About 1 in 5,000 boys in the United States have Duchenne muscular dystrophy or Becker muscular dystrophy, according to the first broad study of the disorders that weaken muscles and strike mostly males.
The diseases appear to affect Hispanic boys more often than white or African-American boys, although the reasons why are still not well understood.
The findings, published in the journal Pediatrics, are important because they offer a better understanding of the number of children and families affected and provide doctors and health-care professionals with valuable information so they can better care for those affected, especially as the diseases progress, researchers say.
No cure for either disorder
“There were always some rather crude estimates of how common these muscular dystrophies are,” says Paul Romitti, an epidemiologist at the University of Iowa. “It tells us that they’re still an important public health concern.”
Muscular dystrophies are a group of genetic disorders that result in muscle weakness over time. The most common muscular dystrophy in children is Duchenne muscular dystrophy, which predominantly affects boys.
Historically, Duchenne has resulted in loss of walking ability between ages 7 and 13 years, and death in the teens or 20s. Becker muscular dystrophy is similar to Duchenne, but has later onset and slower, more variable progression of symptoms. There is no cure for either disorder.
Hispanic youth most affected
In the population-based study, researchers analyzed data—culled mostly from birth and death certificates and medical records—for children born between 1982 and 2011 in six states: Arizona, Colorado, Georgia, Hawaii, Iowa, and western New York.
Researchers calculated the disorders’ prevalence across four five-year time periods, beginning in the 1991-1995 period and ending in 2006-2010.
The disorders showed up in roughly 2 per 10,000 boys in the 1991-1995, 1996-2000, and 2001-2005 periods. In 2006-2010, the prevalence was 1.5, but the researchers believe the lower figure could be due to delayed diagnosis, among other factors.
Hispanic youth had a higher prevalence in all but the last time period. African-American children were least likely to be affected for all time periods.
Three-quarters of the 845 total cases were Duchenne.
The frequency across the time periods is roughly the same as found in an earlier study that included four states and reported in 2007, and one done in Colorado in 1974.
Despite the conditions’ rarity, medical professionals should be prepared, researchers say.
“People who have these disorders require daily attention from their families and complex care management from health-care providers,” Romitti says.
“The new data will help to estimate the cost for the parents and the health-care system. We are continuing to learn more about the total impact of these disorders on the child and the family.”
Other researchers from the University of Iowa, University of Rochester, University of Arizona, University of Colorado-Aurora, the New York State Department of Health, and the Centers for Disease Control and Prevention contributed to the study.
The US Centers for Disease Control funded the work.
Source: University of Iowa