A research team led by the University of Iowa has reported the frequency of two muscle-weakness disorders that strike mostly boys- Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy. Researchers found that about 1 in 5,000 boys, between 5 and 9 years old, have the inherited disorders. They also found that the diseases appear to affect Hispanic boys more often than white or African-American boys, for reasons that are not well understood.
The findings of the study are important, because they give a better understanding of the number of children and families affected by the disorders. It also give doctors and health-care professionals valuable information, so they can better plan to care for those affected, especially as the diseases progress. Author of the study, Paul Romitti, said, "There were always some rather crude estimates of how common these muscular dystrophies are. It tells us that they're still an important public health concern."
Muscular dystrophies are a group of genetic disorders that eventually result in muscle weakness over time. The most common muscular dystrophy in children is DMD, which predominantly affects males. DMD 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 DMD, but has later onset and slower, more variable progression of symptoms. There is no cure for either muscular dystropy.
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. They calculated the prevalence of the disorders' across 4-5 year time periods, beginning in the 1991-1995 period and ending in 2006-2010. The research team found the disorders in roughly 2 per 10,000 boys in the 1991-1995, 1996-2000 and 2001-2005 periods. But, in 2006-2010, the prevalence was 1.5. The researchers believe the lower figure could be due to delayed diagnosis, among other factors. Hispanic youth had a higher prevalence of the disorder in all but the last time period, while African-American children were least likely to be affected for all time periods. The study revealed that three-quarters of the 845 total cases were Duchenne.
Romitti said, "People who have these disorders require daily attention from their families and complex-care management from health-care providers. 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."
The study appears online in the journal 'Pediatrics'.