a severe neuromuscular
disease characterized by degeneration of alpha motor
neurons in the spinal cord, resulting in progressive
proximal muscle weakness and paralysis. The disease
was first described in the 1890s by Werdnig [1] and by
Hoffmann [2]. The genetic defect was localized to
5q11.2-q13.3 a century later [3] with the identification
of the survival motor neuron gene (SMN) gene as the
disease-causing gene in 1995 [4].