[1] Beaumont Hosp, Dept Neurol, Dublin 9, Ireland
[2] Our Ladys Hosp Sick Children, Natl Ctr Med Genet, Dublin, Ireland
[3] St James Hosp, Dublin, Ireland
[4] Motor Neuron Dis Asoc Ireland, Dublin, Ireland
[5] Beaumont Hosp, Dept Neuropathol, Dublin, Ireland
[6] Univ Coll Dublin, Conway Inst, Dept Med Genet, Dublin 2, Ireland