Dysferlinopathy
Encyclopedia
Dysferlinopathy is an autosomal recessive neuromuscular disorder caused by a deficiency of functional dysferlin
protein due to mutations in the dysferlin gene. Dysferlinopathy is characterized by progressive muscle wasting and is most often clinically diagnosed as Limb-girdle muscular dystrophy
type 2B (LGMD2B) or Miyoshi muscular dystrophy 1 (MMD1; a type of distal muscular dystrophy
), depending on the initial pattern of muscle involvement at diagnosis. Dysferlinopathy is a rare disease whose exact incidence has not yet been determined.
of the limbs and the limb girdles (hips and shoulders), leaving critical muscles such as the heart and diaphragm largely unaffected. The majority of dysferlinopathy patients become non-ambulant within 10–20 years of diagnosis, but life expectancy is normal. There is a large amount of variability in the age of onset and progression of the disease.
Although LGMD2B and MMD1 are both caused by dysferlin deficiency, a diagnosis of LGMD2B is given when weakness initially presents in the proximal muscles (thighs and upper arms) while a diagnosis of MMD1 is given when weakness initially presents in the distal muscles (calves and lower arms). In both cases, weakness eventually progresses to include both distal and proximal muscles. Both LGMD2B and MMD1 are very difficult to diagnose, and patients are often misdiagnosed many times before they are successfully diagnosed with dysferlinopathy.
Dysferlin
Dysferlin also known as dystrophy-associated fer-1-like protein is a protein that in humans is encoded by the DYSF gene.Dysferlin is linked with skeletal muscle repair. A defect in the DYSF gene, located on chromosome 2p12-14, results in either of two types of muscular dystrophy; Miyoshi myopathy ...
protein due to mutations in the dysferlin gene. Dysferlinopathy is characterized by progressive muscle wasting and is most often clinically diagnosed as Limb-girdle muscular dystrophy
Limb-girdle muscular dystrophy
Limb-girdle muscular dystrophy or Erb's muscular dystrophy is an autosomal class of muscular dystrophy that is similar but distinct from Duchenne muscular dystrophy and Becker's muscular dystrophy...
type 2B (LGMD2B) or Miyoshi muscular dystrophy 1 (MMD1; a type of distal muscular dystrophy
Distal muscular dystrophy
Distal muscular dystrophy is a group of disorders characterized by onset in the hands or feet.Many types involve dysferlin, but it has been suggested that not all cases do.Types include:...
), depending on the initial pattern of muscle involvement at diagnosis. Dysferlinopathy is a rare disease whose exact incidence has not yet been determined.
Symptoms and Diagnosis
The symptoms of dysferlinopathy usually manifest in early adulthood between the ages of 16 and 25 and primarily affect the skeletal muscleSkeletal muscle
Skeletal muscle is a form of striated muscle tissue existing under control of the somatic nervous system- i.e. it is voluntarily controlled. It is one of three major muscle types, the others being cardiac and smooth muscle...
of the limbs and the limb girdles (hips and shoulders), leaving critical muscles such as the heart and diaphragm largely unaffected. The majority of dysferlinopathy patients become non-ambulant within 10–20 years of diagnosis, but life expectancy is normal. There is a large amount of variability in the age of onset and progression of the disease.
Although LGMD2B and MMD1 are both caused by dysferlin deficiency, a diagnosis of LGMD2B is given when weakness initially presents in the proximal muscles (thighs and upper arms) while a diagnosis of MMD1 is given when weakness initially presents in the distal muscles (calves and lower arms). In both cases, weakness eventually progresses to include both distal and proximal muscles. Both LGMD2B and MMD1 are very difficult to diagnose, and patients are often misdiagnosed many times before they are successfully diagnosed with dysferlinopathy.
External links
- GeneReviews/NCBI/NIH/UW entry on Dysferlinopathy including Miyoshi Distal Myopathy (Miyoshi Myopathy), Limb-Girdle Muscular Dystrophy Type 2B (LGMD2B)
- OMIM LGMD2B page
- OMIM MMD1 page
- Washington University, St. Louis: Neuromuscular Disease Center: Myopathy & Neuromuscular Disorders Differential Diagnosis
- The Jain Foundation is focused on finding a cure for this specific disease. The foundation is sponsoring targeted research and helping to educate patients on the importance of determining the mutations they carry in their dysferlin gene.
- Yahoo discussion group for dysferlinopathy patients