Spinal muscular atrophy with progressive myoclonic epilepsy
Other names	Hereditary myoclonus-progressive distal muscular atrophy syndrome
This condition is inherited in an autosomal recessive manner
Specialty	Neurology

Spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME), sometimes called Jankovic–Rivera syndrome, is a very rare neurodegenerative disease whose symptoms include slowly progressive muscle (atrophy), predominantly affecting proximal muscles, combined with denervation and myoclonic seizures.^[1] Only 12 known human families are described in scientific literature to have SMA-PME.^[2]

SMA-PME is associated with a missense mutation (c.125C→T) or deletion in exon 2 of the ASAH1 gene and is inherited in an autosomal recessive manner.^[3] SMA-PME is closely related to a lysosomal disorder disease called Farber lipogranulomatosis.^[4] As with many genetic disorders, there is no known cure for SMA-PME.

The condition was first described in 1979 by American researchers Joseph Jankovic and Victor M. Rivera.^[5]

ASAH1 gene

The ASAH1 gene codes for acid ceramidase, an enzyme found in lysosomes. The lysosome breaks down acid ceramidase; the fatty acid component ^[6] is then used to produce myelin. Myelin is an insulating coating around the neurons in the body which helps to contain bioelectrical signals along a nerve cell's axon and increase transmission rate.^[7] In patients with SMA-PME, the ceramidase function decreases to 33.33% effective.^[2] The lack of myelin resulting from the lack of acid ceramidase breakdown leads to nerve cell dysfunction.^{[citation needed]}