Spinal muscular atrophy (SMA) can be categorized as acute infantile, chronic infantile, juvenile, and adult. They develop at different ages. 1. Acute infantile type develops at 3~6 months of age, manifested by decreased voluntary activity, proximal weakness of limbs, accompanied by muscle atrophy, muscle fiber fibrillation, inability to raise the head and flex the neck, and decreased or absent tendon reflexes. 2. Chronic infantile type usually develops at 6 months after birth, occasionally at 1~2 years old. Early onset of tongue muscle atrophy, fibrillation. 3. The juvenile type usually starts insidiously in childhood or adolescence, manifested by weakness and atrophy of the proximal muscles of the lower limbs, and difficulty in standing and walking up the stairs. 4. Adult type mostly develops at the age of 35-60 years, with clinical manifestations similar to those of the juvenile type, and may also involve the posterior cerebral nerves and facial muscles, resulting in dysarthria, dysphagia, dyspnea, and respiratory difficulties. Currently, there is no effective treatment for spinal muscular atrophy, and symptomatic and supportive treatment is the mainstay. If symptoms occur, it is necessary to consult a doctor as soon as possible, and actively cooperate with the treatment under the guidance of the doctor.