Theragnosis for Duchenne Muscular Dystrophy

Area of Science:

• Genetics and Molecular Biology
• Neurology
• Rare Diseases

Background:

• Dystrophinopathies, including Duchenne muscular dystrophy (DMD), are severe X-linked muscle diseases caused by DMD gene mutations.
• While no cure exists, targeted therapies like exon skipping and stop codon read-through offer new treatment avenues.
• Characterizing mutation profiles is crucial for identifying eligible patients for these emerging pharmacogenetic treatments.

Purpose of the Study:

• To determine the mutational spectrum of the DMD gene in an Argentinian cohort.
• To identify patients suitable for existing exon skipping and premature stop codon read-through therapies.
• To compare mutation frequencies amenable to DMD therapies across Latin America.

Main Methods:

• A cohort of 400 patients with diagnosed dystrophinopathy was studied.
• A diagnostic molecular algorithm involving MLPA, PCR, Sanger sequencing, exome sequencing, and bioinformatics was implemented.
• A meta-analysis of Latin American data on DMD therapies was conducted.

Main Results:

• The molecular algorithm achieved a 97% detection rate, enabling accurate diagnosis and corticosteroid treatment for 371 patients.
• Specific patient groups were identified as eligible for exon skipping (exons 51, 53, 45) and stop codon read-through therapies.
• 87.5% of DMD patients could restore the reading frame via single exon skipping; UGA was the most frequent premature stop codon (47%).
• Only four Latin American countries offer comprehensive molecular diagnostics for dystrophinopathies; nonsense variants were consistently around 40% across populations.

Conclusions:

• The implemented molecular algorithm is effective for diagnosing dystrophinopathies, guiding treatment, and facilitating genetic counseling.
• This study provides essential data on mutation frequencies in Latin America, supporting drug development and theranostic strategies.
• Theranostic approaches, combining diagnosis with targeted therapy selection, are vital for managing rare genetic muscle diseases like DMD.