What are the other Names for this Condition? (Also known as/Synonyms)

• Autosomal Dominant Myotubular Myopathy 
• Centronuclear Myopathy 1
• DNM2-Related Centronuclear Myopathy

What is Autosomal Dominant Centronuclear Myopathy? (Definition/Background Information)

• Autosomal Dominant Centronuclear Myopathy (AD-CNM) is a type of centronuclear myopathy, which is a group of rare, inherited conditions that affect the muscles
• In AD-CNM, specifically, the severity of the condition and the associated signs and symptoms vary significantly among affected people
• In people with a mild form, features of the condition generally do not develop until adolescence or early adulthood and may include slowly progressive muscle weakness, muscle pain with exercise and difficulty walking. Although some affected people will eventually lose the ability to walk, this usually does not occur before the 6th decade of life
• In more severe cases, affected people may develop symptoms during infancy or early childhood such as hypotonia and generalized weakness. These children generally have delayed motor milestones and often need wheelchair assistance in childhood or adolescence. 
• Most cases of Autosomal Dominant Centronuclear Myopathy are caused by changes (mutations) in the DNM2 gene; however, some affected families are reported to have mutations in the MYF6 or CCDC78 genes. The condition is inherited in an autosomal dominant manner
• Treatment is based on the signs and symptoms present in each person and may include physical and/or occupational therapy and assistive devices to help with mobility, eating and/or breathing

(Source: Autosomal Dominant Centronuclear Myopathy; Genetic and Rare Disease Information Center (GARD) of National Center for Advancing Translational Science (NCATS), USA.)

Who gets Autosomal Dominant Centronuclear Myopathy? (Age and Sex Distribution)

• Autosomal Dominant Centronuclear Myopathy is a rare congenital disorder. The presentation of symptoms may occur in infancy, or during early childhood in those with severe forms of the disorder. It may also occur later in life, if AD-CNM is mild
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Autosomal Dominant Centronuclear Myopathy? (Predisposing Factors)

• A positive family history may be an important risk factor, since Autosomal Dominant Centronuclear Myopathy can be inherited

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Autosomal Dominant Centronuclear Myopathy? (Etiology)

• Most cases of Autosomal Dominant Centronuclear Myopathy are caused by changes (mutations) in the DNM2 gene
• However, some affected families are reported to have mutations in the MYF6 or CCDC78 genes
• The condition is inherited in an autosomal dominant manner

(Source: Autosomal Dominant Centronuclear Myopathy; Genetic and Rare Disease Information Center (GARD) of National Center for Advancing Translational Science (NCATS), USA.)

Autosomal dominant mode of inheritance: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.

What are the Signs and Symptoms of Autosomal Dominant Centronuclear Myopathy?

The signs and symptoms of Autosomal Dominant Centronuclear Myopathy may vary among affected individuals in type and severity, and may include the following:

• Skeletal muscle hypertrophy
• Areflexia
• Centrally nucleated skeletal muscle fibers
• Easy fatigability
• External ophthalmoplegia
• Facial palsy
• Flexion contracture
• Motor delay
• Proximal muscle weakness
• Sleepy facial expression

(Source: Autosomal Dominant Centronuclear Myopathy; Genetic and Rare Disease Information Center (GARD) of National Center for Advancing Translational Science (NCATS), USA.)

How is Autosomal Dominant Centronuclear Myopathy Diagnosed?

Autosomal Dominant Centronuclear Myopathy is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Autosomal Dominant Centronuclear Myopathy?

The complications of Autosomal Dominant Centronuclear Myopathy may include:

• Delay in motor development
• Severe muscle pain
• Problems with movement; necessity for wheelchair assistance

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Autosomal Dominant Centronuclear Myopathy Treated?

There is no cure for Autosomal Dominant Centronuclear Myopathy, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complication that develops.

How can Autosomal Dominant Centronuclear Myopathy be Prevented?

Autosomal Dominant Centronuclear Myopathy may not be preventable, since it is a genetic disorder.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders
• Regular medical screening at periodic intervals with tests and physical examinations are recommended

What is the Prognosis of Autosomal Dominant Centronuclear Myopathy? (Outcomes/Resolutions)

• The prognosis of Autosomal Dominant Centronuclear Myopathy is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information Autosomal Dominant Centronuclear Myopathy:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/