I’ve gotten so many great questions from family and friends about what exactly is Becker’s Muscular Dystrophy and what does that mean for my boys? I wanted to start with posting the medical explanation of Duchenne/Becker Muscular Dystrophy since the names are often used together or interchanged. They are basically the same condition, just on a scale with Duchenne being at the severe, faster progressing end, and Becker’s being at the less severe, slower progressing end. The spectrum is so large though, a child can have a less severe from of Duchenne, or a more severe form of Becker’s, it can vary so much from one child to the next. The doctors are pretty sure my boys have Becker’s, the severity and speed of progression are unsure at this point. We can do muscle biopsies on the boys to get a little clearer picture of the speed of progression, but we don’t feel like we need to do anything invasive as long as the boys are doing well right now.
This is an explanation from ‘Genetics Home Reference’ http://ghr.nlm.nih.gov/condition/duchenne-and-becker-muscular-dystrophy
What is Duchenne and Becker muscular dystrophy?
Muscular dystrophies are a group of genetic conditions characterized by progressive muscle weakness and wasting (atrophy). The Duchenne and Becker types of muscular dystrophy are two related conditions that primarily affect skeletal muscles, which are used for movement, and heart (cardiac) muscle. These forms of muscular dystrophy occur almost exclusively in males.
Duchenne and Becker muscular dystrophies have similar signs and symptoms and are caused by different mutations in the same gene. The two conditions differ in their severity, age of onset, and rate of progression. In boys with Duchenne muscular dystrophy, muscle weakness tends to appear in early childhood and worsen rapidly. Affected children may have delayed motor skills, such as sitting, standing, and walking. They are usually wheelchair-dependent by adolescence. The signs and symptoms of Becker muscular dystrophy are usually milder and more varied. In most cases, muscle weakness becomes apparent later in childhood or in adolescence and worsens at a much slower rate.
Both the Duchenne and Becker forms of muscular dystrophy are associated with a heart condition called cardiomyopathy. This form of heart disease weakens the cardiac muscle, preventing the heart from pumping blood efficiently. In both Duchenne and Becker muscular dystrophy, cardiomyopathy typically begins in adolescence. Later, the heart muscle becomes enlarged, and the heart problems develop into a condition known as dilated cardiomyopathy. Signs and symptoms of dilated cardiomyopathy can include an irregular heartbeat (arrhythmia), shortness of breath, extreme tiredness (fatigue), and swelling of the legs and feet. These heart problems worsen rapidly and become life-threatening in many cases. Males with Duchenne muscular dystrophy typically live into their twenties, while males with Becker muscular dystrophy can survive into their forties or beyond.
How common is Duchenne and Becker muscular dystrophy?
Duchenne and Becker muscular dystrophies together affect 1 in 3,500 to 5,000 newborn males worldwide. Between 400 and 600 boys in the United States are born with these conditions each year.
How do people inherit Duchenne and Becker muscular dystrophy?
This condition is inherited in an X-linked recessive pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
In about two-thirds of cases, an affected male inherits the mutation from his mother, who carries one altered copy of the DMD gene. The other one-third of cases probably result from new mutations in the gene in affected males and are not inherited.
In X-linked recessive inheritance, a female with one mutated copy of the gene in each cell is called a carrier. She can pass on the altered gene but usually does not experience signs and symptoms of the disorder. Occasionally, however, females who carry a DMD gene mutation may have muscle weakness and cramping. These symptoms are typically milder than the severe muscle weakness and atrophy seen in affected males. Females who carry a DMD gene mutation also have an increased risk of developing heart abnormalities including cardiomyopathy.
Team Strathman 