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Disease Profile

Childhood-onset nemaline myopathy

Prevalence
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.
<1 / 1 000 000

< 331

US Estimated

< 514

Europe Estimated

Age of onset

Childhood

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ICD-10

G71.2

Inheritance

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

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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

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X-linked
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.

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

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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.

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Not applicable

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Other names (AKA)

Mild nemaline myopathy

Categories

Congenital and Genetic Diseases; Nervous System Diseases

Summary

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.
orphanet

Orpha Number: 171439

Definition
Childhood onset nemaline myopathy, or mild nemaline myopathy is a type of nemaline myopathy (NM; see this terms) characterized by distal muscle weakness, and sometimes slowness of muscle contraction.

Epidemiology
The annual incidence of NM has been estimated at 1/50,000 live births.

Clinical description
Childhood onset NM might represent 10-15% of total cases. Onset is around 10 years of age, with initial presentation of symmetric weakness of ankle dorsiflexion and foot drop, or a general slowness of muscle contraction. All movements at the ankle and more proximal limb muscles may be disturbed. Weakness is slowly progressive. Facial, respiratory and cardiac muscles are generally normal, but patients are unable to jump or run because of muscle weakness or slowness.

Etiology
This form of NM is caused by mutations in the ACTA1 (1q42.13), NEB (2q22), TPM2 (9p13.3) or TPM3 (1q21.2) genes, and its transmission follows an autosomal dominant pattern.

Visit the Orphanet disease page for more resources.

Symptoms

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:
HPO ID
80%-99% of people have these symptoms
EMG: myopathic abnormalities
0003458
Nemaline bodies
0003798
30%-79% of people have these symptoms
Bradykinesia
Slow movements
Slowness of movements

[ more ]

0002067
Clumsiness
0002312
Difficulty walking
Difficulty in walking
0002355
Exercise intolerance
Decreased ability to exercise
Inability to exercise

[ more ]

0003546
Generalized limb muscle atrophy
Generalized muscle wasting
0009055
Hyporeflexia
Decreased reflex response
Decreased reflexes

[ more ]

0001265
Increased muscle lipid content
Fat accumulation in muscle fibers
Fat deposits in muscle fibers
Lipid accumulation in skeletal muscle
Skeletal muscle lipid accumulation

[ more ]

0009058
Increased variability in muscle fiber diameter
0003557
Limb muscle weakness
Limb weakness
0003690
Motor delay
0001270
Muscle stiffness
0003552
Neuromuscular dysphagia
0002068
Spinal rigidity
Reduced spine movement
0003306
Type 1 muscle fiber predominance
0003803
5%-29% of people have these symptoms
Areflexia
Absent tendon reflexes
0001284
Breech presentation
Feet or buttocks of fetus positioned near opening of uterus
0001623
Bulbar signs
0002483
Cardiomyopathy
Disease of the heart muscle
0001638
Facial diplegia
0001349
Fatigable weakness of bulbar muscles
0030192
Feeding difficulties
Feeding problems
Poor feeding

[ more ]

0011968
Fetal akinesia sequence
0001989
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

0001290
High palate
Elevated palate
Increased palatal height

[ more ]

0000218
Hypertelorism
Wide-set eyes
Widely spaced eyes

[ more ]

0000316
Long face
Elongation of face
Increased height of face
Increased length of face
Vertical elongation of face
Vertical enlargement of face
Vertical overgrowth of face

[ more ]

0000276
Micrognathia
Little lower jaw
Small jaw
Small lower jaw

[ more ]

0000347
Mildly elevated creatine kinase
0008180
Narrow chest
Low chest circumference
Narrow shoulders

[ more ]

0000774
Narrow face
Decreased breadth of face
Decreased width of face

[ more ]

0000275
Neck muscle weakness
Floppy neck
0000467
Pes cavus
High-arched foot
0001761
Reduced vital capacity
0002792
Respiratory insufficiency due to muscle weakness
Decreased lung function due to weak breathing muscles
0002747
Scapular winging
Winged shoulder blade
0003691
Scoliosis
0002650
Slender build
Thin build
0001533
Waddling gait
'Waddling' gait
Waddling walk

[ more ]

0002515
1%-4% of people have these symptoms
Arthrogryposis multiplex congenita
0002804
Polyhydramnios
High levels of amniotic fluid
0001561
Ptosis
Drooping upper eyelid
0000508

Diagnosis

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

Treatment

The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your healthcare professional.

Management Guidelines

  • Orphanet Emergency Guidelines is an article which is expert-authored and peer-reviewed that is intended to guide health care professionals in emergency situations involving this condition.

Learn more

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.

Where to Start

  • Genetics Home Reference (GHR) contains information on Childhood-onset nemaline myopathy. This website is maintained by the National Library of Medicine.

In-Depth Information

  • 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.
  • 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.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Childhood-onset nemaline myopathy. Click on the link to view a sample search on this topic.