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Disease Profile
Spinal muscular atrophy type 2
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.
1-9 / 100 000
Age of onset
Infancy
ICD-10
G12.1
Inheritance
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.
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.
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.
X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.
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
Other names (AKA)
SMA2; Muscular atrophy, spinal, intermediate type; Muscular atrophy, spinal, infantile chronic form;
Categories
Congenital and Genetic Diseases; Nervous System Diseases
Summary
Spinal muscular atrophy type 2 (SMA2) is a genetic
Diagnosis of SMA2 is suspected by symptoms and confirmed by
Symptoms
For information about the signs and symptoms of spinal muscular atrophy in general, click here.
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
|
---|---|---|
Percent of people who have these symptoms is not available through HPO | ||
0000007 | ||
Degeneration of anterior horn |
0002398 | |
EMG abnormality | 0003457 | |
Hand tremor |
Tremor of hand
Tremor of hands
tremors in hands
[ more ] |
0002378 |
Muscle weakness |
Muscular weakness
|
0001324 |
Recurrent respiratory infections |
Frequent respiratory infections
Multiple respiratory infections
respiratory infections, recurrent
Susceptibility to respiratory infections
[ more ] |
0002205 |
Spinal muscular atrophy |
Spinal muscle degeneration
Spinal muscle wasting
[ more ] |
0007269 |
Tongue fasciculations |
Tongue twitching
Twitching of the tongue
[ more ] |
0001308 |
Cause
The protein made by additional copies of SMN2 can compensate for some of the protein lost due to mutations in SMN1. Affected people who have extra copies of SMN2 may, therefore, have milder symptoms and develop the condition later in life.[2]
Diagnosis
Classifying the type of SMA is based on the age of onset and the maximum function attained. Classisfying SMA as type 2 is based on:
- onset of muscle weakness usually after age six months; ability to sit independently achieved when placed in a sitting position
- finger trembling almost invariably present
- low muscle tone (flaccidity)
- absence of tendon reflexes in approximately 70% of individuals
- average intellectual skills during the formative years and above average by adolescence
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
Depending on timing and response to treatment, supportive treatment may include
FDA-Approved Treatments
The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.
- Risdiplam(Brand name: Evrysdi) Manufactured by Genentech
FDA-approved indication: August 2020, risdiplam (Evrysdi) was approved for the treatment of spinal muscular atrophy (SMA) in patients 2 months of age and older.
National Library of Medicine Drug Information Portal - Nusinersen(Brand name: Spinraza) Manufactured by Biogen, Inc
FDA-approved indication: December 2016, nusinersen (Spinraza) was approved for the treatment of spinal muscular atrophy in pediatric and adult patients.
National Library of Medicine Drug Information Portal
Medline Plus Health Information - Onasemnogene abeparvovec(Brand name: Zolgensma) Manufactured by AveXis, Inc.
FDA-approved indication: May 2019, onasemnogene abeparvovec (Zolgensma) was approved for the treatment of pediatric patients less than 2 years of age with spinal muscular atrophy (SMA) with bi-allelicmutations in the survival motor neuron 1 (SMN1) gene.
National Library of Medicine Drug Information Portal
Related diseases
Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.
Conditions with similar signs and symptoms from Orphanet
|
---|
Differential diagnoses include amyotrophic lateral sclerosis, congenital muscular dystrophies, congenital myopathies, primary lateral sclerosis, myasthenia gravis, and carbohydrate metabolism disorders (see these terms).
Visit the Orphanet disease page for more information.
|
Organizations
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
-
Cure SMA
925 Busse Road
Elk Grove, IL 60007
Toll-free: 800-886-1762
Telephone: 847-367-7620
Fax: 847-367-7623
E-mail: [email protected]
Website: https://www.curesma.org -
SMA Europe
Europe,
Telephone: +44 (0)1789 801159
E-mail: [email protected]
Website: https://www.sma-europe.eu/ -
Spinal Muscular Atrophy Association of Australia Inc. (SMA Australia)
PO Box 5245 (mail)
Unit 7 16-28 Melverton Drive (office)
Hallam Vic, 3803 Australia
Telephone: (03) 9796 5744
Fax: 03 83737 7787
E-mail: [email protected]
Website: https://smaaustralia.org.au/ -
Spinal Muscular Atrophy Foundation
888 Seventh Avenue
Suite 400
New York, NY 10019
Toll-free: 877-FUND-SMA (877-386-3762)
Telephone: 646-253-7100
Fax: 212-247-3079
E-mail: [email protected]
Website: https://www.smafoundation.org
Organizations Providing General Support
-
Muscular Dystrophy Association (MDA)
222 S Riverside Plaza
Suite 1500
Chicago, IL 60606
Toll-free: 1-833-275-6321 (Helpline)
E-mail: [email protected]
Website: https://www.mda.org
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
- Families of SMA has created a booklet entitled Understanding SMA that is intended to serve as a source of information and support for children and adults with Spinal Muscular Atrophy (SMA).
- MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
- Genetics Home Reference (GHR) contains information on Spinal muscular atrophy type 2. This website is maintained by the National Library of Medicine.
- The National Institute of Neurological Disorders and Stroke (NINDS) collects and disseminates research information related to neurological disorders. Click on the link to view information on this topic.
- The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.
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.
- Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
- 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.
- 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 Spinal muscular atrophy type 2. Click on the link to view a sample search on this topic.
References
- Prior TW, Finanger. Spinal Muscular Atrophy. GeneReviews. December 22, 2016; https://www.ncbi.nlm.nih.gov/books/NBK1352/.
- Spinal Muscular Atrophy. Genetics Home Reference. January 2013; https://ghr.nlm.nih.gov/condition/spinal-muscular-atrophy.
- Kariyawasam D, Carey KA, Jones KJ, Farrar MA. New and developing therapies in spinal muscular atrophy. Paediatr Respir Rev. April 5, 2018; pii: S1526-0542(18):30048-4. https://www.ncbi.nlm.nih.gov/pubmed/29703692.
- Claborn MK, Stevens DL, Walker CK, Gildon BL. Nusinersen: A Treatment for Spinal Muscular Atrophy. Ann Pharmacother. July 1, 2018; 1060028018789956. https://www.ncbi.nlm.nih.gov/pubmed/30008228.
- Mercuri E, Finkel RS, Muntoni F, et al. Diagnosis and management of spinal muscular atrophy: Part 1: Recommendations for diagnosis, rehabilitation, orthopedic and nutritional care. Neuromuscul Disord. February 2018; 28(2):103-115. https://www.sciencedirect.com/science/article/pii/S0960896617312841?via%3Dihub.
- Finkel RS, Mercuri E, Meyer OH, et al. Diagnosis and management of spinal muscular atrophy: Part 2: Pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics. Neuromuscul Disord. March 2018; 28(3):197-207. https://www.sciencedirect.com/science/article/pii/S0960896617312907?via%3Dihub.
- Thomas W Prior, PhD, FACMG and Barry S Russman, MD. Spinal Muscular Atrophy. GeneReviews. November 2013; https://www.ncbi.nlm.nih.gov/books/NBK1352/.
- Bryan Tsao. Spinal Muscular Atrophy. Medscape Reference. 2015; https://emedicine.medscape.com/article/1181436-overview.
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