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 mutations in the SMN1 gene, which is located on chromosome 5.1

Spinal Muscular Atrophy Type 1

SMA type 1, also called Werdnig-Hoffman disease, is another severe form of SMA. It is the most common type of spinal muscular atrophy.1

Symptoms of SMA type 1 may be present at birth or within the first few months of life. These infants usually have difficulty breathing and swallowing, a weak sucking reflex,2 floppy limbs and trunk, feeble arm and leg movements (poor muscle tone), and impaired breathing. The legs tend to be more impaired than the arms,3 and a twitching of the tongue is often seen. While the body is significantly affected by Spinal Muscular Atrophy type 1, intelligence in these children is normal.1

Children with SMA type 1 likely will only be able sit upright with support.

The rate of progression of SMA type 1 varies. Within a few months, breathing and bowel (constipation) difficulties may develop. Respiratory failure may occur or food inhaled onto the lungs may cause choking.

These children usually survive up to age 2 without respiratory assistance. They can survive longer, however, if given respiratory support.

Read the latest news about SMA type 1 at SMA News Today.

Follow the latest developments for all experimental Spinal Muscular Atrophy treatments on the SMA Therapy Tracker.

SMA News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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  1. http://rarediseases.org/rare-diseases/spinal-muscular-atrophy/
  2. http://www.genome.gov/20519681/learning-about-spinal-muscular-atrophy/