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 2
SMA type 2 is also called “intermediate SMA,” or “chronic infantile SMA.”
Symptoms usually appear between 7 and 18 months of age.2 Parents will likely notice that milestones such as sitting are delayed. Eventually, some of these children will be able to sit without support, but many will not. Symptoms for SMA type 2 vary among patients, but generally include muscle weakness and poor muscle tone, with the legs being weaker than the arms. Some children may experience difficulty in swallowing, and an increased susceptibility to respiratory tract infections. Scoliosis (curvature of the spine) and deformities of the hands, feet, and chest may also develop.3 Approximately 70% of the children with SMA type 2 do not have deep tendon reflexes,1 affecting joints and reducing movement of the limbs, and many have tremors affecting the fingers.
Some children are able to crawl or stand with assistance or bracing, but most likely will never be able to walk.
Severity and prognosis depends on the age of diagnosis, and while some people with SMA type 2 succumb to the disease prematurely, many (especially those diagnosed after 18 months old) may live full and productive lives.
Children with SMA type 2 are bright and alert, and it is important they receive all the opportunities to develop their capacities to the fullest.
Physical activity is highly recommended for children with SMA Type 2, in order to maintain general physical and psychological health and well-being. Hydrotherapy may also be beneficial.3
Follow the latest developments for all experimental Spinal Muscular Atrophy treatments on the SMA Therapy Tracker.
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