In this article, the latest news on clinical trials in: weight and nutrition * Heart changes in FSH dystrophy * heart problems in Duchenne MD * siblings' similarities in MMD * myotonia congenita * late-onset Pompe's disease * parents' input
Although it's long been known that some muscular dystrophies, such as Duchenne, Becker and myotonic, almost always affect the heart muscle, it's been thought that others, such as facioscapulohumeral MD (FSHD), spare this important organ.
But recently, researchers at the University of Pisa in Italy have found that at least some people with FSHD have subtle cardiac abnormalities that might set the stage for more serious problems later on.
Fabio Gletta and colleagues, who published their report in the June issue of Neuromuscular Disorders, found that the 24 FSHD-affected participants they studied had more evidence of reduced function in the left ventricle (lower heart chamber) and of abnormal cardiac muscle cell electrical activity than did 24 non-FSHD control subjects.
However, the participants had no symptoms of heart disease, and their problems weren't revealed in traditional EKG testing or echocardiograms. (Special testing was done in this study.)
The investigators believe that additional factors, or triggers, are required for significant cardiac rhythm abnormalities to develop in these subtly affected patients.
They found that those with FSHD had indices of abnormal signal transmission in the muscle layer of the heart. While this subtle type of cardiac abnormality wasn't related to the severity of skeletal muscle function, it was correlated with the size of the FSHD-related genetic defect on chromosome 4.
A technique that can be applied in conjunction with a standard echocardiogram (an ultrasound picture of the heart) can add to the sensitivity of this procedure for people with Duchenne muscular dystrophy (DMD), a study conducted at Baylor College of Medicine and Texas Children's Hospital in Houston found.
The results, announced at a meeting of the American Society of Echocardiography (ASE) in Boston in June, say adding tissue doppler imaging, which measures how fast the heart's walls move, can identify early changes in the heart muscle before serious symptoms of cardiac abnormalities occur.
Schuping Ge, a pediatric cardiologist and the lead author of the study, says in an ASE press release, "We wanted to find a way to detect early, minor changes of the heart muscle in hopes of guiding early therapy that can slow down or reverse those changes."
Cardiologist and MDA grantee Elizabeth McNally at the University of Chicago Hospitals says the study suggests that tissue doppler during echocardiograms is useful to help identify even earlier those boys with DMD at risk of developing cardiomyopathy.
Siblings with type 1 myotonic dystrophy (MMD) are similar to each other in the severity of skeletal muscle weakness and cardiac abnormalities. Those similarities are independent of their closeness in age or the number of CTG repeats in their DNA, the MMD1-causing genetic defect on chromosome 19.
So say the results of a study conducted at Pennsylvania State University in Hershey and Indiana University in Indianapolis and published in the June issue of Muscle & Nerve. The study was in part supported by MDA, and participants were recruited from MDA clinics at Indiana University and Hershey Medical Center.
"The findings suggest that genetic factors other than CTG repeat length, or environmental factors, which may be similar in siblings, modulate both the skeletal and cardiac muscle involvement in DM1 [type 1 MMD]," the authors write. They say the factors responsible for the familial clustering are unknown but may have a significant impact on the overall disease state and clinical outcomes.
The muscle disease myotonia congenita varies greatly in severity, says a Danish study published in the July issue of Muscle & Nerve.
Eskild Colding-Jorgensen of the University of Copenhagen found that disease severity in myotonia congenita can be hard to predict, even if the precise gene flaw (mutation) in the CLCN1 gene has been identified.
It's been known for decades that myotonia congenita can be inherited in either a dominant pattern, in which only one mutated gene is needed to cause symptoms, or a recessive pattern, in which a mutation from each parent is needed to interfere with muscle relaxation.
But it seems there are other factors that influence disease severity. These may include age, which sometimes improves the disease over time; pregnancy, which can worsen the disease; exposure to cold, which can aggravate or improve symptoms; and exercise, which can lessen myotonia in the short run and may even have long-term benefits.
In addition, an incompletely understood genetic mechanism that causes a cell to prefer one of its two inherited genes for a protein may be a factor, Colding-Jorgensen adds. This sometimes results in producing more of the abnormal protein than one would predict.
He also notes that the warm-up effect in myotonia congenita, in which the myotonia disappears after brief exercise, deserves more attention, since it may provide clues for treatment development.
The biopharmaceutical company Genzyme is screening people with late-onset Pompe disease (acid maltase deficiency) for a future trial to evaluate Myozyme, the company's replacement enzyme for acid maltase that's shown promise in babies with the infantile form of the disease.
Genzyme is seeking people with definite or probable Pompe disease who are at least 8 years old and able to walk with or without assistive devices. For this screening, Genzyme is excluding people who have participated in its observational study of late-onset Pompe, as well as those who use tracheostomy ventilation or require noninvasive ventilation while awake and upright.
Genzyme's expanded access program allows some people who don't meet study requirements to receive Myozyme. For details on screening sites, contact Genzyme at (800) 745-4447, or email@example.com.
Muscular Dystrophy Surveillance, Tracking and Research Network (MD STARnet), under the auspices of the U.S. Centers for Disease Control and Prevention (CDC), is actively seeking participants for two studies.
Investigators in the Palliative Care Project want to interview parents of children with Duchenne muscular dystrophy to determine their needs and the services of which they're aware.
Participants must live in Arizona, Colorado, Iowa or Western New York state and be willing to give the researchers an approximately 30-minute telephone interview, for which they will be compensated.
The Assistive Technology Project is for parents of children and young men ages 5 to 21 with Duchenne or Becker muscular dystrophy who live in Arizona.
This study, funded in part by MDA, will assess the use families make of assistive technology and investigate the effects of technology on health and well-being.
Parents, who will receive compensation, will be asked to complete a written questionnaire, and participate in a 10-minute interview at their sons' next clinic visit.