Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Brain & Nervous System Health Center

Font Size

Spinal Muscular Atrophy

It is possible that the main title of the report Spinal Muscular Atrophy is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • SMA

Disorder Subdivisions

  • SMA type 0
  • SMA type 1
  • SMA type 2
  • SMA type 3
  • SMA type 4

General Discussion

Spinal muscular atrophy (SMA) is a group of inherited disorders characterized by a loss of certain nerve cells in the spinal cord called motor neurons or anterior horn cells. Motor neurons receive the nerve impulses transmitted from the brain to the spinal cord (brainstem) and, in turn, transmit the impulses to the muscle via the peripheral nerves. The loss of motor neurons leads to progressive muscle weakness and muscle wasting (atrophy) in muscles closest to the trunk of the body (proximal muscles) such as the shoulders, hips and back. These muscles are necessary for crawling, walking, sitting up and head control. The more severe types of SMA can affect muscles involved in feeding, swallowing and breathing.

SMA is divided into subtypes based on age of onset and maximum function achieved. SMA types 0, 1, 2, 3 and 4 are inherited as autosomal recessive genetic disorders and are associated with abnormalities (mutations) in the SMN1 and SMA2 genes which are located on chromosome 5.


March of Dimes Birth Defects Foundation
1275 Mamaroneck Avenue
White Plains, NY 10605
Tel: (914)997-4488
Fax: (914)997-4763
Tel: (888)663-4637

Families of Spinal Muscular Atrophy
925 Busse Road
Elk Grove Village, IL 60007
Tel: (847)367-7620
Tel: (800)886-1762

Muscular Dystrophy Association
3300 East Sunrise Drive
Tucson, AZ 85718-3208
Tel: (520)529-2000
Fax: (520)529-5300
Tel: (800)572-1717

NIH/National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
Tel: (301)496-5751
Fax: (301)402-2186
Tel: (800)352-9424
TDD: (301)468-5981

Jennifer Trust for Spinal Muscular Atrophy
40 Cygnet Court
Timothy's Bridge Road
Stratford upon Avon
Warwickshire, CV37 9NW
United Kingdom
Tel: 4401789267520
Fax: 4401789268371
Tel: 8009753100

New Horizons Un-Limited, Inc.
811 East Wisconsin Ave
P.O. Box 510034
Milwaukee, WI 53203
Tel: (414)299-0124
Fax: (414)347-1977

Genetic and Rare Diseases (GARD) Information Center
PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311
TDD: (888)205-3223

Madisons Foundation
PO Box 241956
Los Angeles, CA 90024
Tel: (310)264-0826
Fax: (310)264-4766

Fight SMA/Spinal Muscular Atrophy
1807 Libbie Avenue
Suite 104
Richmond, VA 23226
Tel: (804)515-0080
Fax: (804)515-0080

Claire Altman Heine Foundation, Inc.
1112 Montana Avenue, #372
Santa Monica, CA 90403
Tel: (310)260-3262
Fax: (310)393-7154

Children with Spinal Muscular Atrophy Ukraine
Gogolia Street 7
Kharkiv, 61057
Tel: 380503640673

Spinal Muscular Atrophy Foundation
888 Seventh Avenue
Suite 400
New York, NY 10019
Tel: (646)253-7100
Fax: (212)247-3079
Tel: (877)386-3762

Child Neurology Foundation
201 Chicago Ave, #200
Minneapolis, MN 55415
Tel: (952)641-6100
Fax: (952)881-6276
Tel: (877)263-5430

For a Complete Report:

This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site or email

Last Updated: 4/10/2012
Copyright 2004, 2005, 2006, 2007, 2008, 2012 National Organization for Rare Disorders, Inc.

WebMD Medical Reference from the National Organization for Rare Disorders

Last Updated: May 28, 2015
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

Today on WebMD

nerve damage
Learn how this disease affects the nervous system.
senior woman with lost expression
Know the early warning signs.
woman in art gallery
Tips to stay smart, sharp, and focused.
medical marijuana plant
What is it used for?
senior man
boy hits soccer ball with head
red and white swirl
marijuana plant
brain illustration stroke
nerve damage
Alzheimers Overview
Graphic of number filled head and dna double helix