A group of diseases that can begin in infancy or childhood and are characterized by skeletal muscle atrophy caused by progressive degeneration of the anterior horn cells of the spinal cord and motor nuclei in the brainstem. Most cases are autosomal recessive and appear to be allelic mutations at a single locus on chromosome 5. There are four main variants. Type I spinal muscular dystrophy (Werdnig-Hoffmann disease): symptoms are present in the fetus or appear 2 to 4 months after birth. Most infants with the disease show hypotonia at birth; by 6 months of age, all infants with the disease show a significant delay in motor function development. 95% of the children die around 1 year of age, and no case survives beyond 4 years of age, usually from respiratory failure. Type II (intermediate) spinal muscular atrophy: Most children present between 6 and 12 months of age, with all cases having significant symptoms by 2 years of age. Less than 25% of cases learn to sit, but none can walk or crawl. All children show hypotonia with flaccid muscle weakness, loss of tendon reflexes and muscle fasciculations, the latter of which is not readily apparent in young children. Swallowing difficulties may be present. The child often dies at an early age due to respiratory complications, but there are cases of spontaneous arrest of the disease, leaving the child in a permanent non-progressive state of weakness. Type III spinal muscular atrophy/(Wohlfart-Kugelberg-Welander disease)? Onset between 2 and 30 years of age. The pathological changes and genetic pattern are similar to the first two variants, but the disease progresses more slowly and life expectancy is longer. The weakness and muscle atrophy in the legs are most pronounced, with the quadriceps and hip flexors being the first to show symptoms. Later, the arms may be involved. Weakness tends to extend from proximal to distal. Some familial cases may be secondary to specific enzyme deficiencies (e.g., aminohexosidase deficiency). Type IV spinal muscular dystrophy: variable mode of inheritance (autosomal recessive, autosomal dominant, sex-linked), onset in adulthood (age 30-60 years), slow progression of disease. It may not be possible to distinguish it from the lower motor neuron type of amyotrophic lateral sclerosis. Diagnosis and treatment: The clinical diagnosis is usually confirmed if there is loss of innervation on electromyography and if the nerve conduction velocity is normal indicating that the loss of innervation is not caused by peripheral neuropathy. Occasionally, a muscle biopsy is required. Serum enzymes (creatine kinase, aldolase) may be slightly elevated. Amniocentesis does not provide a prenatal diagnosis. There is no specific treatment for this type of disease. In resting or slowly progressing cases, physiotherapy, braces and special orthopedic devices can play a significant role in preventing scoliosis and joint contracture. In addition, vitamin E2 deficiency can also cause symptoms such as muscle atrophy (not only muscle atrophy), and it is advisable to consume animal meat, eggs, milk, dairy products, peanut oil, sesame oil, corn oil, and other foods.