Selected missense mutations impair frataxin processing in Friedreich ataxia

Elisia Clark, Jill S. Butler, Charles J. Isaacs, Marek Napierela and David R. Lynch; Annals of Clinical and Translational Neurology. doi: 10.1002/acn3.433

FXNI154F and FXNG130V missense mutations decrease FXN81–210 levels compared with FXNWT, FXNR165C, and FXNW155R, but do not block its association with mitochondria. FXNI154F and FXNG130V also impair FXN maturation and enhance the binding between FXN42–210 and mitochondria processing peptidase. Furthermore, blocking proteosomal degradation does not increase FXN81–210 levels. Additionally, impaired FXN processing also occurs in fibroblasts from patients with FXNG130V. Finally, clinical data from patients with FXNG130V and FXNI154F mutations demonstrates a lower severity compared with other individuals with Friedreich ataxia.