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PubMed This is a summary of 16 peer-reviewed journal articles Updated
Ophthalmology

Diagnostic Testing and Lab Reports

At a Glance

Gyrate Atrophy is diagnosed by combining a markedly high plasma ornithine level, disease-causing variants in both copies of the OAT gene, and eye tests such as ERG, OCT, and fundus autofluorescence to document retinal changes.

Confirming a diagnosis of Gyrate Atrophy requires a combination of biochemical blood tests, genetic sequencing, and advanced eye imaging. Because this condition is so rare, these tests provide the evidence needed to distinguish it from other retinal diseases and to create a baseline for tracking your or your child’s health over time.

Metabolic Testing: The Plasma Ornithine Test

The most immediate sign of Gyrate Atrophy is a significant elevation of an amino acid called ornithine in the blood.

  • Standard Thresholds: While a healthy person typically has plasma ornithine levels between 20 and 150 µmol/L (depending on the lab’s specific equipment, age, and treatment status), individuals with Gyrate Atrophy often show levels 10 to 20 times higher [1][2][3].
  • What to Look For: In many confirmed cases, ornithine levels range from 450 to over 1,200 µmol/L [4].
  • Exceptions: It is important to know that a single “normal” level doesn’t always rule out the condition by itself. In rare cases, such as in certain genetic variants or very young infants, levels might be lower [5][6].
  • Test Conditions: Follow the ordering laboratory’s collection instructions carefully. While some older guidelines suggested fasting, fasting is not universally required and prolonged fasting can be inappropriate and unsafe for children or those with metabolic conditions [7].

Genetic Testing: The OAT Gene

Genetic testing helps confirm the clinical picture, but it requires specialist interpretation. Gyrate Atrophy is caused by mutations in the OAT gene.

  • Biallelic Variants: To have the condition, a person must have biallelic mutations—meaning one “pathogenic” (disease-causing) mutation was inherited from each parent [8][9].
  • The Genetic Report: Your report might show two different mutations (compound heterozygous) or two identical mutations (homozygous). Be aware that a “Variant of Uncertain Significance” (VUS) does not definitively confirm disease. Furthermore, gene panels can occasionally miss copy-number or deep-intronic variants. If a test only finds one mutation but the symptoms and blood tests strongly suggest Gyrate Atrophy, your doctor may order additional specialized testing to find a “hidden” second mutation [10].

Ophthalmologic Imaging and Tests

While blood and gene tests look at the cause, eye tests look at the current state of the retina.

  • Electroretinogram (ERG): This test measures the electrical response of the eye’s light-sensing cells (rods and cones).
    • In early Gyrate Atrophy, the scotopic (rod/night vision) response often disappears first, followed by a weakening of the photopic (cone/color and detail) response [11].
    • In many diagnosed adults, the ERG is “non-recordable,” meaning the retina’s electrical activity is very low [12][10].
  • Optical Coherence Tomography (OCT): This is a non-invasive cross-section image of the retina. Doctors use it to look for:
    • Foveoschisis: A splitting of the retinal layers, which occurs in about 58% of eyes with Gyrate Atrophy [12][13].
    • Cystoid Macular Edema (CME): Tiny fluid-filled pockets in the center of the vision [14].
  • Fundus Autofluorescence (FAF): This imaging uses special light to see the health of the Retinal Pigment Epithelium (RPE). In Gyrate Atrophy, it reveals the classic “scalloped” atrophic patches as dark (hypoautofluorescent) areas [9][15]. Ultra-widefield FAF is particularly helpful because it can capture the far edges of the retina where the damage often begins [16].

By combining these results—the high ornithine levels, the OAT gene mutations, and the characteristic scalloped patterns on imaging—your care team can move forward with a clear and accurate diagnosis.

Common questions in this guide

What does a high plasma ornithine result mean?
A markedly elevated plasma ornithine level is a key clue to Gyrate Atrophy, and confirmed cases often have levels far above the laboratory reference range. A single normal result does not always exclude the condition, especially in some genetic variants or very young infants, so clinicians interpret it with the examination and other tests.
Does the ornithine blood test require fasting?
Fasting is not universally required for plasma ornithine testing, and prolonged fasting may be unsafe or inappropriate for children or people with metabolic conditions. Follow the collecting laboratory’s instructions and ask how the result compares with its age- and method-specific reference range.
What does finding two OAT gene mutations mean?
Gyrate Atrophy is usually confirmed when testing identifies disease-causing variants in both copies of the OAT gene, with one inherited from each parent. The two variants may be identical or different, while a variant of uncertain significance alone does not prove the diagnosis.
What happens if genetic testing finds only one OAT mutation?
If blood ornithine and eye findings strongly suggest Gyrate Atrophy, finding one OAT variant may not end the evaluation. A specialist may consider deletion and duplication analysis or other sequencing to look for a second variant that an initial panel missed.
What can ERG, OCT, and fundus autofluorescence show?
ERG measures electrical responses from rods and cones, and rod responses often become abnormal before cone responses. OCT can show foveoschisis or cystoid macular edema, while fundus autofluorescence can map scalloped areas of retinal pigment epithelium atrophy, including peripheral changes when widefield imaging is used.

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References

References (16)
  1. 1

    A possible ocular biomarker for response to hyperornithinemia in gyrate atrophy: the effect of pyridoxine, lysine, and arginine-restricted diet in a patient with advanced disease.

    da Palma MM, Ku C, Igelman AD, et al.

    Ophthalmic genetics 2023; (44(2)):191-197 doi:10.1080/13816810.2022.2098986.

    PMID: 35856163
  2. 2

    Metabolic follow-up of a Croatian patient with gyrate atrophy and a new mutation in the OAT gene: a case report.

    Zekušić M, Škaričić A, Fumić K, et al.

    Biochemia medica 2018; (28(3)):030801 doi:10.11613/BM.2018.030801.

    PMID: 30429681
  3. 3

    First report of c.425-1G>A mutation in ornithine aminotransferase gene causing gyrate atrophy of the choroid and retina with hyperornithinemia.

    Jalali H, Najafi M, Khoshaeen A, et al.

    European journal of ophthalmology 2021; (31(5)):NP23-NP26 doi:10.1177/1120672120921734.

    PMID: 32418451
  4. 4

    Clinical, biochemical and molecular analysis in a cohort of individuals with gyrate atrophy.

    Palmer E, Stepien KM, Campbell C, et al.

    Orphanet journal of rare diseases 2023; (18(1)):265 doi:10.1186/s13023-023-02840-0.

    PMID: 37667371
  5. 5

    Multimodal imaging and genetic screening in Mexican patients with Gyrate atrophy: identification of novel OAT pathogenic variants.

    Díazceballos-García AL, Matsui R, Chairez Miranda MG, et al.

    International ophthalmology 2024; (45(1)):1 doi:10.1007/s10792-024-03260-0.

    PMID: 39644342
  6. 6

    A neonate with ornithine aminotransferase deficiency; insights on the hyperammonemia-associated biochemical phenotype of gyrate atrophy.

    Kaczmarczyk A, Baker M, Diddle J, et al.

    Molecular genetics and metabolism reports 2022; (31()):100857 doi:10.1016/j.ymgmr.2022.100857.

    PMID: 35782604
  7. 7

    Novel Insights Into Gyrate Atrophy of the Choroid and Retina (GACR): A Cohort Study.

    Balfoort BM, Van den Broeck F, Boon CJF, et al.

    Journal of inherited metabolic disease 2025; (48(1)):e12842 doi:10.1002/jimd.12842.

    PMID: 39761806
  8. 8

    Extending diagnostic practices in gyrate atrophy: Enzymatic characterization and the development of an in vitro pyridoxine responsiveness assay.

    Balfoort BM, Pampalone G, Ruiter JPN, et al.

    Molecular genetics and metabolism 2024; (143(1-2)):108542 doi:10.1016/j.ymgme.2024.108542.

    PMID: 39053126
  9. 9

    Gyrate Atrophy of the Choroid and Retina Diagnosed in Adulthood With a Homozygous OAT Variant: A Case Report Highlighting the Need for Long-Term Care.

    Taniai H, Mizobuchi K, Hara T, et al.

    Case reports in ophthalmological medicine 2026; (2026()):8380205 doi:10.1155/crop/8380205.

    PMID: 42064147
  10. 10

    The coincidence of two ultra-rare hereditary eye diseases: gyrate atrophy and Kjer optic atrophy - a surprising diagnosis based on next-generation sequencing.

    Skorczyk-Werner A, Raczynska D, Wawrocka A, et al.

    Intractable & rare diseases research 2021; (10(3)):202-206 doi:10.5582/irdr.2021.01042.

    PMID: 34466343
  11. 11

    Obscured interdigitation zone at the early stage of gyrate atrophy: A case report.

    Nitta K, Mukai R, Akiyama H

    American journal of ophthalmology case reports 2022; (25()):101277 doi:10.1016/j.ajoc.2022.101277.

    PMID: 35112019
  12. 12

    Widefield Retinal Imaging in Gyrate Atrophy: Correlation of Structural, Biochemical, and Functional Characteristics.

    Padhy SK, Parameswarappa DC, Sharma S, et al.

    Ophthalmology. Retina 2025; (9(4)):392-401 doi:10.1016/j.oret.2024.10.016.

    PMID: 39447872
  13. 13

    Ultrawide field fluorescein angiogram in a family with gyrate atrophy and foveoschisis.

    Tripathy K, Chawla R, Sharma YR, Gogia V

    Oman journal of ophthalmology 2016; (9(2)):104-6 doi:10.4103/0974-620X.184529.

    PMID: 27433038
  14. 14

    A cohort study of 19 patients with gyrate atrophy of the choroid and retina (GACR).

    Balfoort BM, Van Den Broeck F, Brands MM, et al.

    Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie 2024; (262(11)):3589-3596 doi:10.1007/s00417-024-06540-8.

    PMID: 38847892
  15. 15

    Fundus autofluorescence imaging in hereditary retinal diseases.

    Pichi F, Abboud EB, Ghazi NG, Khan AO

    Acta ophthalmologica 2018; (96(5)):e549-e561 doi:10.1111/aos.13602.

    PMID: 29098804
  16. 16

    Clinical application of ultra-widefield fundus autofluorescence.

    Xu A, Chen C

    International ophthalmology 2021; (41(2)):727-741 doi:10.1007/s10792-020-01609-9.

    PMID: 33040254

This page is for informational purposes only and does not constitute medical advice. An ophthalmologist, metabolic specialist, or genetics professional should interpret your Gyrate Atrophy results and guide next steps.

Guide contents Gyrate atrophy of choroid and retina
Research & Literature
03 Biology and Look-Alike Conditions 05 Treatment and Metabolic Management