The symptoms of spinal muscular atrophy vary widely. According to the age of onset and clinical course of the patient, spinal muscular atrophy is divided into four types from severe to mild. Four types can have the following symptoms: 1. Type I is called infantile type, which starts within 6 months after birth and develops rapidly, showing progressive, symmetrical muscle weakness of the limbs and inability to sit alone. Expression muscles and eye movements are mostly normal, tongue muscles can be fibrillated, and oropharyngeal muscles are weak, resulting in a weak cry, weak sucking, and a weakened gag reflex, in addition to aspiration. Infantile respiratory muscle weakness is prominent and most children die of respiratory failure within 2 years of age. 2. However, most children lose the ability to sit alone in childhood and their life expectancy is shortened, but some patients can live into adulthood; 3. Type III, the adolescent type, starts after 18 months of age and has normal motor development and can walk alone in the early stages. However, as the patient grows older, muscle weakness in the extremities may appear and the ability to walk independently may eventually be lost. In addition, it can be accompanied by limb fasciculations, foot deformities, scoliosis and respiratory insufficiency in some patients. Therefore, it can affect daily life and lead to a shortened or mildly decreased life expectancy of the patient. 4. Type IV is a late form, also known as adult type. Patients have relatively normal motor development in early stages, and the disease starts in adulthood. The proximal limb weakness usually appears, and the progression is relatively slow, and life expectancy is not shortened, so the prognosis for this type of patient is better.