Clinical features of spinal muscular atrophy in children

Spinal muscular atrophy (SMA) is a neurodegenerative disease characterized by a loss of motor neurons in the anterior horn of the spinal cord and by resultant progressive, mainly proximal, weakness. A phenotypic spectrum includes pulmonary, gastrointestinal, nutritional complications, scoliosis and contractures. The most common form of SMA, accounting for 95% of cases, is autosomal recessive proximal SMA associated with mutations in the survival of motor neurons (SMN1) gene. It is a rare disorder with the incidence 1 : 6,000-1 : 10,000. The clinical spectrum ranges from early infant death to normal adult life with only mild weakness. SMA is classified into four types depending on the age of onset and highest level of motor function achieved. Actual treatment and multidisciplinary care change the course of the disease and improve life expectancy and quality of life.