This invention relates to therapies for diseases involving splicing defects, such as spinal muscular atrophy (SMA), and methods to identify compounds for treating this disease. The invention specifically provides for therapies comprised of small molecule compounds identified by cell-based high-throughput screening assays. These assays utilize engineered splicing constructs that fuse pre-mRNA fragments to a reporter gene. The fragments contain exons and at least one intron of a gene mutated in such a way to cause disease. Additionally, the invention provides for methods to monitor the effects of drugs on splicing and gene expression in vivo, in transgenic animals.