What you need to know about spinal muscular atrophy (SMA)

What is SMA?

SMA is a severe neuromuscular disease caused by a genetic defect in the SMN1 (survival motor neuron 1) gene. It leads to the loss of motor neurons and results in progressive muscle weakness and paralysis.

It's the number 1
genetic cause of infant death

As many as 1 in 10,000
live births will be affected

1 in 50 americans
are genetic carriers

SMA can affect people
of any race or gender

Survivors REQUIRE lifelong
care and support

Be SMA aware

SMA is a rare condition, yet it is the number one genetic cause of infant death. Early diagnosis
is critical in this fast-moving disease.

Signs and Symptoms of SMA
Watch this video to hear parents of children with SMA talk about the early signs and symptoms to look for to help reach a diagnosis quickly.

There are four types of SMA:

Type 1 (also called werdnig-hoffman disease) is the most severe

Early onset with diagnosis usually in an infant's first 6 months

Most severe type with 90% mortality or need for permanent ventilation support by 2 years old

60% of all sma cases are type 1

Type 1 symptoms:

Hypotonia or "floppy baby syndrome" is an abnormal limpness in the neck and limbs
Muscle weakness (particularly in the legs)
Poor head control
Abdominal breathing, also called "diaphragmatic" or "belly breathing," is contraction of the diaphragm rather than the chest, when breathing
Bulbar muscle weakness which is exhibited by a weak cry, difficulty swallowing and aspiration
Inability to sit unsupported

Type 2 (also called Dubowitz Syndrome)

Onset between 6 to 18 months of age
Reduced life expectancy; 68% alive at age 25
Will never be able to walk without support
Most will never stand without support

Type 3 (also called Kugelberg-Welander disease or juvenile SMA)

Onset after 18 months
Can be diagnosed as late as the teenage years
Individuals affected are initially able to walk but have increasingly limited mobility as they grow

Type 4 (Adult Onset)

Very rare
Symptoms can start as early as 18 years but usually begin after age 30
Mobility characteristics are similar to Type 3

Learn more about SMA resources