FLD produces rapidly progressive weakness of tongue, face and pharyngeal muscles in a clinical pattern similar to myasthenia.

It causes progressive bulbar paralysis due to involvement of motor neurons of the cranial nerve nuclei.

[4][5][additional citation(s) needed] Fazio–Londe disease is linked to a genetic mutation in the SLC52A3 gene on chromosome 20 (locus: 20p13).

[7] Symptoms of Fazio–Londe include bulbar palsy, hearing loss, facial weakness, and difficulty breathing.

[citation needed] 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.

The histologic alterations found in patient with Fazio–Londe disease were identical to those seen in infantile-onset spinal muscular atrophy.

The child was ambulant and apparently normal until 3 months back when he developed respiratory distress and was treated at a local hospital prior to referral.

[11] It is named for the Italian pathologist Eugenio Fazio (1849–1902) and the French physician Paul Frederic Louis Londe (1864–1944).