Oculopharyngeal Muscular Dystrophy (OPMD)

Oculopharyngeal Muscular Dystrophy (OPMD)

What is oculopharyngeal muscular dystrophy (OPMD)?

OPMD is a rare, slowly progressive myopathy that is characterized by weakness of the eyelids (ocular) and throat (pharyngeal) muscles. Additionally, OPMD can be associated with proximal (near the body midline) and distal (limb) muscle weakness.

What are the symptoms of OPMD?

Difficulty swallowing (dysphagia) and droopy eyelids (ptosis) are the most common manifestations of the disease. When the disease progresses, some people with OPMD also experience mobility difficulties. For more, see Signs and Symptoms.

What causes OPMD?

OPMD is caused by a genetic defect in the PABPN1 gene, which leads to the production of a nonfunctional protein that forms clumps in the muscle cells.¹ OPMD affects men and women equally, and this genetic defect can be inherited from either one parent (autosomal dominant, the most common form) or both parents (autosomal recessive form).¹

The prevalence of the autosomal dominant form is estimated to be 1 in 100,000 in Western countries. Because of the “founder effect,” which happens when a founder of a new population has a genetic mutation, the prevalence of OPMD is higher in French Canadians and Bukhara Jews living in Israel.^1,2

For more, see Causes/Inheritance.

What is the onset and progression of OPMD?

Symptoms of OPMD usually do not appear until the 40s or 50s, and weakness progresses slowly. The mean age of onset of ptosis is 48 years, and the mean age of onset of dysphagia is 50 years.¹

What is the status of research in OPMD?

Researchers have identified the genetic cause for OPMD, and MDA-supported scientists are building on that knowledge in a variety of ways. For more, see Research.

References

1. Trollet C, Gidaro T, Klein P, et al. Oculopharyngeal Muscular Dystrophy. 2001 Mar 8 [Updated 2014 Feb 20]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2020
2. Raz V, Butler-Browne G, van Engelen B, Brais B. 191st ENMC International Workshop: Recent advances in oculopharyngeal muscular dystrophy research: From bench to bedside 8-10 June 2012, Naarden, The Netherlands. Neuromuscul Disord. 2013;23(6):516-523. doi:10.1016/j.nmd.2013.03.001