Acknowledgement of Oculopharyngeal Muscular Dystrophy has not been added yet.

OPMD has been reported in people from more than 30 countries worldwide and is estimated to occur in approximately 1 in 100,000 people in Europe. This condition occurs more frequently in some populations, including in French-Canadians in Quebec, where the prevalence is estimated at 1 in 1,000, and among Bukhara Jews living in Israel in approximately 1 in 600 individuals.

Name	Abbreviation
Progressive muscular dystrophy, oculopharyngeal type

OPMD is a genetic disorder caused by a change (variant or mutation) in a person’s genetic code that results in an abnormal impact to the body. Specifically, a change in the PABPN1 gene causes OPMD. The PABPN1 gene gives the instructions for the cells in the body to make the PABPN1 protein. This protein is important for processing, protecting, and moving other molecules called messenger RNAs (mRNAs), which are molecules that serve as a template for making other proteins. One part of the normal PABPN1 protein includes a portion where ten molecules of alanine, one of the protein building blocks or amino acids, occur in a row in what is called a polyalanine tract. In individuals with OPMD, this polyalanine tract is expanded and includes 11 to 18 alanines instead of ten, with 13 alanines being most common in affected individuals. These additional alanine molecules cause the PABPN1 protein to form clumps, called intranuclear inclusions, that accumulate in the muscle cells, which causes the muscle cells to malfunction and die. The muscle weakness experienced by individuals with OPMD is caused by the loss of muscle cells over time; the intranuclear inclusions might also impact nerve cells. OPMD usually follows an autosomal dominant inheritance pattern, meaning that one copy of the PABPN1 gene with the expanded polyalanine tract is enough to cause the condition, and individuals affected with this condition often have a parent who is also affected. In some individuals with more severe or earlier-onset disease, both copies of the PABPN1 gene include the expanded polyalanine tract. The age at symptom onset and the severity of the muscle weakness are also related to the number of alanines in the tracts, with fewer alanines often found in conjunction with later onset and/or less severe disease and more alanines found in individuals with earlier onset and/or more severe disease.

 

The most common symptoms of OPMD include droopy eyelids (ptosis), swallowing difficulties (dysphagia), weakness of the tongue, weakness in the upper part of the legs (proximal lower-extremity weakness), fatigue, and a wet-sounding voice. Less common features include limited ability to look upward, facial muscle weakness, speaking difficulties due to weakness in the muscles used for speaking (dysarthria), hoarseness or otherwise altered voice (dysphonia), and weakness in the upper part of the arms (proximal upper-extremity weakness). The least common symptoms include difficulties remembering, concentrating, making decisions, and learning new things (cognitive impairment), neck muscle weakness, weakness in the lower parts of the arms and legs (distal limb weakness), repeated starting and stopping breathing while sleeping (sleep apnea), irregular heartbeat (cardiac arrhythmia), and damage to the nerves that send signals between the brain and spinal cord and other parts of the body (peripheral neuropathy).

OPMD is diagnosed in an individual who shows signs and symptoms consistent with the disorder and who is shown by molecular genetic testing to have one or two copies of the expanded polyalanine tract.

Diagnostic Tests

Molecular genetic testing: When a person shows signs and symptoms that may indicate a diagnosis of OPMD or another disorder that has similar features, an appropriate approach may be targeted gene testing, where only the PABPN1 gene or a small group of genes that includes PABPN1 gene and other genes that might be of interest are tested. In an individual whose signs and symptoms may be atypical, comprehensive genomic testing, such as exome or genome sequencing, where all the genes are tested, could be a better option. 

Muscle biopsy: In some individuals, a muscle biopsy also may be performed in order to examine the muscle tissue for the presence of the intranuclear inclusions and to determine whether there are other changes to the muscle fibers. Muscle biopsy typically is performed only when an individual has features that could suggest OPMD but has two unexpanded copies of PABPN1 and non-diagnostic genetic test results for genes associated with other similar disorders.  

Diagnostic tests of Oculopharyngeal Muscular Dystrophy has not been added yet

Ptosis: Surgery to correct the ptosis is recommended when vision interference occurs or when neck pain occurs from tilting the head back to compensate for the vision interference. 

Dysphagia: Food should be cut into small, easy to swallow, pieces. Surgery can be considered when swallowing difficulties impact quality of life. 

Limb muscle weakness: Occupational and/or physical therapy are encouraged. Affected individuals may need to use canes or walkers to avoid falls and those with severe disease may require a wheelchair.

Cognitive impairment: Evaluation by a neurologist and/or psychologist may be recommended.

Other: To reduce the risk of complications associated with OPMD, such as aspiration pneumonia and weight loss, affected individuals may consider keeping up-to-date with annual influenza vaccinations or using dietary supplements for those with significant weight loss.

 

OPMD does not appear to impact life expectancy, though affected individuals may experience diminished quality of life, particularly in later years.

Tips or Suggestions of Oculopharyngeal Muscular Dystrophy has not been added yet.

• https://medlineplus.gov/genetics/condition/oculopharyngeal-muscular-dystrophy/

• https://www.ncbi.nlm.nih.gov/books/NBK1126/

• https://www.omim.org/entry/164300