Adult-onset demyelinating neuropathy associated with FBLN5 gene mutation

Abstract

Rare forms of autosomal-dominant Charcot-Marie-Tooth disease (AD-CMT) may be associated with mutations in Fibulin-5 (FBLN5) as AD-CMT is genetically heterogeneous. Here, we report the first pathological study of an Asian family. The proband was a 46-year-old man with slowly progressive distal numbness and weakness for 12 years. He had a history of diabetes mellitus for 12 years. His mother was 81 years old and had mild polyneuropathy. His 16-year-old daughter was asymptomatic. The nerve conduction velocities (NCVs) and compound muscular action potential (CMAP) amplitudes were moderately to severely reduced in the proband, and moderately reduced in his daughter and mother. A sensory response could not be elicited in the proband and was moderately to severely decreased in the daughter and mother. Nerve ultrasound indicated a general enlargement of the peripheral nerves in the proband, daughter, and mother. A sural nerve biopsy from the proband demonstrated a pronounced depletion of myelinated fibers, thin myelinated fibers, and onion-bulb formations. A reported heterozygous mutation of c.1117C > T in FBLN5 was identified in the proband, mother, and daughter. These findings confirm a novel subtype of AD-CMT 1 due to a mutation in the FBLN5 gene.