The group of genetic disorders that are lumped together as the muscular dystrophies are reviewed comprehensively this month in Pediatrie Annals. Although many of the conditions discussed are rare, as a group, they are somewhat common afflictions of childhood.
These disorders exemplify very well the amazing advances in molecular medicine during the past decade or two. Many of the key proteins involved in muscle structure and function have been identified, many of the genes that encode these proteins have also been identified and localized to a chromosome, and many of the specific genetic mutations that lead to disease have been discovered.
It is now known that a mutation of the gene on the short arm of the X chromosome that encodes dystrophin is responsible for Duchenne and Becker muscular dystrophy, with resultant impaired contractile function of muscle cells. In addition, there are at least 13 subtypes of limb-girdle muscular dystrophy, with different genetic mutations involving the genes encoding for 13 different proteins. Some of the several varieties of the congenital muscular dystrophies involve abnormalities of the muscle proteins merosin (laminin ct-2), fukutin, and something called FKRP. And there are others as well.
The multisystemic effects of these genetic muscular disorders are highlighted in the reviews of the cardiac features of the muscular dystrophies, the pulmonary complications, and the need for interdisciplinary palliative care for the children (primarily boys) with these progressive neuromuscular impairments. The immediate and the long-term benefits of chronic nocturnal ventilation and of noninvasive intermittent positive pressure ventilation in patients with muscular dystrophy are detailed well by Kalra and Amin, while Markham and colleagues clearly highlight the practical measures that are useful for the diagnosis and treatment of the cardiac features of these myopathies.
The recent 50th anniversary of Jonas Salk's successful testing of his polio vaccine has reminded me of the poliomyelitis patients treated in iron lungs. I am not quite old enough to have cared for polio patients in iron lungs (Dr. Sam Katz recently indicated that 39 polio survivors in the United States still requiring ventilatory support from decades ago remain alive), but I do recall several muscular dystrophy patients several decades ago who were treated in iron lungs that were left over from the polio era.
Believe it or not, there is a muscular dystrophy stamp in my collection of medical stamps. The 2002 Italian stamp shown here highlights a telethon to combat muscular dystrophy and other genetic disorders and depicts a microscope and DNA. The 1992 stamp from Grenada commemorates the World Health Organization theme of that year, cardiac health, which is important to many muscular dystrophy patients. Lastly, the green stamp from Dominica celebrates Joñas Salk's historic development of the killed polio vaccine and its successful implementation, announced at the University of Michigan on April 12, 1955 - 10 years to the day after the death of President Franklin D. Roosevelt, a polio survivor.