Szabo SM, Gooch KL, Mickle AT, et al. - This study indicates major differences in the natural history of Duchenne muscular dystrophy (DMD) therefore understanding the distribution of pathogenic variants is important for studies in DMD. Additionally, reporting specific details of the use of key medications, including corticosteroids, antisense oligonucleotides, and cardiac medications, is recommended.

• This review was conducted to synthesize published data on the clinical course of DMD by genotype.

• Medline and Embase were systematically searched to identify 53 relevant articles.

• Outcomes reported included those associated with ambulatory, cardiac, pulmonary, or cognitive function.

• Findings revealed that estimates of the mean (95% confidence interval) age at loss of ambulation ranged from 9.1 (8.7-9.6) years in 90 patients amenable to skipping exon 53 to 11.5 (9.5-13.5) years in three patients amenable to skipping exon 8.

• Worsening of function with age was seen but the effect of genotype was less clear for other results (eg, forced vital capacity and left ventricular ejection fraction).