A 17 year old man with a 9 month history of progressive speech and swallowing difficulties as well as weight loss was admitted to hospital with pneumonia. He and his family noticed twitches of his upper limbs. No weakness or sensory symptoms in the limbs. His hearing and vision were normal. His grandfather had problems with swallowing and dropping things in his seventies. On examination he had myopathic facies with myoclonic jerks in the upper limbs.The tongue was wasted, fasciculating and weak. The neck muscles were strong and eye movements full. The limbs examination revealed no wasting with fasciculations in paraspinal muscles, normal power and symmetrical reflexes. There were no sensory, cerebellar or extrapyramidal features. Routine bloods were normal and an MRI of the neuroaxis as well as CT chest abdomen and pelvis were unremarkable. NCS/EMG was consistent with anterior horn cell disorder and EEG showed multiple paroxysmal generalised spike and wave. Genetic testing including Kennedy’s, Brown-Vialetto-Van Laere Syndrome were negative although pathogenic mutations FUS (Fused in Sarcoma) confirmed FUS MND. FUS MND is a rare cause of familial MND accounting for 4% of all cases with mutant FUS altering global RNA splicing.