A 3-month-old infant presents to your clinic with difficulty moving his extremities. The child had an uneventful prenatal course and birth, but since birth he has had poor head control and difficulty feeding. On physical exam, he is able to move all extremities, but he moves his upper extremities more than his lower extremities, and his hands more than his shoulders. He has no spasticity, but global weakness. The patient’s deep tendon reflexes are absent, but he has tongue fasciculations. What is the cellular pathology and prognosis for this patient?