Progressive Duchenne/Becker muscular dystrophy, preclinical stage, deletion of exons 45-55 of the DMD gene in the hemizygous state: a clinical case from practice

Background. Duchenne/Becker progressive muscular dystrophy is an X-linked recessive disease caused by mutations in the DMD gene encoding the dystrophin protein. Deletions of exons 45-55 often correspond to the principle of preserving the reading frame, being associated with the Duchenne/Becker muscular dystrophy phenotype.

Objective. To present a clinical case of the presymptomatic diagnosis of progressive Duchenne/Becker muscular dystrophy in an early-age patient with deletion of exons 45-55 of the DMD gene, analyze diagnostic markers and justify a strategy for dynamic follow-up.

Materials and methods. A retrospective analysis of medical documentation with clinical, laboratory and instrumental methods was performed. In order to form a theoretical base, data was searched and systematized from scientific electronic libraries (CyberLeninka, eLibrary, PubMed, Google Academy) on progressive Duchenne/Becker muscular dystrophy (preclinical phase) and deletion of exons 45-55 of the DMD gene. The review includes literature reviews, scientific publications, and the results of clinical trials on the topic.

Conclusion. A clinical case of diagnosis of progressive Duchenne/Becker muscular dystrophy in a 1-year-old male patient with isolated hyperfermentemia (ALT – 120 U/l, AST – 107.1 U/L) and a significant increase in creatine phosphokinase (4817.1 U/L) is described. Conducted: biochemical examination (creatine phosphokinase, lactate dehydrogenase, creatine phosphokinase-MV), instrumental diagnostics, including electrocardiography, ultrasound examination of the heart and abdominal cavity), molecular genetic analysis. The molecular genetic analysis method verified the hemizygous deletion of exons 45-55 of the DMD gene. The diagnosis of progressive Duchenne/Becker muscular dystrophy was established at the preclinical stage, despite the absence of manifest neurological symptoms. The case demonstrates the critical role of determining of creatine phosphokinase as a screening marker and the need for an integrated approach for early diagnosis. The detection of in-frame deletion creates prerequisites for the potential use of exon-skipping therapy.

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