Spinal muscular atrophy with progressive myoclonic epilepsy

Spinal muscular atrophy with progressive myoclonic epilepsy
Synonyms	Hereditary myoclonus-progressive distal muscular atrophy syndrome
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Field	neurology
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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.<ref>,

 Spinal Muscular Atrophy with Progressive Myoclonic Epilepsy: Report of New Cases and Review of the Literature, 
 Neuropediatrics, 
 2002,
 Vol. 33(Issue: 6),
 pp. 314–319,
 DOI: 10.1055/s-2002-37087,
 PMID: 12571787,</ref> Only 12 known families are described in scientific literature to have SMA-PME.<ref name=":0">

Reference, Genetics Home. Spinal muscular atrophy with progressive myoclonic epilepsy(link). Genetics Home Reference.

Accessed 2018-09-24.

</ref>

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.<ref>,

 Spinal Muscular Atrophy Associated with Progressive Myoclonic Epilepsy is Caused by Mutations in ASAH1, 
 The American Journal of Human Genetics, 
 2012,
 Vol. 91(Issue: 1),
 pp. 5–14,
 DOI: 10.1016/j.ajhg.2012.05.001,
 PMID: 22703880,
 PMC: 3397266,</ref> SMA-PME is closely related to a lysosomal disorder disease called Farber lipogranulomatosis.<ref>, 
 Acid ceramidase deficiency associated with spinal muscular atrophy with progressive myoclonic epilepsy, 
 Neuromuscular Disorders, 
 
 Vol. 25(Issue: 12),
 pp. 959–963,
 DOI: 10.1016/j.nmd.2015.09.007,
 PMID: 26526000,</ref> 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.<ref>,

 Hereditary myoclonus and progressive distal muscular atrophy, 
 Annals of Neurology, 
 1979,
 Vol. 6(Issue: 3),
 pp. 227–231,
 DOI: 10.1002/ana.410060309,
 PMID: 534421,</ref>

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 <ref>Park, Jae-Ho,

 Acid ceramidase and human disease, 
 Biochimica et Biophysica Acta, 
 
 Vol. 1758(Issue: 12),
 pp. 2133–2138,
 DOI: 10.1016/j.bbamem.2006.08.019,
 PMID: 17064658,</ref> 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.<ref>Morell, Pierre, 
 The Myelin Sheath, 
 Basic Neurochemistry: Molecular, Cellular and Medical Aspects. 6th Edition, 
 
 
 
 
 
 
 
 Full text,</ref> In patients with SMA-PME, the cermidase function is reduced to only be 33.33% effective.<ref name=":0" /> 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. Genetics Home Reference: Spinal muscular atrophy with progressive myoclonic epilepsy(link). {{{website}}}.

December 2013.

External links

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