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Spinal muscular atrophy (SMA), a disease with a global incidence of 1 in 10,000 and a prevalence of 1 in 6,000 in Turkey, has four types. SMA types are classified based on the age of onset. Types 1 and 2 are the most common.
Type 1 (severe) SMA: Also known as Werdnig-Hoffmann disease, this is the most severe and common type. It typically appears in infants aged 0-6 months, often at birth or within the first few months. Symptoms include floppiness in the legs and weak trunk movement. Individuals with Type 1 SMA have very limited mobility; infants cannot sit. They also experience difficulty feeding, swallowing, holding their head up, and breathing. Type 1 SMA progresses rapidly, leading to muscle weakness and respiratory infections.
Type 2 (intermediate) SMA: Milder than Type 1, symptoms usually appear in infants aged 7-18 months. Children with Type 2 SMA never stand or walk but may crawl; the rate of progression varies greatly. It affects the legs more than the arms. Tremors in the hands, scoliosis, weakness, and failure to thrive may also occur. Respiratory infections are common. Life expectancy ranges from early childhood to adulthood depending on severity.
Type 3 (mild) SMA: Also known as Kugelberg-Welander disease or juvenile spinal muscular atrophy, symptoms begin after 18 months. Children may develop normally until then, with symptoms potentially not appearing until adolescence. Individuals with Type 3 SMA can stand and walk but may have difficulty getting up from a sitting position. They may require a wheelchair for mobility. They are also at risk for respiratory infections.
Type 4 (adult) SMA: This rare type has symptoms that appear in adulthood. Progression is slow. Individuals often reach all developmental milestones and maintain mobility throughout life, with other complications being uncommon.
If you notice any of these symptoms in yourself or your child, consult a doctor immediately.
What are the Types of SMA?
Type 1 (severe) SMA: Also known as Werdnig-Hoffmann disease, this is the most severe and common type. It typically appears in infants aged 0-6 months, often at birth or within the first few months. Symptoms include floppiness in the legs and weak trunk movement. Individuals with Type 1 SMA have very limited mobility; infants cannot sit. They also experience difficulty feeding, swallowing, holding their head up, and breathing. Type 1 SMA progresses rapidly, leading to muscle weakness and respiratory infections.
Type 2 (intermediate) SMA: Milder than Type 1, symptoms usually appear in infants aged 7-18 months. Children with Type 2 SMA never stand or walk but may crawl; the rate of progression varies greatly. It affects the legs more than the arms. Tremors in the hands, scoliosis, weakness, and failure to thrive may also occur. Respiratory infections are common. Life expectancy ranges from early childhood to adulthood depending on severity.
Type 3 (mild) SMA: Also known as Kugelberg-Welander disease or juvenile spinal muscular atrophy, symptoms begin after 18 months. Children may develop normally until then, with symptoms potentially not appearing until adolescence. Individuals with Type 3 SMA can stand and walk but may have difficulty getting up from a sitting position. They may require a wheelchair for mobility. They are also at risk for respiratory infections.
Type 4 (adult) SMA: This rare type has symptoms that appear in adulthood. Progression is slow. Individuals often reach all developmental milestones and maintain mobility throughout life, with other complications being uncommon.
If you notice any of these symptoms in yourself or your child, consult a doctor immediately.