recessive mode of inheritance. Cultured skin fibroblasts from five affected patients showed a virtual absence of ornithine ketoacid transaminase (OKT) (L-ornithine:2-oxoacid aminotransferase E.C.2.6.1.13) activity. Fibroblasts from four carrier parents showed a 42%-65% reduction in OKT activity. Increasing the concentration of pyridoxal phosphate (vitamin B6 in the assay media resulted in partial restoration of OKT activity in fibroblasts from one out of five patients studied. We conclude that OKT deficiency is closely associated with the genetic defect in gyrate atrophy of the choroid and retina and that genetic heterogeneity exists in this disease.

Adolescent↗

Clinical trials of vitamin B6 and proline supplementation for gyrate atrophy of the choroid and retina.

Five patients with gyrate atrophy of the choroid and retina were examined ophthalmologically, especially ophthalmoscopically, to evaluate trials of vitamin B6 (pyridoxine) or supplementary proline. The oral administration of vitamin B6 was tried in two patients. The vitamin did not alter the serum ornithine level and the progression of chorioretinal atrophy in one patient (case 2). Despite a reduced serum ornithine level following vitamin B6 administration, chorioretinal atrophy progressed gradually in another patient (case 3). Supplementary proline was tried in four patients. Despite the supplementation the serum proline level did not increase, and the chorioretinal atrophy progressed in one patient (case 2) who received both vitamin B6 and proline. Supplementary proline minimised the progression of gyrate atrophy in the youngest patient (case 1) and halted the progression in two others (cases 4 and 5). Supplementary proline may possibly lessen the progression of chorioretinal lesions in gyrate atrophy.

Adolescent↗

Gyrate atrophy of the choroid and retina with hyperornithinaemia, cystinuria and lysinuria.

The case of a 45-year-old woman with gyrate atrophy of the choroid and retina is documented. Additional features in this case, to the authors' knowledge not previously described in gyrate atrophy, are massive cystinuria, massive lysinuria, axial hypermetropia and diabetes. Gyrate atrophy is a rare autosomal recessive degenerative disease of the choroid and retina and is accompanied by defective ornithine metabolism. Simell and Takki demonstrated the association with hyperornithinaemia in 1973. The main metabolic features are those of hyperornithinaemia and ornithuria caused by a deficiency of the mitochondrial matrix enzyme, ornithine aminotransferase (OAT). The responsible human gene has been localised to chromosome 10. Despite the generalised deficiency of OAT, the literature indicates significant pathological involvement of the eye only. Ophthalmological features of the disease are myopia (up to 10-20 dioptres), night blindness, constricted visual fields and complicated cataracts. The clinical picture has been detailed previously by various authors. The case of a 45-year-old woman with gyrate atrophy and hyperornithinaemia is documented here. She has been followed up for 12 years and fully investigated. Additional features in this case, to our knowledge not previously described in gyrate atrophy, are massive cystinuria, massive lysinuria, axial hypermetropia and diabetes.

Adult↗

Bilateral late posterior chamber intraocular lens dislocation with the capsular bag in a patient with gyrate atrophy.

A pseudophakic patient with gyrate atrophy of the choroid and retina presented with bilateral intraocular lens (IOL) dislocation with the capsular bag several years after uneventful cataract surgery. The patient had not performed strenuous physical activity. One IOL was initially repositioned by nonsurgical manipulations, while the other required surgical repositioning. Eventually, IOL exchange was performed successfully in both eyes.

Adult↗

Anterior subcapsular plaque cataract in hyperornithinaemia gyrate atrophy--a case report.

Hyperornithinaemia gyrate atrophy (HOGA) is a rare autosomal recessive disorder in which chorioretinal degeneration occurs with cataracts, myopia, and hyperornithinaemia. We report the case of an 18-year-old female who presented with the typical features of HOGA, including posterior subcapsular cataracts and elevated plasma ornithine. She later developed distorted vision in both eyes owing to wrinkling of the anterior lens capsules. Histological examination following lens extraction showed the wrinkling was caused by focal distortion from capsular fibrosis (anterior subcapsular plaque cataract). This specific lens change has not been linked previously with HOGA.

Adolescent↗

Genotype-phenotype correlation of a pyridoxine-responsive form of gyrate atrophy.

Two clinical subtypes of gyrate atrophy (GA) have been defined based on in vivo or in vitro evidence of response to vitamin B6 (pyridoxine), which is the cofactor of the enzyme ornithine aminotransferase (OAT) shown to be defective in GA. We identified the E318K mutation in the OAT gene, heterozygously in three patients and homozygously in one patient, all of whom were vitamin B6-responsive by previous in vivo and in vitro studies. Dose-dependent effects of the E318K mutation were observed in the homo- and heterozygotes in the OAT activity, increase of OAT activity in the presence of pyridoxal phosphate, and apparent Km for pyridoxal phosphate. The highest residual level of OAT activity and mildness of clinical disease correlated directly with the dose of the mutant E318K allele present in the patient.

Amino Acid Sequence↗

Investigation of gyrate atrophy using a cDNA clone for human ornithine aminotransferase.

Gyrate atrophy of the choroid and retina is an autosomal recessive disease associated with reduced or absent ornithine aminotransferase (OAT) activity. To approach the defect in OAT at the molecular level, we have cloned a cDNA for the mRNA encoding the OAT precursor from human liver. The clone contains the complete coding region of 1317 nucleotides along with 44 nucleotides of 5' and 654 nucleotides of 3' untranslated sequences. When used to probe genomic DNA, the OAT cDNA did not detect any evidence of gene deletion or rearrangement in patients with gyrate atrophy. The cDNA hybridizes to a 2.15-kb RNA species in liver, fibroblasts, and lymphoblasts. The size and approximate amount of this mRNA is not altered in fibroblasts and/or lymphoblasts of seven gyrate atrophy patients who display a 25- to 100-fold reduction in OAT activity. Our results suggest the defect in these individuals may be caused by a subtle sequence alteration in the mRNA that does not affect its apparent size.

Base Sequence↗

Low-protein diet and progression of retinal degeneration in gyrate atrophy of the choroid and retina: a twenty-six-year follow-up.

Gyrate atrophy of the choroid and retina is an autosomal recessive chorioretinal dystrophy which leads to a slowly progressive loss of vision. The primary defect is due to a deficiency of the enzyme ornithine delta-aminotransferase, which is responsible for markedly elevated levels of ornithine in plasma and other body fluids. Although several therapeutic regimens have been proposed, the reduction in ornithine accumulation obtained by reducing the intake of its precursor arginine (semisynthetic low-arginine diet) is the one most practised. In this clinical and molecular study we report a patient with hyperornithinaemia and gyrate atrophy of the choroid and retina who had been diagnosed when she was 3 years 9 months old. She also presented mild mental retardation, delayed language development and speech defects. The patient has recently been found to be homozygous for the new Gly91Arg amino acid substitution of the enzyme ornithine delta-aminotransferase. This mutation lies in a region of the mature protein that is considered crucial for the mitochondrial targeting activity. In this patient, a 28-year treatment with a completely natural low-protein diet (0.8 g/kg per day of natural protein) has been able to significantly reduce ornithine plasma levels, and to greatly delay the natural progression of the chorioretinal changes. This study suggests that, in the long-term treatment of gyrate atrophy, the efficacy in slowing the progression of chorioretinal changes and the palatability of a completely natural low-protein diet make this treatment a potentially viable alternative in patients refusing the semisynthetic diet.

Adult↗

[Gyrate atrophy of the choroid and retina: a case report].

BACKGROUND: Gyrate atrophy of the retina and choroid is a rare disease, with recessive autosomal transmission, characterized by progressive chorioretinal atrophy causing blindness. It results from a congenital deficit in aminotransferase ornithine. CASE REPORT: The authors present the case of a young patient aged 15 years old consulting for a progressive fall of visual acuity with hemeralopia. Eye funduscopy showed regions of confluent rounded chorioretinal atrophy. The visual field, the electroretinogram and the retinal angiography were all alterated. Gyrate atrophy of the retina and choroid was evocated. DISCUSSION: It is a systemic and rare metabolic disease where ocular features are dominating. Differencial diagnosis are pigmentary retinopathies. Cataract and/or myopia are often joined to the retinal lesions. General signs could consist in muscular weakness, thin and rare hairs and mental retardation. More than; visual fields, electroretinogram, retinal angiography that are alterated; the plasmatic dosage of the ornithine is often high. The treatment is based on the dietetics with uncertain results. The genic therapy would be the treatment of future.

Adolescent↗

Gyrate atrophy of the choroid and retina.

A rare case of gyrate atrophy of the choroid and retina is reported in two female siblings. The diagnosis was made on clinical, electrophysiological, angiographic and biochemical features. This possibly is the first documentation of hyperornithemic gyrate atrophy (HOGA) from the Indian subcontinent.

Child↗

Gyrate atrophy of the choroid and retina. Long-term reduction of ornithine slows retinal degeneration.

Gyrate atrophy of the choroid and retina is an autosomal recessive, chorioretinal dystrophy that begins in childhood and leads to blindness in the fourth to seventh decade of life. The primary defect is deficiency of ornithine-delta-amino-transferase, which results in accumulation of ornithine. We examined six pairs of affected siblings to determine if intrafamilial variability in the phenotype was less than interfamilial, and to determine if long-term (5- to 7-year) reduction of ornithine with an arginine-restricted diet had an effect on the progression of the chorioretinal degeneration. All but one set of siblings underwent periodic ophthalmologic examinations. The clinical diagnosis was confirmed with the demonstration of hyperornithinemia and deficiency of ornithine-delta-aminotransferase. The molecular defects in their ornithine-delta-amino-transferase genes also were determined. The two younger pairs of siblings were given an arginine-restricted diet and followed up for 5 to 7 years. We found strikingly similar phenotypes in affected members of the same pair of siblings. In the young patients receiving the diet, there was substantial reduction of ornithine levels. These children had only modest progression of their ocular disease during this period. Furthermore, a comparison of the outcome of the younger with their older siblings at an equivalent age showed that the younger siblings, who started receiving the diet at an earlier age, had much less ocular disease. We conclude that intrafamilial phenotypic variation in gyrate atrophy is less than interfamilial and, therefore, that genetic heterogeneity plays a role in the phenotypic variability of gyrate atrophy. Furthermore, we conclude that chronic reduction of ornithine with an arginine-restricted diet dramatically slows the progression of the chorioretinal dystrophy.

Adult↗

[Gyrate atrophy with macular dystrophy].

In a case of gyrate atrophy with hyperornithinemia a macular dystrophy was found. The ERG amplitude was markedly decreased whereas the b-wave implicit time was found to be normal. There was an obvious parallel between the extent of the peripheral and central alterations of the retina in both eyes. It may be assumed that in this case of gyrate atrophy the remaining retinal areas suffered little damage as far as qualitative parameters are concerned. Macular dystrophy may be one form of manifestation of the underlying disease.

Adult↗