RTC13 is a cell-permeable thiazolidinone derivative that promotes ribosomal read-through activity of premature termination codons (PTCs) and effectively restores full-length protein production from transcripts containing nonsense mutations-generated PTCs, including ataxia-telangiectasia (A-T) mutated in A-T lymphoblastoid cell cultures and dystrophin in mdx Duchenne muscular dystrophy (DMD) mice-derived muscle myotubes.