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Gilbert Gottfried's Myotonic Dystrophy

— The genetic condition that claimed the life of the acclaimed comedian

MedpageToday
A photo of Gilbert Gottfried performing on stage.

Gilbert Gottfried, a stand-up comedian who liked to push the envelope when it came to political correctness, passed away this week at the age of 67.

Best known for his distinctive voice, both as the Aflac duck and as the wisecracking parrot Iago in the animated Disney film "Aladdin," Gottfried was a cast member on "Saturday Night Live" for a year and was featured in many films, such as "Beverly Hills Cop II," "Look Who's Talking II," and "The Aristocats."

His family wrote on : "We are heartbroken to announce the passing of our beloved Gilbert Gottfried after a long illness ... Although today is a sad day for all of us, please keep laughing as loud as possible in Gilbert's honor."

Gottfried's longtime friend and publicist, Glenn Schwartz, later clarified that Gottfried had the rare genetic muscle disorder myotonic dystrophy type 2 for many years and had passed due to recurrent ventricular tachycardia.

Myotonic Dystrophy

Myotonic dystrophy is an inherited disease that affects the muscles as well as other body systems. It affects at least one in 8,000 people worldwide and is the most common form of muscular dystrophy that begins in adulthood, often in a person's 20s or 30s.

The condition may be classified into two types: myotonic dystrophy type 1 (DM1), sometimes called "Steinert disease," and myotonic dystrophy type 2 (DM2). DM1, the more prevalent of the two, appears to involve type 1 (slow-twitch) muscle fibers, whereas DM2 is involved with type 2 (fast-twitch) muscle fibers.

DM1 comes in mild, classic, or congenital forms that are characterized by increasing severity of muscle weakness and disability, among other factors.

The DM2 that Gottfried had is characterized by muscle weakness, wasting, and pain, as well as myotonia. Proximal muscles such as those in the neck, fingers, elbows, and hips are typically affected, whereas facial and ankle muscles are less commonly involved. Less common symptoms of DM2 include abnormalities of the cardiac conduction defects, cataracts (especially posterior subcapsular cataracts before age 50), excessive daytime sleepiness, and diabetes. Males may experience balding and infertility.

DM2 symptoms usually develop in a person's 20s to 40s. DM2 is generally considered less severe than DM1 -- though symptoms may vary among patients -- and those affected commonly have a normal life span.

While the rate of progression can vary among affected people, symptoms generally progress slowly. Although mobility may be impaired at an earlier age, the ability to walk is often retained until around 60 years of age. The prognosis for those affected can depend on the extent of cardiac involvement.

Treatment

There is currently no treatment available to stop or slow the progression of DM2. Management is determined by an individual's symptoms, and may include:

  • Ankle-foot braces, wheelchairs, or other assistive devices as needed for muscle weakness
  • Defibrillator placement may be needed for arrhythmias
  • Cataracts can be removed for those with impaired vision
  • Testosterone replacement therapy may be useful for hypogonadism in males

Myotonia is usually mild and rarely requires treatment. Routine exercise appears to help with pain control, as well as with muscle strength and endurance.

The effectiveness of most medications for pain management varies. The antiarrhythmic drug , which is very effective for some forms of myotonia, has helped control muscle pain in some people with this condition. Other medications that have been used with some success include gabapentin, nonsteroidal anti-inflammatory drugs (NSAIDS), low-dose thyroid replacement, low-dose steroids, and tricyclic antidepressants. Cholesterol-lowering medications should be avoided when they are associated with increased weakness.

Consensus-based care recommendations for adults with DM2 proposed by the Myotonic Dystrophy Foundation can be found .

Genetic Inheritance

DM1 and DM2 are inherited in an autosomal dominant pattern, with one copy of the gene being sufficient to cause the disorder.

Both types of myotonic dystrophy are caused by a mutation called a CTG (cytosine, thymine, guanine) trinucleotide repeat in the DMPK gene. This trinucleotide is repeated multiple times in a row. When this happens more than 34 times, it creates an unstable region in the gene. Patients with 35-49 repeats, considered to be premutations, do not have symptoms themselves, but their children are at increased risk of inheriting a larger repeat size and thus having symptoms.

The protein made by the DMPK gene is believed to play a role in communication and impulse transmission within and between cells. It is particularly important for the correct functioning of cells in the heart, brain, and skeletal muscles. The abnormal number of CTG repeats leads to the creation of longer mRNAs, which can disable important proteins. This prevents the normal function of cells in muscles and other tissues.

Both DM1 and DM2 exhibit a phenomenon called anticipation: As the gene is passed down, the next generation sees the disorder generally beginning earlier in life, and signs and symptoms becoming more severe.

Michele R. Berman, MD, is a pediatrician-turned-medical journalist. She trained at Johns Hopkins, Washington University in St. Louis, and St. Louis Children's Hospital. Her mission is both journalistic and educational: to report on common diseases affecting uncommon people and summarize the evidence-based medicine behind the headlines.