Is a muscle biopsy in Duchenne dystrophy really necessary?

The advances in genetics have improved considerably our abilities to diagnose genetic diseases, and these advances are influencing our diagnostic approach to neuromuscular disorders. In spinal muscular atrophy, a rapid gene test identifies 98% of affected cases and therefore a diagnostic muscle biopsy is not needed anymore. Things are more complex regarding Duchenne dystrophy (DD). The gene is very large (at least 85 exons), and genetic studies using widely available techniques can identify mutations in only 60 to 70% of children.1,2⇓ These are frequently deletions (∼60%) and, more rarely, duplications (∼10%). Their detection is facilitated by two mutational hot spots, allowing a multiplex PCR test, based on 19 exons, to identify the great majority (98%) of deletions/duplications.1,2⇓ Southern blot analysis can identify further unusual deletions, whereas the remaining cases are thought to be due to a combination of small mutations (including point mutations) and intronic rearrangements. Specialized techniques such as the protein truncation test can …