Life expectancy and death from cardiomyopathy amongst carriers of Duchenne and Becker muscular dystrophy in Scotland

Objectives: To assess life expectancy and cardiovascular mortality in carriers of Duchenne and Becker muscular dystrophy.

Design: Family pedigrees of individuals affected with these conditions, held by the four genetics centres in Scotland, were examined to identify a cohort of definite carriers. Electronic death registration data, held by the General Register Office for Scotland, were used to identify death certificates of carriers who had died, to obtain age at death and cause of death. Survival and mortality data were obtained for the general population for comparison.

Patients: 397 definite carriers in 202 pedigrees were identified from which 94 deaths were identified by record linkage to death certificates.

Main outcome measures: Observed numbers surviving to certain ages and numbers dying of cardiac causes were compared with expected numbers calculated from general population data.

Results: There were no significant differences between observed and expected numbers surviving to ages 40-90. The standardised mortality ratio for the 371 carriers alive in 1974 was 0.53 (95% confidence interval 0.32 to 0.82).

Conclusions: Whereas female carriers may have clinical features of cardiomyopathy, this study does not suggest that this is associated with reduced life expectancy or increased risk of cardiac death. Routine cardiac surveillance of obligate carriers is therefore probably unnecessary.