Duchenne muscular dystrophy is typically diagnosed between 4-5 years. A small percentage of boys are diagnosed in infancy, typically because of family history or incidental findings. Limited data is available on these early diagnosed (ED) boys.
Methods: We compared age at diagnosis to corticosteroid use, therapy services, and family history in boys with Duchenne from The Duchenne Registry (TDR)(N=1632) and the United Dystrophinopathy Project (UDP) (N=599). The Early Diagnosed (ED) cohort was defined as diagnosis before birth or <1 year (TDR-ED N=131; UDP-ED N=92). The Average Diagnosed (AD) was defined as diagnosis at age 4 or 5 (TDR-AD N=391; UDP-AD N=124).
Results: Compared to the AD groups, TDR-ED and UDP-ED cohorts were younger at last encounter, and a larger portion had a family history. Corticosteroid initiation was younger in TDR-ED than in TDR-AD (4.2 vs 5.2). When birth cohort was considered, this became more striking: TDR-ED born >=2010 (N=16) had a mean steroid initiation of 3.2, as opposed to 4.9 years in TDR-AD born >=2010 (N=71) (p=0.0009). Mean age of first therapy service in TDR-ED was 1.8 years (N=7), as compared to 4 years in TDR-AD (N=17) (p=0.037). All TDR-ED who received therapy had initiated therapy services <= 4, as opposed to 53% TDR-AD initiating therapies <=4. In both TDR groups, 100% reported seeing benefit from >=1 therapy, with 71% TDR-ED reporting receiving a diagnosis helped access therapies.
Discussion: TDR-ED boys are more likely to start corticosteroids at a younger age, especially those born more recently. In addition, TDR-ED boys who enroll in therapies are more likely to do so at a young age. Given the benefits of corticosteroids prior to the plateau and of early intervention services, early diagnosis can provide significant advantages to boys with Duchenne.