Duchenne Muscular Dystrophy Under Three Years of Age

Background/Objectives: Duchenne muscular dystrophy (DMD) is a progressive X-linked neuromuscular disorder. This retrospective study evaluated the demographic, genetic, and clinical characteristics of children diagnosed with DMD before age three to understand early clinical presentation profiles. Methods: The cohort included 198 boys diagnosed with DMD before three years of age between January 2020 and July 2025. Medical records, serum creatine kinase (CK) levels, language milestones via Denver II criteria, and multi-exon deletion maps were retrospectively evaluated. Results: Regarding the diagnostic entry pathways, the initial clinical trigger that led to medical investigation was incidental hyperCKemia in 91.4% of cases. Regardless of the presentation trigger, a definitive, confirmed diagnosis was established in all 198 cases: 196 patients (99.0%) were securely confirmed via genetic testing (MLPA or sequencing), while 2 patients (1.0%) with negative genetic panels were confirmed via muscle biopsy demonstrating a complete absence of dystrophin expression. Genetic analysis revealed deletions in 77.8% of patients, predominantly multi-exon deletions clustered in the distal hotspot region. Independent ambulation occurred at a median age of 16 months, and 14.6% achieved walking after 18 months. Delayed language development was observed in 29.8% of patients. Conclusions: Our findings indicate that early childhood DMD is characterized not only by early muscle involvement but also by prominent neurodevelopmental features. These findings underscore the value of early CK screening in young boys and support integrating standardized neurodevelopmental surveillance into early DMD care.