X-Linked Myotubular Myopathy
National Organization for Rare Disorders, Inc.
It is possible that the main title of the report X-Linked Myotubular Myopathy is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.
X-linked myotubular myopathy (XLMTM) is a rare genetic neuromuscular disorder that is characterized by muscle weakness that can range from mild to profound. Symptoms are often present at birth, but may first develop during infancy or early childhood. In rare cases, symptoms may not develop until later, even adulthood. Common symptoms include mild to profound muscle weakness, diminished muscle tone (hypotonia or "floppiness"), feeding difficulties, and potentially severe breathing complications (respiratory distress). Feeding difficulties and respiratory distress develop because of weakness of the muscles that are involved in swallowing and breathing. The overall severity of the disorder can range from mildly affected individuals to individuals who develop severe, life-threatening complications during infancy and early childhood. Most affected individuals have a severe form of the disorder and respiratory failure is an almost uniform occurrence. XLMTM is caused by mutations to the myotubularin (MTM1) gene. The disorder is inherited as an X-linked recessive condition. The disorder predominantly affects males, but female carriers can develop mild symptoms. In rare specific cases, females can develop a severe form similar to that seen in males.
XLMTM belongs to a larger group of disorders known as the centronuclear myopathies. In addition to XLMTM, there are forms of centronuclear myopathy that are inherited as autosomal dominant or autosomal recessive conditions. Generally, the autosomal forms are less severe than XLMTM, however, in rare cases, individuals with an autosomal form can develop severe complications that are similar to those seen in XLMTM. Centronuclear myopathies derive their name from the abnormal location of the nucleus in the center of the muscle fiber (muscle cell) rather than its normal position on the edge. Additional pathologic features include disorganized perinuclear organelles and abnormalities in oxidative staining patterns. Centronuclear myopathies can be further classified into the larger, broader category of congenital myopathy, a group of genetic muscle disorders that are present at birth.
In the medical literature, centronuclear myopathy is generally used for the autosomal forms of the disorder and myotubular myopathy is generally used for the X-linked form. Distinguishing between the X-linked (myotubular) form and the autosomal forms is essential as the symptoms are usually more severe in the X-linked form. NORD has a separate report on centronuclear myopathy that describes the autosomal forms in greater detail. This report specifically deals with X-linked centronuclear (myotubular) myopathy.
CLIMB (Children Living with Inherited Metabolic Diseases)
176 Nantwich Road
Crewe, CW2 6BG
Myotubular Myopathy Resource Group
2602 Quaker Drive
Texas City, TX 77590
Contact A Family
209-211 City Road
London, EC1V 1JN
Muscular Dystrophy Association
3300 East Sunrise Drive
Tucson, AZ 85718-3208
Muscular Dystrophy Campaign
61 Southwark Street
London, SE1 0HL
NIH/National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
European Alliance of Neuromuscular Disorders Associations
MDG Malta 4
Gzira, GAR 04
Genetic and Rare Diseases (GARD) Information Center
PO Box 8126
Gaithersburg, MD 20898-8126
Cure CMD (Congenital Muscular Dystrophy)
P.O. Box 701
Olathe, KS 66051
Joshua Frase Foundation
222 Forbes Rd.
Braintree, MA 02184
15a Barnard Road
London SW11 1QT
Tel: 07518 113692
For a Complete Report
This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to www.rarediseases.org and click on Rare Disease Database under "Rare Disease Information".
The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.
It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report
This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.
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Last Updated: 3/19/2013
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