Onset of first symptom has been reported between 1–12 years, with a mean age of onset at 8 years. Clinical course can be divided into early (< 6 yrs age, predominance of respiratory symptoms) and late course (6–20 years of age, predominance of motor symptoms on superior limbs). Progression to involve other cranial nerve muscles occurs over a period of months or years. In the Gomez review facial nerve was affected in all cases while hypoglossal nerve was involved in all except one case. Other cranial nerves involved were vagus, trigeminal, spinal accessory nerve, abducent, occulomotor and glossopharyngeal in this order. Corticospinal tract signs were found in 2 of the 14 patients. The disease may progress to patient's death in a period as short as 9 months or may have a slow evolution or may show plateaus. Post mortem examination of cases have found depletion of nerve cells in the nuclei of cranial nerves. The histologic alterations found in patient with<unk>  were identical to those seen in infantile-onset spinal muscular atrophy. Strength may improve with administration of cholinesterase inhibitors.
Fazio–Londe disease
XMEN disease
Hajdu–Cheney syndrome
Crigler–Najjar syndrome
Baggio–Yoshinari syndrome
Klüver–Bucy syndrome
DeSanto-Shinawi syndrome
Treacher Collins syndrome