Facial Onset Motor and Sensory Neuronopathy Syndrome With a Novel TARDBP Mutation

Facial onset sensory and motor neuronopathy (FOSMN) syndrome was a rare and slowly progressive neurodegenerative disorder, which heralded by sensory symptoms within the face, and followed by evolution of sensory and motor deficits in the face and limbs. The underlying pathogenesis of FOSMN remains to be fully elucidated.

A 40-year-old man was admitted to our hospital with facial sensory deficits spreading in a rostral-caudal manner. He then developed diffuse fasciculation, bulbar signs, atrophy and weakness of facial, neck, and limb muscles progressively, a process resembling amyotrophic lateral sclerosis. Neurophysiological studies demonstrated abnormal blink reflexes and some denervation-reinnervation changes in electromyogram. He was diagnosed with FOSMN syndrome clinically. A novel heterozygous Gly386Glu mutation in the transactive response DNA-binding protein (TARDBP) gene was found. The patient had no response to immunologic treatment and finally died of respiratory failure.

This is the first time that a novel mutation in TARDBP gene was identified in a patient with FOSMN syndrome, which further suggested a link between FOSMN and amyotrophic lateral sclerosis. Our findings widen the spectrum of TARDBP-related motor neuron diseases.