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Disease Profile

Autosomal dominant spinal muscular atrophy, lower extremity-predominant 2

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.

Unknown

Age of onset

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ICD-10

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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.

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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)

Autosomal dominant childhood-onset proximal spinal muscular atrophy with contractures; Lower extremity-predominant autosomal dominant proximal spinal muscular atrophy with contractures; SMALED2;

Summary

Autosomal dominant spinal muscular atrophy, lower extremity-predominant 2 (SMALED2) is a rare neurological disease characterized by early-childhood onset of muscle weakness and loss of muscle tissue (muscle atrophy), mostly affecting the muscles of the thighs. It is a subtype of the group of diseases known as spinal muscular atrophy.[1][2][3]

Symptoms include delayed walking, waddling gait, difficulty walking, foot deformities, and loss of some reflexes. Joint contractures are reported frequently, and a few patients present with congenital hip dysplasia.[1] Other symptoms that have being described are an exaggerated curvature of the lower back (hyperlordosis), increased or decreased muscle tone, small chin (micrognathia), respiratory insufficiency, small head (microcephaly), and extra ridges or folds in the brain surface (polymicrogyria).[3] Sensation and cognitive function are normal in most cases.[1][2] Many patients show evident atrophy of the lower limbs and a very broad upper body, which resembles a bodybuilder-like shape.[2] The disease has very slow progression throughout life. It is caused by mutations in the BICD2 gene. Inheritance is autosomal dominant.[1][4] There is no cure and treatment is directed to the symptoms present in each individual patient.

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
5%-29% of people have these symptoms
Fasciculations
Muscle twitch
0002380
Hip contracture
0003273
Hip dysplasia
0001385
Hyperlordosis
Prominent swayback
0003307
Hyperreflexia
Increased reflexes
0001347
Knee flexion contracture
0006380
Scapular winging
Winged shoulder blade
0003691
Spasticity
Involuntary muscle stiffness, contraction, or spasm
0001257
Percent of people who have these symptoms is not available through HPO
Achilles tendon contracture
Shortening of the achilles tendon
Tight achilles tendon

[ more ]

0001771
Areflexia
Absent tendon reflexes
0001284
Autosomal dominant inheritance
0000006
Axial muscle weakness
0003327
Difficulty running
0009046
Gowers sign
0003391
Hyporeflexia
Decreased reflex response
Decreased reflexes

[ more ]

0001265
Motor delay
0001270
Spinal muscular atrophy
Spinal muscle degeneration
Spinal muscle wasting

[ more ]

0007269
Talipes equinovarus
Club feet
Club foot
Clubfeet
Clubfoot

[ more ]

0001762
Toe walking
Toe-walking
0040083
Variable expressivity
0003828
Waddling gait
'Waddling' gait
Waddling walk

[ more ]

0002515

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.

In-Depth Information

  • 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. 
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Autosomal dominant spinal muscular atrophy, lower extremity-predominant 2. Click on the link to view a sample search on this topic.

References

  1. Rudnik-Schöneborn S & cols. Autosomal dominant spinal muscular atrophy with lower extremity predominance: A recognizable phenotype of BICD2 mutations. Muscle Nerve. September, 2016; 54(3):496-500. https://www.ncbi.nlm.nih.gov/pubmed/26998597.
  2. Martinez-Carrera LA & Wirth B. Dominant spinal muscular atrophy is caused by mutations in BICD2, an important golgin protein. Front Neurosci. November 5, 2015; 9:401. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4633519/.
  3. Ravenscroft G & cols. Recurrent de novo BICD2 mutation associated with arthrogryposis multiplex congenita and bilateral perisylvian polymicrogyria. Neuromuscul Disord. November, 2016; 26(11):744-748. https://www.ncbi.nlm.nih.gov/pubmed/27751653.
  4. Spinal muscular atrophy, lower extremity-predominant, 2, AD. OMIM. 2013; https://omim.org/entry/615290.