| | |
|
 | |
 
Healthcare Provider Info
> DMD OMIM
> BMD OMIM
> Myotubular Myopathy OMIM
> LGMD OMIM
> Centronuclear Myopathy OMIM
> Myotonic Dystrophy OMIM
> Miyoshi Myopathy OMIM
> FSHD OMIM
> Link to Diagnostic Text Book Chapters

Enroll a Patient
  Many families are interested in supporting our research. Click here to find out how you can help.
 
   
Need Assistance?
  Contact our on-staff research genetic counselor
 
   
Investigators
  Louis Kunkel, PhD
  Robert Brown, MD
  Alan Beggs, PhD
  Emanuela Gussoni, PhD
  Elizabeth Engle, MD
  Isaac Kohane, MD, PhD
   
Miyoshi Myopathy
   

Inheritance: Autosomal Recessive
Genetic Alteration: Dysferlin Gene, 2p12-14
Incidence: Because this group of diseases is so variable, an incidence cannot be estimated.
Onset: Late onset, childhood through adulthood
Muscles Affected: Voluntary muscles of the calves and arms
 

Miyoshi myopathy is an inherited muscle disease in which the earliest involvement is in voluntary (skeletal and striated) muscles that are distal, or farther away from the trunk of the body.

Miyoshi myopathy is allelic with LGMD2B. We do not understand why a defect in the same gene produces Miyoshi myopathy in some individuals and limb-girdle dystrophy in others. This difference can even appear within the same family.
  Miyoshi Myopathy

Autosomal Recessive Diagram

Inheritance Diagram
  Clinical Picture
Miyoshi myopathy has only been identified and researched for a few years in the United States. It was first recognized in Japan in the early 1980’s. The disease typically begins focally in the distal leg muscles (particularly the calves). An early manifestation is difficulty standing on the toes or running. Over many years, the disease slowly spreads to involve proximal as well as distal muscles. The arms may become involved. The heart, lungs, and brain generally are not affected. Many Miyoshi patients require the use of wheelchairs after several years. Fortunately, though, despite significant weakness, these individuals live well into mature adulthood. It is not yet possible to predict the course that Miyoshi myopathy will take in an individual. But we do know that it is not a fatal disease.


What causes Miyoshi Myopathy
The cause of this disorder is a genetic alteration in the dysferlin gene on chromosome 2. This locus is allelic with limb-girdle muscular dystrophy type 2. The pathophysiology is related to the dysferlin protein, which is attached to the sarcolemma.

Ways a person gets Miyoshi Myopathy
  1. Inheritance of the genetic alteration from the parents, in an autosomal recessive pattern
  2. Sporadic Mutations
  3. There is genetic heterogeneity and some families have linked to chromosome 10 and other loci.


Diagnosing Miyoshi Myopathy

  • Take a detailed patient and family history (3 generation pedigree)
  • Determine the source of the muscle weakness (nerve or muscle)
  • Detailed exam to look for certain signs of Miyoshi myopathy: weakness/wasting in the posterior legs (gastrocnemius, soleus), symmetric involvement, involvement of arms & proximal muscles late in disease progression, calf wasting
  • Schedule a muscle biopsy
  • Genetic testing

Laboratory:

  • CK levels tend to be very high (up to 20,000)
  • There is selective involvement of hamstring, gastrocnemius & soleus
  • Early muscle edema
  • Muscle biopsy shows dystrophic muscle and necrosis & degeneration of muscle fibers. There is fiber size variation and fiber splitting
  • Endomysial connective tissue is increased in more involved muscles
  • Perimysial & perivascular cell infiltrates may occur in some muscles, leading to inflammation

Genetic Testing
Genetic testing is not yet available for Miyoshi myopathy on a routine clinical basis. However, it is usually available on a research basis. For more information on this testing, contact the Day Laboratory for Neuromuscular Research.

Support

After your patient is diagnosed with Miyoshi myopathy, he or she is likely to feel overwhelmed. It may be helpful to let your patient know that support is available. Contact your local Muscular Dystrophy Association Clinic for more information, or visit the web site at www.mdausa.org. Additionally, visit the Links section on this Web site to learn more about other support and information.

  Website Terms & Disclamer • Web Master • Privacy Policy • Datasharing
Developed by CreationProject