Novel genetic and nerve imaging characterization of Charcot-Marie-Tooth disease type 4F.

Charcot-Marie-Tooth disease type 4F (CMT4F) is a rare hereditary sensorimotor neuropathy, linked to the periaxin (PRX) gene. Early onset, pronounced sensory ataxia and comparatively moderate muscular weakness are characteristic hallmarks. We here report a child with corresponding features carrying a pathogenic PRX variant in trans with a very rare variant of uncertain significance in the 5’ untranslated region predicted to interfere with splicing. High-resolution ultrasound depicted an age-related pattern of nerve enlargement and muscle hyperechogenicity resembling other CMT4 subtypes with similar clinical and histopathological characteristics. Based on this differential analysis, we propose these genetic findings to be possibly causative.