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Disease Profile

Muscular dystrophy, congenital, merosin-positive

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable



The congenital muscle dystrophies are currently classified according to the genetic defects. Historically, congenital muscular dystrophies were classified in two broad groups: Classic CMD (which included the Merosin-deficient CMD and the Merosin-positive CMD) and the CMD with central nervous system (CNS) abnormalities (Fukuyama CMD, muscle-eye-brain disease and Walker-Warburg syndrome). Therefore, merosin-positive congenital muscle dystrophy (CMD) is now considered an old term which refers to a group of diseases without structural brain abnormalities that are caused by a variety of gene mutations, resulting in protein defects that do not affect the merosin protein. It usually has a milder phenotype than the merosin-negative CMD dystrophy group and includes, among others:[1]

Classic CMD without distinguishing features
Rigid spine syndrome associated with mutations in the selenoprotein N1 gene (SEPN1)
CMD with hyperextensible distal joints (Ullrich type)
CMD with intellectual disability or sensory abnormalities.

The pattern of muscle weakness and wasting in the patients within this group of congenital muscular dystrophy conditions is worse in the proximal upper limb-girdle and trunk muscles. Lower limb muscles may be mildly involved. Muscle biopsy shows a dystrophic pattern with normal staining for dystrophin, laminin alpha-2 of merosin and the sarcoglycans.[2]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
Percent of people who have these symptoms is not available through HPO
Autosomal recessive inheritance
Congenital muscular dystrophy
Congenital onset
Symptoms present at birth
Decreased fetal movement
Less than 10 fetal movements in 12 hours
Delayed ability to walk
Facial palsy
Bell's palsy
Flexion contracture
Flexed joint that cannot be straightened
Increased variability in muscle fiber diameter
Joint laxity
Joint instability
Lax joints

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Mildly elevated creatine kinase
Muscle tissue disease
Neck muscle weakness
Floppy neck
Neonatal hypotonia
Low muscle tone, in neonatal onset
Proximal muscle weakness
Weakness in muscles of upper arms and upper legs
Respiratory insufficiency due to muscle weakness
Decreased lung function due to weak breathing muscles
Shoulder girdle muscle weakness
Weak shoulder muscles
Variable expressivity


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

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    These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

    In-Depth Information

    • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
    • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 


      1. Darras BT. Oculopharyngeal, distal, and congenital muscular dystrophies. UpToDate. June 3, 2015; https://www.uptodate.com/contents/topic.do?topicKey=PEDS/6180.
      2. MUSCULAR DYSTROPHY, CONGENITAL, MEROSIN-POSITIVE. OMIM. July 22, 2005; https://omim.org/entry/609456?search=Congenital%20Muscular%20Dystrophy%2C%20Merosin%20Positive&highlight=congenital%20positive%20dystrophy%20merosin%20muscular. Accessed 6/19/2015.