National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Autosomal dominant spinal muscular atrophy, lower extremity-predominant 2


Other Names:
Autosomal dominant childhood-onset proximal spinal muscular atrophy with contractures; Lower extremity-predominant autosomal dominant proximal spinal muscular atrophy with contractures; SMALED2; Autosomal dominant childhood-onset proximal spinal muscular atrophy with contractures; Lower extremity-predominant autosomal dominant proximal spinal muscular atrophy with contractures; SMALED2; Spinal muscular atrophy, lower extremity-predominant 2, autosomal dominant See More
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.
Last updated: 2/17/2017

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.

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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
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Last updated: 7/1/2020

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

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.

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  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; http://omim.org/entry/615290.