Frataxin and ATP5B immunohistochemistry of a normal control DRG and a DRG of an FA patient. (a)-(c) normal control; (d)-(f) FA; (a) and (d) frataxin; (b) and (e) anti-frataxin antibody pre-absorbed by human recombinant frataxin; (c) and (f) ATP5B. In the normal DRG, granular frataxin reaction product fills the perikarya of all neurons (a). Reaction product in satellite cells is sparse. ATP5B immunohistochemistry yields a similar result (c). In FA (d-f), frataxin reaction product in small neurons is concentrated under the neuronal plasma membrane, and hyperplastic satellite cells display more frataxin-reactive granules than normal (d). In FA, ATP5B reaction product shows a distribution in neurons, hyperplastic satellite cells, and a residual nodule that resembles frataxin (f, arrow). Two neurons are outlined by interrupted lines. Bars, 20 μm.