Oculopharyngeal Muscular Dystrophy

An autosomal dominant muscular disorder in which the gene defect consists of short GCG expansions in the PABP2 (poly-A binding protein 2) gene on chromosome 14.

Onset usually occurs in patients in their 50s and 60s. Patients develop ptosis that is almost always bilateral. Typically, contraction of the occipitofrontal muscle is prominent, and the patient tips the head back to compensate visually for the ptosis. Dysphagia for solid foods usually follows extraocular weakness. Palatal mobility is often diminished, and the gag reflex is impaired. Laryngeal weakness with dysphonia is common.

Oculopharyngeal muscular dystrophy resembles myasthenia gravis. However, unlike with myasthenia gravis, tendon reflexes may be diminished or even absent with this disorder. Some patients report cramps in calf muscles despite the absence of significant weakness. Years after onset, the muscles of the limbs, especially of the proximal hip girdle, may become weak.

The diagnosis depends on clinical features and a positive family history. DNA analysis is being developed.

Limb weakness occasionally occurs, but long-term disability results from dysphagia and aspiration pneumonitis. With improvements in care (eg, improved swallowing, supplemental nutrition), patients usually have a normal life span and relatively normal abilities to perform activities of daily living.

No specific treatment is available. However, the use of cricopharyngeal myotomy for dysphagia is helpful.