Myotonic dystrophy type 2 is a genetically inherited form of muscular dystrophy, which the National Human Genome Research Institute states begins between the ages 20 and 30. The National Institutes of Health (NIH) states that myotonic dystrophy occurs in one out of 8,000 people, though type 2 accounts for only two percent of those cases. While myotonic dystrophy type 1 is the most prevalent form, myotonic dystrophy type 2 is common amongst people with German ancestry.
Symptoms of Myotonic Dystrophy Type 2
Compared to myotonic dystrophy type 1, patients with myotonic dystrophy type 2 have milder symptoms. The hallmark symptoms of myotonic dystrophy type 2 is “progressive muscle wasting and weakness, particularly in the lower legs, hands, neck, and face,” according the NIH. Another common symptom is myotonia, which is uncontrolled tension in the muscles; as a result, patients have problems releasing their grip. Other symptoms include cataracts, cardiac conduction defects, hypogammaglobulinemia, and insulin insensitivity. In male patients, primary gonadal failure is a possible symptom.
The NIH states that the difference between myotonic dystrophy type 1 and myotonic dystrophy type 2 is the mutated gene. With myotonic dystrophy type 2, the mutated gene is CNBP; no other disorder is connected to an altered CNBP gene. Also called CCHC-type zinc finger, nucleic acid binding protein, it produces proteins that work in the heart and the skeletal muscles; however, the NIH notes that the exact function of the CNBP gene is not known. The cytogenetic location of the CNBP gene is 3q21.
Treatment of Myotonic Dystrophy Type 2
Although myotonic dystrophy type 2 cannot be cured, the NIH states that the treatments of the disorder can help patients manage symptoms. With myotonia, treatment is not always needed; however, myotonic dystrophy type 2 patients are recommended to participate in physical activity to maintain strength and reduce musculoskeletal pain. If patients are experiencing muscle weakness, assistive devices, like ankle-foot orthoses and wheelchairs, can be used. Vision problems can be rectified with a removal of cataracts, and arrhythmias can be treated with defibrillator placement.
Since pain is a prevalent symptom in myotonic dystrophy type 2, medications are often prescribed. Mexiletene is an anesthetic, similar to lidocaine except taken orally; the NIH adds mexiletene can be used to treat arrhythmia. While classified as an anticonvulsant, gabapentin can also treat pain, according to the NIH. Tricyclic antidepressants are also given for myotonic dystrophy type 2. Non-steroidal anti-inflammatory drugs (NSAIDs), like ibuprofen and acetaminophen, are over-the-counter options, though prescription versions are also available. Other pain medication options include low-dose thyroid replacement and low-dose steroids.