PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Gyrate atrophy”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1992

A single-base change at a splice acceptor site in the ornithine aminotransferase gene causes abnormal RNA splicing in gyrate atrophy.

Gyrate atrophy (GA) is an autosomal recessive eye disease involving a progressive loss of vision due to chorioretinal degeneration in which the mitochondrial matrix enzyme ornithine aminotransferase (OAT) is defective. Two sisters with GA are described in this study in whom an A-to-G substitution at the 3' splice acceptor site of intron 4 in one allele of the OAT gene results in a truncated OAT mRNA devoid of exon 5 sequence. The mutation in the other allele was identified to be a mis-sense mutation at codon 318 by denaturing gradient gel electrophoresis and direct sequencing of the polymerase chain reaction (PCR)-amplified DNA. Thus, these GA patients are compound heterozygotes with respect to mutations in the OAT gene that result in inactivation of OAT.

Adenine↗
PubMed1990

Splicing defect at the ornithine aminotransferase (OAT) locus in gyrate atrophy.

Gyrate atrophy (GA), a recessive eye disease involving progressive vision loss due to chorioretinal degeneration, is associated with the deficiency of the mitochondrial enzyme ornithine aminotransferase (OAT), with consequent hyperornithinemia. We and others have reported a number of missense mutations at the OAT locus which result in GA. Here we report a GA patient of Danish/Swedish ancestry in whom one OAT allele produces an mRNA that is missing a single 96-bp exon relative to the normal mRNA. Polymerase-chain-reaction amplification and sequencing revealed a 9-bp deletion covering the splice acceptor region of exon 5, resulting in the absence of exon 5 sequences from the mRNA with no disruption to the reading frame. This mutation, which was not present in 15 other independent GA patients, adds to the array of allelic heterogeneity observed in GA and represents the first example of a splicing mutation associated with this disorder.

Adult↗
PubMed1992

A 15-bp deletion in exon 5 of the ornithine aminotransferase (OAT) locus associated with gyrate atrophy.

Gyrate atrophy of the choroid and retina (GA) is an autosomal recessive disorder in which a deficiency of the mitochondrial matrix enzyme ornithine aminotransferase (OAT) leads to progressive blindness. Previously, we and others have reported a number of missense mutations and splice defects in the OAT gene associated with GA. In the present case, through sequencing of the PCR amplified cDNA products, we have detected a novel 15-bp deletion within exon 5 of the OAT gene which retains the original reading frame. The deleted PCR product is the only one produced from the patient's mRNA, while mRNA from the patient's mother yields both deleted and normal length PCR products. The alternate, apparently nonexpressing OAT allele in this patient was inherited from the father, who displays only the normal length PCR product. The codon at the deletion joint remains unaltered, predicting the loss of the pentapeptide Tyr-Thr-Val-Lys-Gly without any other amino acid change. The breakpoints are adjacent to or within two copies of a 4-bp direct repeat, which may have implications for the mechanism of deletion.

Amino Acid Sequence↗
PubMed1992

A deletion in the ornithine aminotransferase gene in gyrate atrophy.

Gyrate atrophy (GA) is an autosomal recessive chorioretinal degenerative disease of the eye caused by an inborn defect of the nuclear encoded mitochondrial enzyme ornithine aminotransferase (OAT). We have described previously a GA patient with a 5.0-kilobase pair truncated EcoRI OAT gene fragment and the absence of OAT mRNA on Northern blot analysis. Cloning and sequencing analysis of the truncated gene fragment revealed a 1,072-base pair (bp) deletion including the entire exon 6, starting in intron 5, 172 bp upstream of exon 6 and ending in intron 6, 772 bp downstream of exon 6. A short direct repeat sequence (AGGAGC), resembling the sequence shown to cause DNA polymerase alpha to pause, and sequences capable of forming hairpin loops were both present at the 5' and 3' break-points of the deletion. Reverse transcription-polymerase chain reaction amplification of the patient's RNA with OAT primers yielded DNA fragments of two different sizes, consistent with a low level expression of OAT mRNA. Direct sequencing of the smaller fragment demonstrated the complete absence of exon 6 sequence in the mRNA predicted from the deletion, causing a reading frame shift which results in a premature termination codon at position 192. The mutation in the other allele has been demonstrated by polymerase chain reaction, denaturing gradient gel electrophoresis, and direct sequencing also to be a premature termination codon in exon 6. The absence of detectable OAT mRNA in this patient is consistent with these premature termination mutations because they have been shown to decrease the level of mRNA, especially if present early in the coding sequence.

Amino Acid Sequence↗
PubMed1988

Molecular basis of ornithine aminotransferase deficiency in B-6-responsive and -nonresponsive forms of gyrate atrophy.

Gyrate atrophy (GA), a recessive eye disease involving progressive loss of vision due to chorioretinal degeneration, is associated with a deficiency of the mitochondrial enzyme ornithine aminotransferase (OATase; ornithine-oxo-acid aminotransferase; L-ornithine:2-oxo-acid aminotransferase, EC 2.6.1.13) with consequent hyperornithinemia. Genetic heterogeneity of GA has been suggested by the demonstration that administration of pyridoxine to increase the level of pyridoxal phosphate, a cofactor of OATase, reduces hyperornithinemia in a subset of patients. We have cloned and sequenced cDNAs for OATase from two GA patients, one responsive and one nonresponsive to pyridoxine treatment. The respective cDNAs contained different single missense mutations, which were sufficient to eliminate OATase activity when each cDNA was tested in a eukaryotic expression system. However, like the enzyme in fibroblasts from the pyridoxine-responsive patient, OATase encoded by the corresponding cDNA from this individual showed a significant increase in activity when assayed in the presence of an increased pyridoxal phosphate concentration. These data firmly establish that both pyridoxine responsive and nonresponsive forms of GA result from mutations in the OATase structural gene. Moreover, they provide a molecular characterization of the primary lesion in a pyridoxine-responsive genetic disorder.

Cloning, Molecular↗
PubMed1980

Inhibition of arginine-glycine amidinotransferase by ornithine. A possible mechanism for the muscular and chorioretinal atrophies in gyrate atrophy of the choroid and retina with hyperornithinemia.

The inhibitory effect of ornithine on L-arginine:glycine amidinotransferase (EC 2.1.4.1) was studied in crude rat kidney homogenates. The enzyme activity was linear with time up to 45 min and with protein up to 200 microgram. The apparent Km and V of amidinotransferase were 9.21 mM and 1.53 mu mol/g protein per min, respectively. The enzyme was competitively inhibited by ornithine, with a Ki of 0.253 mM. Kidney arginase was inhibited only slightly and non-competitively. The inhibition of amidinotransferase by ornithine may thus be important in creatine biosynthesis. In gyrate atrophy of the choroid and retina with hyperornithinemia, a human autosomal recessive disease caused by decreased ornithine aminotransferase activity, plasma ornithine concentrations are elevated 10-20-fold (0.65-1.35 mM during fasting). In consequence endogenous creatine production probably is severely decreased because of inhibition of the rate-limiting transamidination step by ornithine. The deficiency of creatine and further of readily available energy in the form of phosphocreatine is suggested to be involved in the pathogenesis of the choroidal, retinal and type II muscle fiver atrophies in gyrate atrophy.

Amidinotransferases↗
PubMedDate not supplied

Differential diagnosis of diffuse choroidal atrophies. Diffuse choriocapillaris atrophy, choroideremia, and gyrate atrophy of the choroid and retina.

Three young children showed a similar fundus appearance of sharply defined, yellowish-white, patchy or geographic atrophy of the retina and choroid and visible large choroidal vessels in almost the entire fundus. Fluorescein angiography disclosed atrophy of the retinal pigment epithelium and loss of choriocapillaris. Their visual functions and electrophysiologic findings were also similar. Family A was diagnosed as having diffuse choriocapillaris atrophy with autosomal dominant inheritance; family B, choroideremia with X-linked recessive heredity; and family C, gyrate atrophy of the choroid and retina with hyperornithinemia and autosomal recessive transmission. It became evident that diffuse choriocapillaris atrophy, choroideremia, and gyrate atrophy sometimes show a similar fundus appearance. Fluorescein angiography, serum ornithine levels, and family history were particularly helpful to differentiate these diffuse choroidal atrophies.

Adolescent↗
PubMed1992

Expression of human ornithine aminotransferase (OAT) in OAT-deficient Chinese hamster ovary cells and fibroblasts of gyrate atrophy patient.

Gyrate atrophy is a hereditary chorioretinal degenerative disease caused by a deficiency of the mitochondrial enzyme, ornithine aminotransferase (OAT). Recent investigations have demonstrated the molecular genetic defects of OAT in gyrate atrophy patients. We constructed a eukaryotic expression vector (pcDHOAT) which contains the SV40 promoter and human OAT cDNA. We used OAT(-) Chinese hamster ovary (CHO) cells, which have negligible OAT activity, and fibroblasts from a gyrate atrophy patient (GA35 cell), which have negligible OAT mRNA and enzyme. Incorporation of pcDHOAT and synthesis of human OAT mRNAs and active enzyme were demonstrated in both cell types. The level of expression of human OAT was low in the GA35 cells in comparison to the CHO cells. Despite the limited success, the ability to express active OAT in these OAT-deficient cells using an expression vector offers possibilities of replacement gene therapy for gyrate atrophy.

Animals↗
PubMed1997

Retrovirus-mediated gene transfer of ornithine-delta-aminotransferase into keratinocytes from gyrate atrophy patients.

Gyrate atrophy is a progressive blindness associated with deficiency of ornithine aminotransferase (OAT). The strategy of using an autologous keratinocyte graft, modified to express high levels of OAT as an ornithine-catabolizing skin-based enzyme sink, is investigated. Two OAT-containing retroviral vectors were constructed with or without a resistance gene. When packaged in a retroviral vector particle generated with the gibbon ape leukemia (GALV) virus envelope (PG13), these vectors could readily transduce >50% of target keratinocytes. The transduced keratinocytes in culture expressed up to 75-fold more OAT than normal control keratinocytes and these gene-modified cells extracted [14C]ornithine more efficiently than controls. The vector prepared without neo transduced cells more efficiently and led to higher levels of OAT expression than the neo-containing vector. Ornithine catabolism was maintained at high levels when the transduced patient keratinocytes were differentiated in vitro as a multilayered cutaneous organoid.

3T3 Cells↗
PubMed2000

Possible role of polyamines in gyrate atrophy.

PURPOSE: Gyrate atrophy (GA) is marked by hyperornithinemia and lowered ornithine amino transferase (OAT). However there are patients of GA without hyperornithinemia and those with hyperornithinemia without GA. Some cases of GA have been reported to have low lysine. The purpose of the study was to determine if polyamines, the metabolites of ornithine, and lysine have any diagnostic role in GA. METHODS: Ornithine in plasma was estimated by two-dimensional paper chromatography, with elution of the coloured spot, and the absorbance measured using a spectrophotometer at 560 nm. OAT assay in lymphocytes was done spectrophotometrically using ornithine as substrate. Blood and urinary polyamines were extracted with n-butanol, benzoylated and analysed with HPLC; putrescine, spermine, spermidine, and cadaverine were assayed individually at 254 nm with the UV detector using ODS, G18 column with 63% methanol as solvent. RESULTS: Of the 7 patients investigated, 6 had features typical of GA. One was diagnosed to have atypical retinitis pigmentosa (case 3). The first five cases had elevated ornithine and diminished OAT, but cases 6 and 7 had near-normal ornithine and case 7 had near-normal OAT. However, all 7 patients had increased levels of total polyamines in urine compared to normals. Five had increased putrescine and three had increased spermine. All the 7 had decreased cadaverine in urine. Thus, though there were inconsistencies with ornithine and OAT, all the 7 patients had elevated polyamines from ornithine and decreased cadaverine. CONCLUSION: In addition to estimating ornithine and OAT in GA, it is suggested that urinary polyamines may be analysed as the latter appears to correlate better with the clinical condition and help in the diagnosis to a greater extent. Moreover, while ornithine is an innocuous amino acid, polyamines are known to damage DNA and proteins.

Adolescent↗
PubMed1986

Differential diagnosis of normoornithinaemic gyrate atrophy of the choroid and retina.

A case of localized chorioretinal atrophy resembling gyrate atrophy of the choroid and retina is presented. Plasma ornithine concentration was normal and the clinical course characterized by late onset of relatively mild symptoms. The differential diagnoses are discussed and the term normoornithinaemic gyrate atrophy of the choroid and retina is suggested for similar variant cases.

Aged↗
PubMed1999

Creatine corrects muscle 31P spectrum in gyrate atrophy with hyperornithinaemia.

BACKGROUND: Eye fundus destruction and type II muscle fiber atrophy in gyrate atrophy of the choroid and retina with hyperornithinaemia (GA) may be mediated by elevated ornithine concentrations which strongly inhibit creatine biosynthesis. This results in deficiency of creatine phosphate (PCr), a key intracellular energy source, as we have demonstrated in skeletal muscle of the patients by 31P magnetic resonance spectroscopy (31P MRS). MATERIALS AND METHODS: Possible correction of the relative PCr deficiency by long-term daily exogenous supplementation of creatine or its precursors was investigated in four GA patients receiving creatine and in five patients treated with guanidinoacetic acid-methionine combination. The relative PCr concentration, expressed as PCr/Pi (Pi; inorganic phosphate) or as PCr/ATP ratios, was compared with the values of untreated GA patients, and matched healthy volunteers. RESULTS: Muscle PCr/Pi ratios (mean +/- SD) of the untreated and creatine supplemented GA patients and controls were 4.9 +/- 1.4, 7.9 +/- 0.4 and 8.4 +/- 1.3. Guanidinoacetate-methionine combination was similarly effective (respective PCr/Pi ratios: 4.9 +/- 0.7, 6.3 +/- 1.1 and 10.7 +/- 2.8). CONCLUSION: Supplementation with creatine or creatine precursors almost normalised low muscle PCr/Pi ratios of patients with GA.

Adolescent↗
PubMedDate not supplied

Gyrate atrophy of the choroid and retina.

Gyrate atrophy of the choroid and retina is characterized by autosomal recessive inheritance, progressive chorioretinal atrophy beginning in late childhood, and hyperornithinemia with ornithinuria caused by deficient ornithine aminotransferase activity. In this paper, four patients with gyrate atrophy are described. All patients had visual impairment, mental retardation, hyperornithinemia, hypolysinemia, ornithinuria and lysinuria. The first case had hypermetropic astigmatism in contrast to other reported gyrate atrophies. These are the first reported cases from Turkey, but gyrate atrophy may not be rare in Turkey since the frequency of some other metabolic disorders has also been reported to be high. It is suggested that gyrate atrophy must be considered in all patients with chorioretinal atrophy.

Adolescent↗
PubMed2001

[Gyrate atrophy of late disclosure].

Gyrate atrophy of the choroid and retina is a chorioretinal degeneration caused by a deficiency of ornithine aminotransferase. We report the case of a 29-year-old woman who showed an advanced stage of gyrate atrophy of the choroid and retina fortuitously discovered. Examination of the patient provided an opportunity to describe pathophysiology, knowledge on the ornithine aminotransferase gene, and finally the therapeutics used in this disease.

Adult↗
PubMed2002

Gyrate atrophy of choroid and retina.

Gyrate atrophy of choroid and retina is a rare disorder of autosomal recessive nature. There occurs patchy and progressive atrophy of the choroid and retina at the equatorial region with central area being less affected. Here in this case report, one woman of about 47 years attended at the retina clinic, Tenennt Institute of Ophthalmology, Glasgow University with the history of gradual loss of vision. On fundus examination, sharply defined bizarre shaped atrophic areas of fundus was seen in both the eyes. Velvet like fine granular pigments were present in the macula, the zone of healthy retina and the periphery. The colourless, elongated, glittering crystals were scattered over the dark brown pigments visible through 90 dioptre lens. Bone corpuscles pigments were not found. Fluorescein angiography showed hyperfluorescence in the area of gyrate atrophy. Her plasma ornithine level and plasma tiramine level were 1 90 U mol/l and 357 U mol/l. respectively. A rigid schedule of low protein diet including near total elimination of arginine with supplementation of essential amino acids was advised since the diagnosis was established.

Choroid Diseases↗
PubMed2006

Osteoporosis associated with gyrate atrophy: a case report.

Gyrate atrophy (GA) is a rare degenerative, hereditary disease characterized by markedly high serum ornithine levels resulting from the deficiency of ornithine-delta-amino transferase (OAT), a mitochondrial matrix enzyme. Hyperornithinaemia is accompanied by lysinuria and reduced lysine plasma levels in GA. Type I collagen is known to play a role in osteoporosis pathogenesis. Lysine has a role in cross ligament formation of type I collagen, a bone matrix element, and thus, in bone strength. Although the most common complaint in GA is visual problems, the disease may include muscle involvement, as well. Reduced physical activity resulting from muscle involvement and hypolysinemia in GA may lead to osteoporosis. However, there is no data in the literature concerning the relation between GA and osteoporosis. In this report a GA case with early osteoporosis, besides visual deterioration and muscular signs, is reported, and the relation between GA and osteoporosis is emphasized for the first time.

Adult↗
PubMed1979

Gyrate atrophy of the choroid and retina with hyperornithinemia: tubular aggregates and type 2 fiber atrophy in muscle.

We studied 21 patients with gyrate atrophy of the choroid and retina and hyperornithinemia. Although the patients were not weak, type 2 muscle fibers were almost universally atrophic and had tubular aggregates. Gyrate atrophy is the first disease in which females are shown to have tubular aggregates; the sexes were affected equally. In gyrate atrophy the number of type 2 fibers decreases with age. The muscle and eye changes are probably related to abnormal creatine synthesis, caused, in gyrate atrophy, by the increased body pool of ornithine; muscle abnormalities may also be present in other tapetoretinal dystrophies.

Adolescent↗