Longitudinal case study and phenotypic multimodal characterization of McArdle disease-linked retinopathy: insight into pathomechanisms

Ophthalmic Genet. 2020 Feb;41(1):73-78. doi: 10.1080/13816810.2020.1727536. Epub 2020 Mar 3.


Background: We present a longitudinal clinical characterization of PYGM-linked pattern dystrophy in an adult male patient.Materials and Methods: A patient affected by McArdle disease (glycogen storage disease type V) and homozygous for the nonsense variant PYGM c.148C>T p.(Arg50*) underwent ophthalmic examinations over a 9-year-interval, including fundus photography, fundus autofluorescence, optical coherence tomography (OCT), OCT-angiography and electroretinography (ERG).Results: At age 52, the patient was asymptomatic but yellow flecks were first observed in the macula of both eyes. This yellow flecks at the posterior pole progressed towards a pattern-like dystrophy over a 5-year-period. By fundus autofluorescence imaging the appearance of new hyperautofluorescent flecks and the extension of existing ones was observed over time. Concomitantly, a slow progression of the size of atrophic areas was seen at the posterior pole. Scotopic ERGs were within normal limits, but photopic Flicker responses were decreased, indicating reduced cone function.Conclusions: This additional case of PYGM-linked pattern dystrophy further confirms retinopathy as a clinical phenotype associated with McArdle disease. PYGM expression pattern suggests a disease mechanism involving impaired glycogen metabolism both in the retinal pigment epithelium and in cone photoreceptors.

Keywords: PYGM; Retinopathy; glycogen phosphorylase; glycogen storage disease; pattern dystrophy.

Publication types

  • Case Reports

MeSH terms

  • Electroretinography / methods*
  • Fluorescein Angiography / methods*
  • Glycogen Storage Disease Type V / complications
  • Glycogen Storage Disease Type V / diagnostic imaging
  • Glycogen Storage Disease Type V / pathology*
  • Humans
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Phenotype
  • Retinal Cone Photoreceptor Cells
  • Retinal Diseases / complications
  • Retinal Diseases / diagnostic imaging
  • Retinal Diseases / pathology*
  • Tomography, Optical Coherence / methods*
  • Visual Acuity