Key result
Identical Duchenne or Becker mutations linked to ~43% pulmonary function discordance among brothers.
Observational
No
Cardiac and pulmonary function variability is common among brothers with Duchenne or Becker muscular dystrophy despite identical genetic mutations, suggesting genetic testing may not reliably predict cardiopulmonary course.
Variability cautions against relying solely on genotype for DMD/BMD prognosis; leaves open identification of modifying factors.
The Duchenne and Becker forms of muscular dystrophy are associated with dilated cardiomyopathy and are diseases in which pulmonary function peaks and then progressively declines. In this report, the authors quantify cardiopulmonary function variability among brothers. Brothers in 3 of 7 eligible sibships had discordant pulmonary function, with significant differences between the brothers' peak forced vital capacities and their vital capacities at last comparable age. There was no relationship between pulmonary and cardiac function among the siblings. The authors concluded that despite identical genetic mutations, cardiac and pulmonary function variability was common among brothers in their clinic with Duchenne or Becker muscular dystrophy. If confirmed by larger studies, these results have negative implications for the use of genetic testing to predict cardiopulmonary course and response to therapies in Duchenne or Becker muscular dystrophy.
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Birnkrant et al. (2010) conducted an observational in Duchenne or Becker muscular dystrophy. Sibship (identical genetic mutations) vs. Between brothers was evaluated on Discordant pulmonary function. Despite identical genetic mutations, cardiac and pulmonary function variability was common among brothers with Duchenne or Becker muscular dystrophy, with 3 of 7 sibships showing discordant pulmonary function.
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