This lecture covers Spinal Muscular Atrophy (SMA), an autosomal recessive disease caused by mutations in the SMN1 gene, leading to muscle weakness, atrophy, and neurodegeneration. Different disease classes are discussed based on severity, age of onset, and life expectancy. The role of the SMN2 gene in SMA pathogenesis is explained, focusing on exon splicing and protein levels. Gene therapy strategies for SMA are explored, highlighting the importance of SMN2 copy numbers and potential clinical benefits.