<prompt> All of the following are genetic motor neuron diseases affecting predominantly lower motor neurons exceptSpinal muscular atrophySandhoffs diseaseAdult tay sachs diseaseAdrenoleukodystrophy  <response>: Spinal muscular atrophy, Sandhoffs disease, Adult tay sachs disease are genetic motor neuron disease affecting lower motor neurons. Adrenoleukodystrophy is a genetic motor neuron disease affecting upper motor neurons. Ref Harrison 20th edition page 3144 , table 429-3 