The retinal phenotype in primary hyperoxaluria type 2 and 3

Johannes Birtel, Roselie M. Diederen, Philipp Herrmann, Sophie Kaspar, Bodo B. Beck, Sander F. Garrelfs, Bernd Hoppe, Peter Charbel Issa

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Abstract

Background: The primary hyperoxalurias (PH1-3) are rare inherited disorders of the glyoxylate metabolism characterized by endogenous overproduction of oxalate. As oxalate cannot be metabolized by humans, oxalate deposits may affect various organs, primarily the kidneys, bones, heart, and eyes. Vision loss induced by severe retinal deposits is commonly seen in infantile PH1; less frequently and milder retinal alterations are found in non-infantile PH1. Retinal disease has not systematically been investigated in patients with PH2 and PH3. Methods: A comprehensive ophthalmic examination was performed in 19 genetically confirmed PH2 (n = 7) and PH3 (n = 12) patients (median age 11 years, range 3–59). Results: Median best corrected visual acuity was 20/20. In 18 patients, no retinal oxalate deposits were found. A 30-year-old male with PH2 on maintenance hemodialysis with plasma oxalate (Pox) elevation (> 100 µmol/l; normal < 7.4) demonstrated bilateral drusen-like, hyperreflective deposits which were interpreted as crystallized oxalate. Two siblings of consanguineous parents with PH2 presented with retinal degeneration and vision loss; exome-wide analysis identified a second monogenic disease, NR2E3-associated retinal dystrophy. Conclusions: Retinal disease manifestation in PH2 and PH3 is rare but mild changes can occur at least in PH2-associated kidney failure. Decline in kidney function associated with elevated plasma oxalate levels could increase the risk of systemic oxalosis. Deep phenotyping combined with genomic profiling is vital to differentiate extrarenal disease in multisystem disorders such as PH from independent inherited (retinal) disease. Graphical abstract: [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)1485-1490
Number of pages6
JournalPediatric nephrology (Berlin, Germany)
Volume38
Issue number5
Early online date19 Oct 2022
DOIs
Publication statusPublished - May 2023

Keywords

  • Kidney failure
  • Optical coherence tomography
  • Phenotyping
  • Plasma oxalate
  • Primary hyperoxaluria
  • Retina

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