What is Spinal Muscular Atrophy?

Spinal muscular atrophy (SMA) is a genetic disorder that affects the control of muscle movement. It is caused by a loss of specialized nerve cells, called motor neurons, in the spinal cord and the part of the brain that is connected to the spinal cord. It leads to weakness and wasting (atrophy) of muscles. In severe cases of spinal muscular atrophy, the muscles used for breathing and swallowing are affected. There are many types of spinal muscular atrophy distinguished by the pattern of features, severity of muscle weakness, and age when the muscle problems begin. Spinal muscular atrophy affects one in 6,000 to one in 10,000 people.

How is Spinal Muscular Atrophy Diagnosed?

The first steps in diagnosis of a neuromuscular disease are usually an in-office physical examination and family history, with some simple tests to distinguish spinal muscular atrophy (SMA) from similar conditions, such as muscular dystrophy. Genetic testing will be recommended if SMA is suspected, because this is the least invasive and most accurate way to diagnose. In rare cases, doctors may order a muscle biopsy.

Address/Phone/Email

Address: 401 York Avenue, Duryea, PA 18642 Phone: 1-833-745-3835 Email: info@quantumrehab.com Privacy Policy

How is Spinal Muscular Atrophy Inherited?

Types I, II, III, and IV spinal muscular atrophy are inherited in an autosomal recessive pattern, which means the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. SMA-LED and the adult-onset form of spinal muscular atrophy caused by gene mutations are inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. X-linked spinal muscular atrophy is inherited in an X-linked pattern. The UBA1 gene is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

Types of Spinal Muscular Atrophy

Type I – Called Werdnig-Hoffman disease, is a severe form of the disorder that is evident at birth or within the first few months of life. Affected infants are developmentally delayed, unable to support their head, with breathing and swallowing problems that may lead to choking or gagging.

Type II – Characterized by muscle weakness that develops in children between ages 6 and 12 months. Children can sit without support, but cannot stand or walk unaided.

Type III – Called Kugelberg-Welander disease, has milder features that typically develop between early childhood and adolescence. Individuals can stand and walk unaided, but walking and climbing stairs may become increasingly difficult, many requiring a wheelchair later in life.

Type IV – Often occurs after age 30. Affected individuals usually experience mild to moderate muscle weakness, tremor, twitching, or mild breathing problems. Typically, only muscles close to the center of the body, such as the upper arms and legs, are affected.

X-Linked – Appears in infancy and includes severe muscle weakness and difficulty breathing. Children with this type often have joint deformities that impair movement. In severe cases, affected infants are born with broken bones. Poor muscle tone before birth may contribute to the contractures and broken bones seen in these children.

SMA-LED – Characterized by leg muscle weakness that is most severe in the thigh muscles. This weakness begins in infancy or early childhood and progresses slowly. Affected individuals often have a waddling or unsteady walk and have difficulty rising from a seated position and climbing stairs.

Adult-Onset - Begins in early to mid-adulthood, characterized by muscle cramping of the limbs and abdomen, weakness in the leg muscles, involuntary muscle contractions, tremors, and a protrusion of the abdomen thought to be related to muscle weakness. Some affected individuals experience difficulty swallowing and problems with bladder and bowel function.

Prognosis for Spinal Muscular Atrophy

Recently, survival has increased in severe spinal muscular atrophy patients with aggressive and proactive supportive respiratory and nutritional support. With proper care, milder spinal muscular atrophy type I cases (which account for approx. 10 percent of all SMA1 cases) live into adulthood. In spinal muscular atrophy type II, the course of the disease is slower to progress and life expectancy is less than the general population. Death before the age of 20 is frequent, although many people with spinal muscular atrophy live to become parents and grandparents. Spinal muscular atrophy type III has normal or near-normal life expectancy if standards of care are followed. Type IV, adult-onset spinal muscular atrophy usually means only mobility impairment and does not affect life expectancy.

Power Wheelchair and Seating Solutions for Spinal Muscular Atrophy

For children and adults living with spinal muscular atrophy (SMA), preserving energy, comfort, and independent mobility can become increasingly important as muscle weakness and reduced endurance affect daily activities over time. Quantum Rehab® continues to lead the nation in complex rehab power mobility by creating highly advanced power wheelchair solutions designed to adapt alongside the evolving needs of individuals living with SMA. Known for combining clinical expertise with innovative technology, Quantum® power wheelchairs provide personalized seating, positioning, and drive control solutions that help with independent mobility, energy conservation, posture, and access for both children and adults. Users can maintain greater independence, accessibility, and engagement at home, school, work, and in the community.

TRU-Balance® 4 Power Positioning Systems can support SMA-related needs for posture, pressure redistribution, fatigue reduction, circulation, respiratory comfort, and functional reach. Power tilt, anterior tilt, recline, elevating leg rests, adjustable seat elevation, and programmable memory seating may help users reposition more independently, conserve energy, and maintain comfort throughout the day while accommodating growth or changing strength.

Quantum Q-Logic 3 electronics can be matched to very small or low-force movements. Low-resistance joysticks, switches, head arrays, alternative access methods, Bluetooth®, environmental controls, and iLevel® technology can help users operate the wheelchair and compatible devices with less effort.

SMA mobility support is about development, participation, comfort, and preserving access as strength changes.With intelligent seating technology, personalized mobility solutions, and industry-leading innovation, Quantum power wheelchairs are designed to help individuals living with spinal muscular atrophy experience greater comfort, confidence, mobility, and independence throughout every stage of life.

Please click here for more information on Quantum Power Chair solutions for those living with spinal muscular atrophy.

The Bluetooth® word mark and logos are registered trademarks owned by Bluetooth SIG, Inc. and any use of such marks by Quantum Rehab is under license. Other trademarks and trade names are those of their respective owners.