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Genetic and Rare Diseases Information Center (GARD)

Congenital fiber type disproportion

Other Names for this Disease
  • Congenital fiber-type disproportion myopathy
  • Myopathy, congenital with fiber-type disproportion
  • Fiber-type disproportion myopathy, congenital
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Your Question

My child has congenital fiber type disproportion due to a mutation in SEPN1. Are there any new drugs or vitamins (even under trial) to treat this condition. 

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is congenital fiber type disproportion?

Congenital fiber type disproportion is a type of congenital myopathy. Congenital myopathy refers to a group of muscle disorders that appear at birth or in infancy. Early signs and symptoms of congenital fiber type disproportion include floppiness, limb and facial weakness, and breathing problems.[1][2] It is a genetic disease caused by mutations in the ACTA1, SEPN1RYR1 or TPM3 genes.[1] Depending on the gene and mutation involved, congenital fiber type disproportion can be passed through families in an autosomal recessive, autosomal dominant, or X-linked manner.[1][3]
Last updated: 9/5/2012

What is SEPN1 and how does it affect the growth and development of muscles?

The SEPN1 gene provides instructions for making a protein called "selenoprotein N." This protein is part of a family of selenoproteins, which have several critical functions within cells. Selenoproteins are involved in chemical reactions, which are essential for storing and releasing energy. Proteins in this family also help process hormones produced by the thyroid. The exact function of selenoprotein N is unknown. This protein is highly active in many tissues before birth and may be involved in the formation of muscle tissue. Selenoprotein N may also be important for normal muscle function after birth, although it is active at much lower levels in adult tissues. The protein contains a region that likely allows it to bind to calcium. This region is of interest because calcium plays an important role in triggering muscle contractions, which allow the body to move.[1]
Last updated: 4/29/2010

Are there any new therapies, medications, or supplements to cure or treat congenital fiber type disproportion?

Currently we are not aware of new therpies, drugs, supplements, or vitamins to cure or effectively treat congenital fiber-type disproportion. Supportive treatment may involve orthopedic treatments, as well as physical, occupational or speech therapy.[2] You can find additional information on the management of congenital fiber type disproportion at the following link to the GeneReviews Web site. GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
Last updated: 4/30/2010

How can I learn more about research studies involving congenital fiber type disproprotion?

The Beggs laboratory at Children’s Hospital in Boston is conducting research studies involving congenital myopathies, including congenital fiber type disproportion. The primary goal of this research is to better understand the genes and proteins involved in muscle functioning and disease. These studies will lead to an improved understanding of the causes of congenital myopathy and allow for improved diagnosis and treatment.

You can find additional information on congenital fiber type disproportion as well as instructions on how to participate in the Beggs laboratory research trial at the following Web site.

The National Institutes of Health, through the National Library of Medicine, developed to provide patients, family members, and members of the public with current information on clinical research studies. While no studies involving congenital fiber type disproportion specifically are listed at this time, there are a few studies enrolling children with congenital myopathies in general. To find these trials, click on the link above and use "congenital myopathy" as your search term. After you click on a study, review its "eligibility" criteria to determine its appropriateness. Use the study’s contact information to learn more. Check this site often for regular updates. 

You can also contact the Patient Recruitment and Public Liaison (PRPL) Office at the National Institutes of Health (NIH). We recommend calling the toll-free number listed below to speak with a specialist, who can help you determine if your child is eligible for any clinical trials.

Patient Recruitment and Public Liaison Office (PRPL)
NIH Clinical Center
Bethesda, Maryland 20892-2655
Toll-free: 800-411-1222
Fax: 301-480-9793
Web site:

If you are interested in enrolling your child in a clinical trial, you can find helpful general information on clinical trials at the following Web page.

A tutorial about clinical trials that can also help answer your questions can be found at the following link from the National Library of Medicine.

Resources on many charitable or special-fare flights to research and treatment sites and low-cost hospitality accommodations for outpatients and family members, as well as ambulance services, are listed on the Web site of the Office of Rare Diseases Research (ORDR), part of the National Institutes of Health.

In addition, the Research Portfolio Online Reporting Tool (RePORT) provides access to reports, data, and analyses of research activities at the National Institutes of Health (NIH), including information on NIH expenditures and the results of NIH-supported research.  Although these projects may not conduct studies on humans, you may want to contact the investigators to learn more. Currently no studies involving congenital fiber-type disproportion are listed, however there are a number of studies involving congenital myopathies in general. To search for studies, click on the link and enter "congenital myopathy” in the search box.  Then click “Submit Query”. Review the study information to determine it relevance. You can contact the researchers for further details regarding a study.

In addition we searched RePORT using "selenoprotein" as our search term. By doing so we identified the following trials which are investigating further the role of selenoproteins in health and disease:

Title: An Unexpected Role for ELF4A3 in Regulating GPX1 Selenoprotein Expression
Priniciple Investigator: Michael Everest Budiman
Cleveland Clinic

Title: Selenoprotein synthesis: Redefinition of Selenocysteine-Encoding UGA Codons
Principle Investigator: Michael Howard
University of Utah

Last updated: 4/29/2010

Other Names for this Disease
  • Congenital fiber-type disproportion myopathy
  • Myopathy, congenital with fiber-type disproportion
  • Fiber-type disproportion myopathy, congenital
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.