Dystrophin Exon 29 Nonsense Mutations Cause a Variably Mild Phenotype.

Background: Nonsense mutations in the dystrophin gene usually result in a severe Duchenne muscular dystrophy phenotype. Findings: We describe a 7-year-old boy with a rare pathogenic mutation in exon 29 c.3940C>T p.(Arg1314Ter) resulting in exon skipping, in turn rescuing the phenotype from a severe Duchenne type to a milder Becker muscular dystrophy type. No adults have been described with this mutation to date. Conclusions: Exon skipping of exon 29 results in a higher level of functional dystrophin. Some cases of muscular dystrophy may still require muscle biopsy to determine optimal management and pharmaceutical treatment options.