Oculopharyngeal Muscular Dystrophy (OPMD)

 

OPMD can cause difficulty swallowing and weakness in the muscles and body.

What causes OPMD?

This condition is caused by a variant in the PABN1 gene (see figure 1). This gene encodes for a protein that is important for mRNA processing and regulation, otherwise known as protein creation (2).

The genetic change that causes OPMD creates a small expansion of a portion of protein, which impairs its proper function. When this occurs, the PABN1 proteins clump together around muscle cells, jeopardizing typical muscle function, which is how the muscles become weakened (2).

What is OPMD?

Oculophayngeal Muscular Dystrophy (OPMD) is a rare genetic disorder that affects adults between the ages of 40 and 50 years old. It is classified as a neuromuscular disorder. Common symptoms include facial muscle weakness and as a result, impaired vision, difficulty swallowing, speech difficulties, and heavy or droopy eyelids (typically both eyelids rather than just one). Additionally, individuals may experience both upper and lower body weakness (1, 3).

Figure 1. The additional genetic material gained in those with OPMD is referred to as a triplet expansion and is the cause of the symptoms of OPMD.

This image is shared with permission from the following source:

Trollet C, Boulinguiez A, Roth F, et al. Oculopharyngeal Muscular Dystrophy. 2001 Mar 8 [Updated 2020 Oct 22]. In: Adam MP, Feldman J, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1126/

 
 

What Treatments are available?

The treatment for OMPD has to do with medical management, rather than a cure for the disease. However, there is current research in looking for an effective treatment. BB-301 is a gene therapy treatment that targets and silences the nonfunctional PABN1 protein and replaces it with a functioning version. The goal of the treatment is to reduce the condition-related symptoms and provide longer lasting management for those with OPMD. The current clinical study of BB-301 has a few patients involved, where scientists and physicians are evaluating the safety of the treatment for the patients who are receiving treatment as part of the study. Updates regarding the efficacy of the benefits should be available during 2025 along with efforts to advance the trial (4).

 
 

How can genetic counseling help
Those with or suspected of having OPMD?

This condition is inherited in an autosomal dominant pattern, meaning that one genetic variant is enough to cause the disorder. Therefore, if there are family members who have similar symptoms or diagnoses of OPMD, it is important to meet with a genetic counselor to discuss genetic testing, condition management, and other familial risk factors. Clover Genetics is a telehealth genetic counseling practice that can help patients and families experiencing symptoms or diagnosed with OPMD. Clover Genetics can facilitate genetic testing for OPMD through a saliva test via a noninvasive testing kit sent to your house, with results returned within a few weeks. Genetic counselors at Clover Genetics can also provide services like psychosocial support for patients, family planning tools, and cascade genetic testing for other family members of an individual diagnosed with OPMD at the time of the appointment.

We are listed in the OPMD Association registry for genetic counselors on their website.
Visit their website to learn more about how the OPMD Association can assist patients.