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In general, muscular dystrophies cause wasting and weakening of muscles. In limb-girdle muscular dystrophies the muscles in the shoulder and pelvic girdle (the large muscles around the top part of the arms and legs) are most affected. Early symptoms of limb-girdle muscular dystrophies include difficulty with running, climbing stairs, standing, and walking. As the disease progresses, it may become difficult for some patients to do activities that require the arms to be raised for a duration (e.g., combing hair).
In Myoshi myopathy, early symptoms are most pronounced in the distal parts of the legs (i.e., the calf muscles). Patients experience weakness and atrophy in these muscles which may make it difficult for them to stand on tiptoe. As the disease progresses the muscle weakness and atrophy may spread to the thighs and gluteal muscles, forearms, and shoulder girdle muscles, which can result in additional symptoms including difficulty climbing stairs, standing, and walking, as well as a decrease in grip strength.
Symptoms in both Myoshi myopathy and limb-girdle muscular dystrophy type 2B may affect one side more than the other. While these conditions differ in the initial distribution of muscle involvement, as they progress there is little clinical difference between them. There is no significant difference in the rate of progression between them and progression is typically slow.
In a recent study of 40 patients with dysferlin gene mutations by Nguyen et al., 50% of the patients were diagnosed as having typical Miyoshi myopathy or Limb-girdle muscular dystrophy type 2B. Unusual phenotypes included a mixed phenotype, which the authors referred to as "proximodistal." Thirty-five percent of the patients had this phenotype and had a combination of distal and proximal onset. Two other phenotypes included a "pseudometabolic myopathy" and "asymptomatic hyperCKemia" which were found in 10% and 5% of the patients respectively.
- Nguyen K. Phenotypic study in 40 patients with dysferlin gene mutations: High frequency of atypical phenotypes. Arch Neurol. 2007;
- Bushby KMD, Straub V, Lochmuller H, Eagle M, Guglieri M, Hastings L. Limb girdle muscular dystrophy. Muscular Dystrophy Campaign. http://mdausa.org/disease/limb-girdle-muscular-dystrophy/overview. Accessed 2/18/2008.
- Limb-Girdle Muscular Dystropy. The Muscular Dystrophy Association. http://mda.org/disease/limb-girdle-muscular-dystrophy. Accessed 1/1/1900.
- Aoki M. Dysferlinopathy. GeneReviews. 2004; http://www.ncbi.nlm.nih.gov/books/NBK1303/. Accessed 2/18/2008.
- Ueyama H. et al. Clinical heterogeneity in dysferlinopathy. Internal Medicine. 2002;