Diagnosis

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Electromyography or (EMG). This procedure determines if nerve or muscle cells are damaged. Since a common symptom of Nemaline Myopathy is muscle weakness this allows doctors to determine where and why the weakness is occurring.[1]

MRI of the Musculoskeletal System. MRI uses a magnetic field to take pictures of body structures and allows physicians to determine if a patient has a certain disease. [2]

Needle biopsy A needle biopsy allows a physician to test specific cells in the body. These cells are sent to a laboratory to undergo testing and can further determine why muscle weakness throughout the body could be occurring. This testing can confirm that muscle cells contain rod like structures [3]

Causes

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Nemaline Myopathy is caused by mutations in one of many different genes. Genes make proteins that allow muscle cells to work. In muscle cells, proteins are found in structures called sarcomeres. Sarcomeres allow muscle cells to contract or tense up. Patients with nemaline myopathy have abnormal sarcomeres. The sarcomeres contain abnormal structures called nemaline bodies. Nemaline bodies are rod shaped structures, and this results in the many names for nemaline myopathy. [4]

The two most common gene mutations causing nemaline myopathy are mutations on NEB or ACTA1. Mutations of the NEB gene usually result in symptoms present at birth or beginning in early childhood. This mutation results in about 50% of affected nemaline myopathy patients. Mutations of the ACTA1 gene the onset age and range of symptoms varies. This mutation results in about 15 to 25 percent of nemaline myopathy patients. The reason this is lower is because mutations in the ACTA1 gene would usually not be passed down from parents, this mutation happens spontaneously in the egg or sperm. [5]

The most common cases of nemaline myopathy are inherited in a pattern of autosomal recessive. This means that a patient must be homozygous recessive in a gene that causes nemaline myopathy. In very few cases, nemaline myopathy can be caused by a pattern of autosomal dominance. The risk of all cases of nemaline myopathy is the same in males and females. [6]

History

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add to current history part Nemaline Myopathy was discovered as a cause for muscle weakness in 1963 by Shy. Shy and his team discovered rod- like structures in muscle fibers of patients with muscle weakness by performing muscle biopsies on multiple patients. [7]

Sources

1. https://www.mda.org/disease/inherited-and-endocrine-myopathies/types/nemaline-myopathy

2. http://ghr.nlm.nih.gov/condition/nemaline-myopathy

3. https://www.nlm.nih.gov/medlineplus/muscledisorders.html

4. http://rarediseases.org/rare-diseases/nemaline-myopathy/

5. http://www.sciencedirect.com/science/article/pii/S0887899415300199

6. http://www.sciencedirect.com/science/article/pii/S1071909111000891

7. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3185829/

8. http://www.ncbi.nlm.nih.gov/pubmed/22172418

9. http://www.socialstyrelsen.se/rarediseases/nemalinemyopathy#anchor_7m