What is Duchenne Muscular Dystrophy (DMD)?
It is a muscle wasting condition that is caused due to lack of protein called dystrophin. It is a serious condition where there is progressive muscle weakness. Due to lack of the protein dystrophin (needed to build and repair muscles), the muscle fibers gradually break down and are replaced by fibrous or fatty tissue leading to muscle weakness and disability.
It mainly affects boys.
Causes of DMD
It is a genetic condition – either inherited (X linked recessive condition) or new mutation, in genetic code (DNA). IT affects the gene called dystrophin, which is located on X chromosome (female sex chromosome).
Generally if the females have the mutated chromosome, she becomes the carrier and not affected (females have XX or 2X genes, one is mutated and the other helps produce the dystrophin protein). However, some can display a small degree of muscle weakness and are called “manifesting carriers”.
If the sons inherit the mutated gene then they are affected (they have 1X chromosome from mother and other is Y chromosome from father).
Sons of carrier mothers have 50:50 chances of being affected and daughters have 50:50 chances of being a carrier.
How is DMD Diagnosed?
Most children are diagnosed before the age of 5years. They generally start displaying symptoms of muscular dysfunction between ages of 1-3. Boys might start walking later than their peers, fall often or find it difficult to jump, run or get up from the floor. They might have enlarged calf muscles. Some boys may have delayed speech.
DMD is confirmed by genetic testing on a blood sample. Other blood tests to suggest DMD are raised CK (creatine kinase, a protein that leaks from damaged muscle fibers), and raised liver enzymes.
Genetic testing is crucial, as it enable families to make decision on prenatal diagnosis in future pregnancies and other members in the family who might be at high risk of carrying the mutation gene.
Is there a Treatment or Cure?
There is no cure for the condition yet but there is promising research ongoing.
Management is a multi disciplinary approach, with inputs from physiotherapist, occupational therapist, respiratory and cardiac specialists. Regular check ups with the specialists are vital to ensure appropriate and timely treatment; also to foresee and prevent problems.
Steroids (prednisone or deflazacort) are often prescribed to slow down the decline of muscle strength; and to prevent or post pone the development of complications.
Intense research is ongoing, in trying to find treatments for DMD. Some are available in Europe and some are having clinical trials.
What is the prognosis?
DMD is a progressive disease; changes are generally subtle than sudden or drastic. It starts with muscle weakness where the boys show difficulty with running, jumping, climbing stairs or getting up from the floor, as the weakness progresses they then find walking difficult. Generally they would need a wheelchair by age of around 11years, initially for long distances then may need it full-time. It also affects their posture and may lead to complications. By late teens they might face life-threatening complications due to involvement of muscles of heart and lungs.
Some may have learning or behavioral difficulties due to the impact it has on the brain, but this is not progressive. Hence timely diagnosis and support can help them develop skill and reach their full learning potential. Family support is essential and may need specialists’ inputs to help with learning and behavioral issues.
With usage of steroids, the natural course of the disease has significantly changed. Few of those born with DMD, currently live to see their 30th birthday; with medical advances, life expectancy is improving.
The right healthcare specialists and equipment, including access to respiratory, cardiac experts and regular physiotherapy; can make a significant difference to both quality and length of life expectancy of people with DMD.
While it can be severely disabling, many have led full and active lives.