Oculopharyngeal muscular dystrophy

Oculopharyngeal muscular dystrophy
Classification and external resources
ICD-10	G71.0
ICD-9	359.1
OMIM	164300
DiseasesDB	29869
MeSH	D039141

Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant^[1] neuromuscular disease which appears in early middle age (sixth decade).^[2] OPMD is an example of a trinucleotide repeat disorder caused by expanding (GCN)₁₀ to (GCN)_11-17 at the 5' end of the coding region for PABPN1. This expands the polyalanine tract at the N-terminus of PABPN1 from 10 to 11-17 alanines.^[3][4]

Signs and symptoms

Progressive ptosis (drooping of eyelids)and weakness of the extraocular muscles is the initial clinical finding which continues until paralysis of all eye movements occurs; however, pupillary reactions remain unaffected. Dysphagia (difficulty swallowing), facial weakness and proximal limb weakness develops later on in the disease. ^[2]

Diagnosis

A muscle biopsy reveals abnormal vacuoles within muscle fibres. A distinction between OPMD and myasthenia gravis or mitochondrial myopathy must be made. The absence of family history and the fluctuation of symptoms in myasthenia gravis usually distinguish the two conditions.^[5]

Epidemiology

The disease is frequently seen in French Canadians, with a prevalence 1:1000. A 1997 study from Israel showed the second largest cluster of known individuals are of Bukhara Jews from Uzbekistan, with a calculated minimal prevalence of 1:600. ^[6] The disease is uncommon in Asian populations. ^[7]

Treatment

Treatment is supportive to the patient with death eventually occurring from infections. Difficulty with swallowing may result in nasogastric feeding.^[3] Some surgeries are available that can reduce ptosis and dysphagia.^[8]

References

1. ^ Davies Je, B. Z. (February 2006). "Oculopharyngeal muscular dystrophy: Potential therapies for an aggregate-associated disorder". The International Journal of Biochemistry & Cell Biology 38 (9): 1457–1462. doi:10.1016/j.biocel.2006.01.016. PMID 16530457.  edit
2. ^ ^{a b} Brais B, Bouchard JP, Xie YG, et al. (Feb 1998). "Short GCG expansions in the PABP2 gene cause oculopharyngeal muscular dystrophy". Nat. Genet. 18 (2): 164–7. doi:10.1038/ng0298-164. PMID 9462747. 
3. ^ ^{a b} Lindsay, Kenneth W; Ian Bone, Robin Callander, J. van Gijn (1991). Neurology and Neurosurgery Illustrated. United States: Churchill Livingstone. pp. 453. ISBN 0-443-04345-0. 
4. ^ Goh KJ, Wong KT, Nishino I, Minami N, Nonaka I (2005). "Oculopharyngeal muscular dystrophy with PABPN1 mutation in a Chinese Malaysian woman". Neuromuscul. Disord. 15 (3): 262–4. doi:10.1016/j.nmd.2004.10.016. PMID 15725589. http://linkinghub.elsevier.com/retrieve/pii/S0960-8966(04)00308-6. 
5. ^ http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=opmd
6. ^ http://www.ncbi.nlm.nih.gov/pubmed/9392014
7. ^ http://memo.cgu.edu.tw/cgmj/3301/330105.pdf
8. ^ Brais, B (2009 Jan). "Oculopharyngeal muscular dystrophy: a polyalanine myopathy.". Current neurology and neuroscience reports 9 (1): 76–82. PMID 19080757. 

External links

• opmd at NIH/UW GeneTests
• Muscular Dystrophy Association's website in Greece
• Oculopharyngeal muscular dystrophy at NIH's Office of Rare Diseases

GeneReviews Washington State University, funded by NIH