Spinal muscular atrophy with progressive myoclonic epilepsy

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 wasting (atrophy), predominantly affecting distal muscles, combined with denervation and myoclonic seizures. Only 12 known families are described in scientific literature to have SMA-PME.

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. SMA-PME is closely related to a lysosomal disorder disease called Farber lipogranulomatosis. As with many genetic disorders, there is no known cure to SMA-PME.

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

ASAH1 Gene

The ASAH1 Gene codes for acid ceramidase which is an enzyme found in lysosomes. The lysosome breaks down acid ceramidase and the fatty acid component is then used to produce myelin. Myelin is a coating around the nerves in the body which help transfer signals from nerve cell to nerve cell and increase transmission rate. In patients with SMA-PME, the cermidase function is reduced to only be 33.33% effective. The lack of myelin resulting from the lack of acid ceramidase break down leads to nerve cell damage.

See also

• Spinal muscular atrophies
• Progressive myoclonus epilepsy

Further reading

• National Institutes of Health (December 2013). "Genetics Home Reference: Spinal muscular atrophy with progressive myoclonic epilepsy".

External links

Classification	ICD-10: G25.3 OMIM: 159950
External resources	Orphanet: 2590