Werdnig-Hoffman disease (spinal muscular atrophy type 1 or SMA-1): one of the types of spinal muscular atrophy (SMA) diseases. SMAs are a group of inherited diseases that are characterized by progressive weakness of the muscles and reduced muscle tone. The symptoms occur due to loss of motor neurons (nerve cells) in the spinal cord. Werdnig-Hoffman disease is known as SMA-1, SMA type 1, or acute infantile spinal muscular atrophy. Symptoms appear shortly after birth, with 95% of affected individuals showing symptoms prior to 3 months of age. Symptoms include severe, progressive muscle weakness, reduced muscle tone (hypotonia), problems with swallowing and sucking, and respiratory failure. The brain is not involved, and the affected infants are alert. The condition is inherited in an autosomal recessive manner, with the involved gene defects localized on chromosome 5q11.2-13.3. Formerly, children with SMA-1 did not survive more than two years, but with assisted breathing and feeding, many are able to survive longer.
Tsao, Bryan. "Spinal Muscular Atrophy." Medscape.com. May 8, 2013. <http://emedicine.medscape.com/article/1181436-overview>.