title: A rat model of Charcot-Marie-Tooth disease 1A recapitulates disease variability and supplies biomarkers of axonal loss in patients.
abstract: Charcot-Marie-Tooth disease is the most common inherited neuropathy and a duplication of the peripheral myelin protein 22 gene causes the most frequent subform Charcot-Marie-Tooth 1A. Patients develop a slowly progressive dysmyelinating and demyelinating peripheral neuropathy and distally pronounced muscle atrophy. The amount of axonal loss determines disease severity. Although patients share an identical monogenetic defect, the disease progression is strikingly variable and the impending disease course can not be predicted in individual patients. Despite promising experimental data, recent therapy trials have failed. Established clinical outcome measures are thought to be too insensitive to detect amelioration within trials. Surrogate biomarkers of disease severity in Charcot-Marie-Tooth 1A are thus urgently needed. Peripheral myelin protein 22 transgenic rats harbouring additional copies of the peripheral myelin protein 22 gene ('Charcot-Marie-Tooth rats'), which were kept on an outbred background mimic disease hallmarks and phenocopy the variable disease severity of patients with Charcot-Marie-Tooth 1A. Hence, we used the Charcot-Marie-Tooth rat to dissect prospective and surrogate markers of disease severity derived from sciatic nerve and skin tissue messenger RNA extracts. Gene set enrichment analysis of sciatic nerve transcriptomes revealed that dysregulation of lipid metabolism associated genes such as peroxisome proliferator-activated receptor gamma constitutes a modifier of present and future disease severity. Importantly, we directly validated disease severity markers from the Charcot-Marie-Tooth rats in 46 patients with Charcot-Marie-Tooth 1A. Our data suggest that the combination of age and cutaneous messenger RNA levels of glutathione S-transferase theta 2 and cathepsin A composes a strong indicator of disease severity in patients with Charcot-Marie-Tooth 1A, as quantified by the Charcot-Marie-Tooth Neuropathy Score. This translational approach, utilizing a transgenic animal model, demonstrates that transcriptional analysis of skin biopsy is suitable to identify biomarkers of Charcot-Marie-Tooth 1A.
authors.affiliation: Department of Neurogenetics, Max-Planck-Institute of Experimental Medicine, Hermann-Rein-Str. 3, D-37075 Göttingen, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Fledrich
authors.forename: Beate
authors.initials: B
authors.lastname: Schlotter-Weigel
authors.forename: Tuuli J
authors.initials: TJ
authors.lastname: Schnizer
authors.forename: Sven P
authors.initials: SP
authors.lastname: Wichert
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Stassart
authors.forename: Gerd
authors.initials: G
authors.lastname: Meyer zu Hörste
authors.forename: Axel
authors.initials: A
authors.lastname: Klink
authors.forename: Bernhard G
authors.initials: BG
authors.lastname: Weiss
authors.forename: Uwe
authors.initials: U
authors.lastname: Haag
authors.forename: Maggie C
authors.initials: MC
authors.lastname: Walter
authors.forename: Bernd
authors.initials: B
authors.lastname: Rautenstrauss
authors.forename: Walter
authors.initials: W
authors.lastname: Paulus
authors.forename: Moritz J
authors.initials: MJ
authors.lastname: Rossner
authors.forename: Michael W
authors.initials: MW
authors.lastname: Sereda
mesh_terms: D000818:Animals; D001369:Axons / Q000473:pathology* / Q000502:physiology; D002607:Charcot-Marie-Tooth Disease / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology; D004195:Disease Models, Animal; D005982:Glutathione Transferase / Q000235:genetics; D018993:Myelin P0 Protein / Q000235:genetics; D009185:Myelin Proteins / Q000235:genetics*; D009431:Neural Conduction / Q000502:physiology; D047495:PPAR gamma / Q000235:genetics; D010147:Pain Measurement; D010641:Phenotype; D051381:Rats; D055647:Rats, Transgenic; D012584:Sciatic Nerve / Q000473:pathology* / Q000503:physiopathology; D012720:Severity of Illness Index
chemical_list: D018993:Myelin P0 Protein; D009185:Myelin Proteins; D047495:PPAR gamma; C489546:Pmp22 protein, rat; D005982:Glutathione Transferase