IMR Press / JIN / Volume 23 / Issue 1 / DOI: 10.31083/j.jin2301004
Open Access Opinion
Tissue Iron in Friedreich Ataxia
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1 Research Service (151), VA Medical Center, Albany, NY 12208, USA
*Correspondence: arnulf.koeppen@med.va.gov (Arnulf H Koeppen)
J. Integr. Neurosci. 2024, 23(1), 4; https://doi.org/10.31083/j.jin2301004
Submitted: 6 July 2023 | Revised: 19 August 2023 | Accepted: 23 August 2023 | Published: 10 January 2024
Copyright: © 2024 The Author(s). Published by IMR Press.
This is an open access article under the CC BY 4.0 license.
Abstract

Heart, dentate nucleus, and dorsal root ganglia (DRG) are targets of tissue damage in Friedreich ataxia (FA). This report summarizes the histology and histopathology of iron in the main tissues affected by FA. None of the affected anatomical sites reveals an elevation of total iron levels. In the myocardium, a small percentage of fibers shows iron-reactive granular inclusions. The accumulation of larger iron aggregates and fiber invasion cause necrosis and damage to the contractile apparatus. In the dentate nucleus, the principal FA-caused tissue injury is neuronal atrophy and grumose reaction. X-ray fluorescence mapping of iron in the dentate nucleus in FA shows retention of the metal in the center of the collapsed structure. Immunohistochemistry of ferritin, a surrogate marker of tissue iron, confirms strong expression in oligodendrocytes of the efferent white matter of the dentate nucleus and abundance of ferritin-positive microglia in the atrophic gray matter. Iron dysmetabolism in DRG is complex and consists of prominent expression of ferritin in hyperplastic satellite cells and residual nodules, also a loss of the iron export protein ferroportin from the cytoplasm of the remaining DRG nerve cells.

Keywords
friedreich ataxia
ferritin
iron
mitochondrial ferritin
ferroportin
cardiomyopathy
atrophy
dorsal root ganglia
Funding
R01-NS069454/National Institutes of Health
Friedreich’s Ataxia Research Alliance
Figures
Fig. 1.
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