Hereditary Inclusion Body Myopathies
Inclusion body myopathy 2 is a hereditary condition that mostly affects skeletal muscles, which are muscles that the body uses for movement. This disorder causes muscle weakness that appears in late adolescence or early adulthood and only worsens over time (O 'Ferrall). GNE-related myopathy, also known as inclusion body myopathy 2, is characterized by slowly progressive distal muscle weakness that begins with gait disturbance and foot drop secondary to anterior tibialis muscle weakness. Weakness eventually includes the hand and thigh muscles but commonly spares the quadriceps muscles, even in advanced disease. Affected individuals are usually wheelchair bound about twenty years after onset. If quadriceps sparing is incomplete, loss of the ability to walk tends to occur earlier ("Inclusion Body Myopathy 2.").
More than 200 people with inclusion body myopathy 2 have been reported. Iranian Jewish descent appears more common among carriers; the condition affects an estimated 1 in 1,500 people in this population. Additionally, at least 15 people in the Japanese population have been diagnosed with this disorder (O’Ferrall).
The diagnosis of GNE-related myopathy is based on clinical and histopathologic criteria. Because simplex cases (i.e. a single occurrence in a family) are common, the presence of affected relatives is not necessary for diagnosis. Muscle histopathology typically shows rimmed vacuoles and characteristic filamentous inclusions. GNE, which encodes the bifunctional enzyme UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase, is the only gene in which mutations are known to cause GNE-related myopathy (O’Ferrall). Molecular genetic testing is available on a clinical basis.
Treatment is symptomatic. Individuals are often evaluated and managed by a multidisciplinary team including neurologists, geneticists and physiatrists, as well as physical and occupational therapists. Annual routine follow up with the multidisciplinary team,
More than 200 people with inclusion body myopathy 2 have been reported. Iranian Jewish descent appears more common among carriers; the condition affects an estimated 1 in 1,500 people in this population. Additionally, at least 15 people in the Japanese population have been diagnosed with this disorder (O’Ferrall).
The diagnosis of GNE-related myopathy is based on clinical and histopathologic criteria. Because simplex cases (i.e. a single occurrence in a family) are common, the presence of affected relatives is not necessary for diagnosis. Muscle histopathology typically shows rimmed vacuoles and characteristic filamentous inclusions. GNE, which encodes the bifunctional enzyme UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase, is the only gene in which mutations are known to cause GNE-related myopathy (O’Ferrall). Molecular genetic testing is available on a clinical basis.
Treatment is symptomatic. Individuals are often evaluated and managed by a multidisciplinary team including neurologists, geneticists and physiatrists, as well as physical and occupational therapists. Annual routine follow up with the multidisciplinary team,
Cited: "Inclusion Body Myopathy 2." - Genetics Home Reference. N.p., n.d. Web. 26 Mar. 2013. Malicdan MC, Noguchi S, Nishino I. Perspectives on distal myopathy with rimmed vacuoles or hereditary inclusion body myopathy: contributions from an animal model. Lack of sialic acid, a central determinant in sugar chains, causes myopathy? Acta Myol. 2007 Dec;26(3):171-5. Review. PubMed citation Malicdan MC, Noguchi S, Nishino I. Recent advances in distal myopathy with rimmed vacuoles (DMRV) or hIBM: treatment perspectives. Curr Opin Neurol. 2008 Oct;21(5):596-600. doi: 10.1097/WCO.0b013e32830dd595. Review. PubMed citation Nishino I, Malicdan MC, Murayama K, Nonaka I, Hayashi YK, Noguchi S. Molecular pathomechanism of distal myopathy with rimmed vacuoles. Acta Myol. 2005 Oct;24(2):80-3. Review. PubMed citation O 'Ferrall, Erin K. "Summary." GNE-Related Myopathy. U.S. National Library of Medicine, 26 Mar. 2004. Web. 26 Mar. 2013. "Parallels between Inclusion Body Myositis (IBM) and Alzheimer 's." Parallels between Inclusion Body Myositis (IBM) and Alzheimer 's. N.p., n.d. Web. 26 Mar. 2013